Quiz
HUBS Cardiovascular
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Questions in this quiz (71)
1The circulatory system
- Atransports blood around the body, delivering oxygen and nutrients to organs and removing wastes.
- Btransports blood around the body, delivering nutrients and carbon dioxide to organs and removing wastes.
- Ctransports blood around the body, delivering carbon dioxide and oxygen to organs and removing wastes
- Dtransports blood around the body, delivering oxygen, carbon dioxide and nutrients to organs and removing wastes.
2The [blank_start]pulmonary[blank_end] circuit and [blank_start]systemic[blank_end] circuit act in series. The [blank_start]systemic[blank_end] circuit is made up of [blank_start]many[blank_end] circulatory systems in [blank_start]parallel[blank_end].
- Apulmonary
- Brespiratory
- Clung
- Dcentral
- Esystemic
- Fbody
- Goxygen
- Hperipheral
- Isystemic
- Jpulmonary
- Kcentral
- Lperipheral
- Mmany
- Ntwo
- Othree
- Pten
- Qparallel
- Rseries
3Haemodynamics is how how blood flows in a single vessel. There are two factors that determine how blood flows in a single vessel: [blank_start]pressure[blank_end] and [blank_start]resistance[blank_end].
[blank_start]Flow[blank_end] = [blank_start]Pressure Difference[blank_end] / [blank_start]Resistance[blank_end]
[blank_start]Bigger[blank_end] vessels = less resistance
[blank_start]Smaller[blank_end] vessels = more resistance
[blank_start]The heart[blank_end] generates pressure so it is [blank_start]highest[blank_end] leaving the heart. When blood comes back into heart, pressure is [blank_start]very low ~0[blank_end]- Apressure
- Bforce
- Cheart rate
- Dgravity
- Eresistance
- Fspeed
- Gdistance
- Henergy
- IFlow
- JPressure Difference
- KResistance
- LPressure Difference
- MFlow
- NResistance
- OResistance
- PFlow
- QPressure Difference
- RBigger
- SSmaller
- TLonger
- UShorter
- VSmaller
- WBigger
- XLonger
- YShorter
- ZThe heart
- AAGravity
- ABThe arteries
- ACThe veins
- ADhighest
- AElowest
- AFvariable
- AGvery low ~0
- AHvery high
- AIabout 50%
4The supply side
[blank_start]Arteries[blank_end] are positioned to prevent injury to them as they are [blank_start]pressurised[blank_end] with [blank_start]high velocity blood[blank_end] so they are situated [blank_start]deep in trunk[blank_end] and in [blank_start]flexor[blank_end] aspects of limbs. Important structures often receive supply from [blank_start]two sources (two separate arteries)[blank_end]. Arteries change their name at each [blank_start]major branch[blank_end].- AArteries
- BVeins
- CCapillaries
- Dpressurised
- Edelicate
- Fhard to repair
- Ghigh velocity blood
- Hlow velocity blood
- Ihigh volumes of blood
- Jlow volumes of blood
- Kdeep in trunk
- Lsuperficially
- Mflexor
- Nextensor
- Otwo sources (two separate arteries)
- Ptwo sources (artery and vein)
- Qmany sources
- Ra single major artery
- Smajor branch
- Tjoint in the body
- Udestination
5Drainage:
Three pathways for drainage
1. [blank_start]deep veins[blank_end] (located by major supply arteries)
2. [blank_start]superficial veins[blank_end]
3. [blank_start]lymphatics[blank_end] (network of little channels to take fluid that has left the blood vascular space)
Cross-sectional area of veins is at least [blank_start]twice[blank_end] that of arteries to shift the same volume of blood/second.- Adeep veins
- Bsuperficial veins
- Clymphatics
- Dtwice
6The Blood Vascular System is [blank_start]a closed supply and drainage system[blank_end] i.e. it is a [blank_start]continuous loop[blank_end].
The Lymphatic Vascular System is [blank_start]an open-entry drainage system[blank_end] i.e. it is a [blank_start]one-way system[blank_end].- Aa closed supply and drainage system
- Ban open-entry drainage system
- Can open-ended supply system
- Dan open exchange system
- Econtinuous loop
- Fone-way system
- Gtwo-way system
- Han open-entry drainage system
- Ia closed supply and drainage system
- Jan open-ended supply system
- Kan open exchange system
- Lone-way system
- Mcontinuous loop
- Ntwo-way system
7The Right Atrium receives blood from the [blank_start]superior vena cava[blank_end] (chest and up), [blank_start]inferior vena cava[blank_end] (biggest, everything below diaphragm) and [blank_start]coronary sinus[blank_end] (heart).
The Left atrium receives the blood from the [blank_start]four pulmonary veins[blank_end].- Asuperior vena cava
- Binferior vena cava
- Ccoronary sinus
- Dfour pulmonary veins
8The human heart is a [blank_start]four-chambered[blank_end] [blank_start]muscular[blank_end] organ, shaped and sized roughly like [blank_start]a person’s closed fist[blank_end]. It lies in the [blank_start]middle region of the thorax[blank_end], behind the [blank_start]sternum[blank_end] between the [blank_start]second through sixth ribs[blank_end]. Approximately [blank_start]two thirds[blank_end] of the heart’s mass is to the left of the midline, and [blank_start]one third[blank_end] is to the right.
The [blank_start]lower[blank_end] border of the heart, which forms a blunt point known as the [blank_start]apex[blank_end], lies on the [blank_start]diaphragm[blank_end], pointing toward the [blank_start]left[blank_end].- Afour-chambered
- Btwo-chambered
- Csingle-chambered
- Dmuscular
- Efatty
- Fcartilaginous
- Ga person’s closed fist
- Ha matchbox
- Ia can of rice pudding
- Ja running shoe
- Kmiddle region of the thorax
- Lleft region of the thorax
- Mlower region of the abdomen
- Nupper region of the abdomen
- Osternum
- Plungs
- Qstomach
- Rspine
- Ssecond through sixth ribs
- Tfirst through fifth ribs
- Uthird through seventh ribs
- Vfourth through eighth ribs
- Wtwo thirds
- Xone third
- Yone half
- Z90%
- AAone third
- ABtwo thirds
- ACone half
- AD10%
- AElower
- AFupper
- AGapex
- AHbase
- AIdiaphragm
- AJlungs
- AKlower ribs
- ALheart sac
- AMleft
- ANright
9STRUCTURE OF THE HEART COVERINGS
The heart has its own special covering, a [blank_start]loose-fitting inextensible[blank_end] sac called the [blank_start]pericardium[blank_end]. The [blank_start]pericardium[blank_end] consists of two parts: [blank_start]a fibrous portion and a serous portion[blank_end]. The sac itself is made of [blank_start]tough white fibrous tissue[blank_end] but is lined with [blank_start]smooth, moist serous membrane[blank_end]—the [blank_start]parietal[blank_end] layer of the [blank_start]serous pericardium[blank_end]. The same kind of membrane covers the entire outer surface of the heart. This covering layer is known as the [blank_start]visceral layer of the serous pericardium[blank_end] or the [blank_start]epicardium[blank_end]. The [blank_start]fibrous sac[blank_end] attaches to the large blood vessels emerging from the top of the heart [blank_start]but not[blank_end] to the heart itself. Therefore it fits [blank_start]loosely[blank_end] around the heart, with [blank_start]a slight[blank_end] space between the visceral layer adhering to [blank_start]the heart[blank_end] and the parietal layer adhering to [blank_start]the inside of the fibrous sac[blank_end]. This space is called the [blank_start]pericardial space[blank_end]. It contains 10 to 15 ml of [blank_start]pericardial[blank_end] fluid, a lubricating fluid secreted by the [blank_start]serous membrane[blank_end].
[blank_start]Fibrous pericardium[blank_end]—tough, loose-fitting, and inelastic sac around the heart
[blank_start]Serous pericardium[blank_end]—consisting of two layers
1. [blank_start]Parietal layer[blank_end]—lining inside the fibrous pericardium
2. [blank_start]Visceral layer[blank_end] ([blank_start]epicardium[blank_end])—adhering to the outside of the heart; between visceral and parietal layers is a space, the pericardial space, that contains a few drops of pericardial fluid- Aloose-fitting inextensible
- Btight-fitting inextensible
- Cloose-fitting extensible
- Dtight-fitting extensible
- Epericardium
- Fepicardium
- Gmyocardium
- Hendocardium
- Ipericardium
- Jendocardium
- Kepicardium
- Lmyocardium
- Ma fibrous portion and a serous portion
- Na parietal layer and a visceral layer
- Oa dense portion and a delicate portion
- Pan outer layer and an inner layer
- Qtough white fibrous tissue
- Rsoft white serous tissue
- Stough white serous tissue
- Tsoft white fibrous tissue
- Usmooth, moist serous membrane
- Vrough, dry fibrous membrane
- Wsmooth, moist fibrous membrane
- Xrough, dry serous membrane
- Yparietal
- Zvisceral
- AAfibrous
- ABinner
- ACserous pericardium
- ADvisceral epicardium
- AEparietal endocardium
- AFfibrous myocardium
- AGvisceral layer of the serous pericardium
- AHparietal layer of the fibrous myocardium
- AIserous layer of the parietal endocardium
- AJfibrous layer of the visceral epicardium
- AKepicardium
- ALpericardium
- AMmyocardium
- ANendocardium
- AOfibrous sac
- APserous sac
- AQbut not
- ARand
- ASloosely
- ATtightly
- AUa slight
- AVno
- AWa large
- AXa potential
- AYthe heart
- AZthe inside of the fibrous sac
- BAthe inside of the serous sac
- BBthe diaphragm
- BCthe inside of the fibrous sac
- BDthe heart
- BEthe inside of the serous sac
- BFthe diaphragm
- BGpericardial space
- BHsub-fibrous space
- BIinter-sac space
- BJserous space
- BKpericardial
- BLserous
- BMheart
- BNfibrous
- BOserous membrane
- BPfibrous membrane
- BQpericardium
- BRepicardium
- BSFibrous pericardium
- BTSerous pericardium
- BUParietal pericardium
- BVVisceral pericardium
- BWSerous pericardium
- BXFibrous pericardium
- BYParietal pericardium
- BZVisceral pericardium
- CAParietal layer
- CBVisceral layer
- CCFibrous layer
- CDSerous layer
- CEVisceral layer
- CFParietal layer
- CGFibrous layer
- CHSerous layer
- CIepicardium
- CJpericardium
- CKmyocardium
- CLendocardium
10WALL OF THE HEART
Three distinct layers of tissue make up the heart wall in both the atria and the ventricles: the [blank_start]epicardium[blank_end], [blank_start]myocardium[blank_end], and [blank_start]endocardium[blank_end].
[blank_start]Epicardium[blank_end]: The [blank_start]epicardium[blank_end] is actually the [blank_start]visceral[blank_end] layer of the [blank_start]serous pericardium[blank_end].
[blank_start]Myocardium[blank_end]: The bulk of the heart wall is the [blank_start]thick[blank_end], [blank_start]contractile[blank_end] layer of specially constructed and arranged [blank_start]cardiac muscle[blank_end] cells. [blank_start]Cardiac muscle[blank_end] tissue is composed of [blank_start]branching[blank_end] cells joined by end-to-end junctions called [blank_start]intercalated disks[blank_end]. These contain [blank_start]gap junctions[blank_end] so large areas of [blank_start]cardiac muscle[blank_end] are [blank_start]electrically[blank_end] coupled into a single functional unit called a [blank_start]syncytium[blank_end], meaning “joined cells”. The [blank_start]cardiac[blank_end] fibres form a continuous sheet of [blank_start]muscle[blank_end] that wraps entirely around the [blank_start]cavities[blank_end] within the heart so the [blank_start]myocardium[blank_end] can compress the heart [blank_start]cavities[blank_end] with great force. [blank_start]Cardiac muscles[blank_end] are [blank_start]auto rhythmic[blank_end] so they can contract on their own with a slow, steady rhythm however they cannot [blank_start]summate contractions[blank_end] to produce [blank_start]tetanus[blank_end] thus do not [blank_start]fatigue[blank_end].
[blank_start]Endocardium[blank_end]: The lining of the interior of the [blank_start]myocardial[blank_end] wall is a [blank_start]delicate[blank_end] layer known as the [blank_start]endocardium[blank_end]. It is made of a type of tissue called [blank_start]endothelial[blank_end] tissue or [blank_start]endothelium[blank_end]. [blank_start]Endothelium[blank_end] lines the heart (where it is called the [blank_start]endocardium[blank_end]) and continues on to line all of the [blank_start]blood vessels[blank_end]. It is a specialised type of [blank_start]simple squamous epithelium[blank_end]. The [blank_start]endocardium[blank_end] also covers beam-like projections of [blank_start]myocardial[blank_end] tissue which are called [blank_start]trabeculae carneae[blank_end] and help to add force to the [blank_start]inward contraction[blank_end] of the heart wall. Inward [blank_start]folds[blank_end] or pockets formed by the [blank_start]endocardium[blank_end] and supporting [blank_start]connective[blank_end] tissue make up the flaps or [blank_start]cusps[blank_end] of the major [blank_start]heart valves[blank_end]. These [blank_start]valves[blank_end] ensure the [blank_start]one[blank_end]-way flow of blood through the chambers of the heart, thus enabling the heart to act as a [blank_start]pump[blank_end].- Aepicardium
- Bmyocardium
- Cendocardium
- DEpicardium
- Eepicardium
- Fvisceral
- Gserous pericardium
- HMyocardium
- Ithick
- Jcontractile
- Kcardiac muscle
- LCardiac muscle
- Mbranching
- Nintercalated disks
- Ogap junctions
- Pcardiac muscle
- Qelectrically
- Rsyncytium
- Scardiac
- Tmuscle
- Ucavities
- Vmyocardium
- Wcavities
- XCardiac muscles
- Yauto rhythmic
- Zsummate contractions
- AAtetanus
- ABfatigue
- ACEndocardium
- ADmyocardial
- AEdelicate
- AFendocardium
- AGendothelial
- AHendothelium
- AIEndothelium
- AJendocardium
- AKblood vessels
- ALsimple squamous epithelium
- AMendocardium
- ANmyocardial
- AOtrabeculae carneae
- APinward contraction
- AQfolds
- ARendocardium
- ASconnective
- ATcusps
- AUheart valves
- AVvalves
- AWone
- AXpump
11CHAMBERS OF THE HEART
The interior of the heart is divided into four [blank_start]cavities[blank_end] or chambers. The two upper chambers are called [blank_start]atria[blank_end] (singular, [blank_start]atrium[blank_end]), and the two lower chambers are called [blank_start]ventricles[blank_end]. The left chambers are separated from the right chambers by an extension of the heart wall called the [blank_start]septum[blank_end].
[blank_start]Atria[blank_end]: The two superior chambers of the heart are separated into left and right chambers by the [blank_start]inter-atrial septum[blank_end]. [blank_start]Atria[blank_end] are often called the “[blank_start]receiving[blank_end] chambers” because they [blank_start]receive[blank_end] blood from vessels called [blank_start]veins[blank_end]. The [blank_start]atria[blank_end] alternately relax and contract to [blank_start]receive[blank_end] blood, then push it into the [blank_start]lower chambers[blank_end]. The [blank_start]atria[blank_end] [blank_start]do not need[blank_end] to generate great pressure to move blood such a [blank_start]small[blank_end] distance so the [blank_start]myocardial[blank_end] wall of each [blank_start]atrium[blank_end] is [blank_start]not very[blank_end] thick. The term [blank_start]auricle[blank_end] (meaning “little ear”) refers to the ear-like flap protruding from each [blank_start]atrium[blank_end].
[blank_start]Ventricles[blank_end]: The two inferior chambers of the heart are separated into left and right chambers by the [blank_start]inter-ventricular septum[blank_end]. The [blank_start]ventricles[blank_end] receive blood from the [blank_start]atria[blank_end] and pump blood [blank_start]out of[blank_end] the heart into [blank_start]arteries[blank_end] so they are considered to be the primary “[blank_start]pumping[blank_end] chambers” of the heart. The [blank_start]myocardium[blank_end] of the [blank_start]left ventricle[blank_end] is thicker than the [blank_start]right ventricle[blank_end] because the [blank_start]left ventricle[blank_end] pushes blood round the whole body, whereas the [blank_start]right ventricle[blank_end] pushes blood only to the [blank_start]lungs[blank_end] and the [blank_start]myocardium[blank_end] of each [blank_start]ventricle[blank_end] is thicker than the [blank_start]myocardium[blank_end] of either [blank_start]atrium[blank_end].- Acavities
- Batria
- Catrium
- Dventricles
- Eseptum
- FAtria
- Ginter-atrial septum
- HAtria
- Ireceiving
- Jreceive
- Kveins
- Latria
- Mreceive
- Nventricles
- Oatria
- Pdo not need
- Qsmall
- Rmyocardial
- Satrium
- Tnot very
- Uauricle
- Vatrium
- WVentricles
- Xinter-ventricular septum
- Yventricles
- Zatria
- AAout of
- ABarteries
- ACpumping
- ADmyocardium
- AEleft ventricle
- AFright ventricle
- AGleft ventricle
- AHright ventricle
- AIlungs
- AJmyocardium
- AKventricle
- ALmyocardium
- AMatrium
12FUNCTION OF THE HEART COVERINGS
The [blank_start]fibrous pericardial[blank_end] sac with its smooth, well-lubricated lining provides protection against [blank_start]friction[blank_end]. The heart moves [blank_start]easily[blank_end] in this [blank_start]loose[blank_end]-fitting jacket with no danger of irritation from [blank_start]friction[blank_end] between the two surfaces, as long as the [blank_start]serous pericardium[blank_end] remains normal and continues to produce lubricating [blank_start]serous[blank_end] fluid.- Afibrous pericardial
- Bfriction
- Ceasily
- Dloose
- Efriction
- Fserous pericardium
- Gserous
13VALVES OF THE HEART
The heart valves permit the flow of blood in [blank_start]one direction[blank_end] only, allowing the heart to act as a [blank_start]pump[blank_end] that forces the [blank_start]continuous[blank_end] flow of blood in [blank_start]one direction[blank_end].
[blank_start]Atrioventricular[blank_end] Valves: The [blank_start]atrioventricular[blank_end] valves guard the openings between the atria and the ventricles. They have pointed leaflets or flaps called [blank_start]cusps[blank_end] and are therefore also called [blank_start]cuspid[blank_end] valves. The valve which regulates flow through the right [blank_start]atrioventricular[blank_end] opening consists of [blank_start]three[blank_end] flaps ([blank_start]cusps[blank_end]) of [blank_start]endocardium[blank_end] so it is called the [blank_start]tricuspid[blank_end] valve. The free edge of each flap is anchored to the [blank_start]papillary[blank_end] muscles of the right ventricle by several tendinous cords called [blank_start]chordae tendineae[blank_end]. The valve that guards the left [blank_start]atrioventricular[blank_end] opening is similar in structure to the right except that it has [blank_start]only two[blank_end] flaps so is sometimes known as the [blank_start]bicuspid[blank_end] valve although it is more commonly called the [blank_start]mitral[blank_end] valve. When ventricles are [blank_start]relaxed[blank_end], blood flows through the AV valves from the atria. Ventricular [blank_start]contraction[blank_end] forces the blood in the ventricles hard against the valve flaps, [blank_start]closing[blank_end] them. The [blank_start]papillary[blank_end] muscles [blank_start]contract[blank_end] along with the rest of the ventricular [blank_start]myocardium[blank_end] which holds the edges of the [blank_start]cusps[blank_end] and prevents them from bending [blank_start]backwards[blank_end] and allowing blood to flow back into the atria. Keeping the AV valves closed during ventricular [blank_start]contraction[blank_end] ensures the movement of the blood upward into the pulmonary trunk and aorta as the ventricles [blank_start]contract[blank_end].
[blank_start]Semilunar[blank_end] Valves: The [blank_start]semilunar (SL)[blank_end] valves are located where the trunk of the [blank_start]pulmonary artery[blank_end] joins the right ventricle ([blank_start]pulmonary[blank_end] valve) and where the [blank_start]aorta[blank_end] joins the left ventricle ([blank_start]aortic[blank_end] valve). They consist of pocket-like flaps ([blank_start]leaflets[blank_end]) extending inward. [blank_start]Semilunar[blank_end] refers to the crescent shape of the valve cusps visible in a frontal section of the heart. When the [blank_start]pulmonary and aortic[blank_end] valves are [blank_start]closed[blank_end], blood fills the spaces between the leaflets and the vessel wall like a tiny, filled bucket. Inflowing blood smoothes the leaflets against the blood vessel walls, collapsing the buckets and [blank_start]opening[blank_end] the valves. Closure of the [blank_start]semilunar[blank_end] valves, as of the [blank_start]atrioventricular[blank_end] valves, prevents [blank_start]backflow[blank_end] and ensures [blank_start]forward[blank_end] flow of blood.- Aone direction
- Bpump
- Ccontinuous
- Done direction
- EAtrioventricular
- Fatrioventricular
- Gcusps
- Hcuspid
- Iatrioventricular
- Jthree
- Kcusps
- Lendocardium
- Mtricuspid
- Npapillary
- Ochordae tendineae
- Patrioventricular
- Qtwo
- Rbicuspid
- Smitral
- Trelaxed
- Ucontraction
- Vclosing
- Wpapillary
- Xcontract
- Ymyocardium
- Zcusps
- AAbackwards
- ABcontraction
- ACcontract
- ADSemilunar
- AEsemilunar
- AFpulmonary
- AGpulmonary artery
- AHaorta
- AIaortic
- AJleaflets
- AKSemilunar
- ALsemilunar
- AMopening
- ANclosed
- AOsemilunar
- APatrioventricular
- AQbackflow
- ARforward
14Flow of Blood Through the Heart
Deoxygenated blood flows into the heart from the [blank_start]vena cava[blank_end] into the [blank_start]right atrium[blank_end] then through the [blank_start]right atrioventricular (tricuspid)[blank_end] valve into the [blank_start]right ventricle[blank_end]. From there, blood flows through the [blank_start]pulmonary semilunar[blank_end] valve into the [blank_start]pulmonary trunk[blank_end] which branches to form the left and right [blank_start]pulmonary arteries[blank_end]. These conduct blood to the [blank_start]gas exchange tissues of the lung[blank_end] then the oxygenated blood flows through [blank_start]pulmonary veins[blank_end] back to the [blank_start]heart[blank_end]. Oxygenated blood flows into the heart into the [blank_start]left atrium[blank_end] then through the [blank_start]left atrioventricular (mitral)[blank_end] valve into the [blank_start]left ventricle[blank_end]. From there, blood flows through the [blank_start]aortic semilunar[blank_end] valve into the [blank_start]aorta[blank_end] which branches to supply all the tissues of the body except the [blank_start]gas-exchange tissues of the lungs[blank_end]. Blood leaving the head, neck, and upper extremities empties into the [blank_start]superior vena cava[blank_end]. Blood leaving the lower body empties into the [blank_start]inferior vena cava[blank_end]. Both large vessels conduct blood into the [blank_start]right atrium[blank_end], bringing us back to the point where we began.- Avena cava
- Baorta
- Catrial vein
- Dpulmonary vein
- Eright atrium
- Fleft atrium
- Gright ventricle
- Hleft ventricle
- Iright atrioventricular (tricuspid)
- Jleft atrioventricular (tricuspid)
- Kright atrioventricular (mitral)
- Lleft atrioventricular (mitral)
- Mright ventricle
- Nleft ventricle
- Oright atrium
- Pleft atrium
- Qpulmonary semilunar
- Raortic semilunar
- Spulmonary atrioventricular
- Taortic atrioventricular
- Upulmonary trunk
- Vaortic trunk
- Wvena cava trunk
- Xcoronary sinus trunk
- Ypulmonary arteries
- Zaortic branches
- AAvena cava
- ABcoronary arteries
- ACgas exchange tissues of the lung
- ADcardiac muscles
- AEleft and right sides of the body
- AFbrain
- AGpulmonary veins
- AHthe vena cava
- AIcardiac veins
- AJthe aorta
- AKheart
- ALlungs
- AMbrain
- ANbody
- AOleft atrium
- APright atrium
- AQleft ventricle
- ARright ventricle
- ASleft atrioventricular (mitral)
- ATright atrioventricular (mitral)
- AUright atrioventricular (tricuspid)
- AVleft atrioventricular (tricuspid)
- AWleft ventricle
- AXright ventricle
- AYleft atrium
- AZright atrium
- BAaortic semilunar
- BBpulmonary semilunar
- BCpulmonary atrioventricular
- BDaortic atrioventricular
- BEaorta
- BFpulmonary artery
- BGvena cava
- BHperipheral artery
- BIgas-exchange tissues of the lungs
- BJheart
- BKbrain
- BLcourage
- BMsuperior vena cava
- BNsuperior aorta
- BOdescending vena cava
- BPdescending aorta
- BQinferior vena cava
- BRascending vena cava
- BSinferior aorta
- BTascending aorta
- BUright atrium
- BVleft atrium
- BWright ventricle
- BXleft ventricle
15The Purkinje fibres are specialised [blank_start]conducting[blank_end] fibres composed of [blank_start]electrically excitable[blank_end] cells that are [blank_start]larger than[blank_end] cardiomyocytes with fewer [blank_start]myofibrils[blank_end] and a large number of [blank_start]mitochondria (and glycogen)[blank_end] and lots of [blank_start]gap junctions[blank_end] to conduct cardiac [blank_start]action potentials[blank_end] more quickly and efficiently than [blank_start]any other cells[blank_end] in the heart. There are some [blank_start]peripheral myofibrils[blank_end], a central [blank_start]nucleus[blank_end] and some [blank_start]desmosomes[blank_end]. They make up approximately [blank_start]1%[blank_end] of cardiac cells. Purkinje fibres allow the heart's conduction system to create [blank_start]synchronized[blank_end] contractions of its ventricles so they are essential for maintaining a [blank_start]consistent[blank_end] heart rhythm.
- Aconducting
- Bcontracting
- Crelaxing
- Dpumping
- Eelectrically excitable
- Finsulating
- Gcardiac muscle
- Hsmooth muscle
- Ilarger than
- Jsmaller than
- Kthe same size as
- Lmyofibrils (actin and myosin)
- Mgap junctions
- Nmitochondria (and glycogen)
- Onuclei
- Pmitochondria (and glycogen)
- Qmyofibrils (actin and myosin)
- Rnuclei
- Sstriations
- Tgap junctions
- Udesmosomes
- Vadhesion belts
- Wtight junctions
- Xaction potentials
- Ymessages
- Zsignalling
- AAactive potencies
- ABany other cells
- ACmost other cells
- ADsome other cells
- AEinsulating cells
- AFperipheral myofibrils
- AGgap junctions
- AHmitochondria
- AInodes
- AJnucleus
- AKaxon hillock
- ALnode
- AMbundle
- ANdesmosomes
- AOgap junctions
- APtight junctions
- AQadhesion belts
- AR1%
- AS1/3
- AT50%
- AU10%
- AVsynchronized
- AWlarge
- AXnumerous
- AYfast
- AZconsistent
- BAfast
- BBstrong
- BCvariable
16Histological Structure of the Blood Vessels
Blood vessels have a three layered wall (from inside to outside):
1. [blank_start]Tunica Intima[blank_end]
2. [blank_start]Tunica Media[blank_end]
3. [blank_start]Tunica Adventitia[blank_end] ([blank_start]Externa[blank_end])
The most internal wall, [blank_start]Tunica Intima[blank_end], has three layers:
1. [blank_start]Endothelium[blank_end] - A [blank_start]simple squamous epithelium[blank_end] which lines the [blank_start]lumen[blank_end] of all vessels.
2. [blank_start]Sub-endothelium[blank_end] - A [blank_start]sparse[blank_end] pad of [blank_start]loose FCT[blank_end]. cushioning the [blank_start]endothelium[blank_end].
3, [blank_start]Internal Elastic Lamina (IEL)[blank_end]- a [blank_start]condensed sheet of elastic tissue[blank_end]. The [blank_start]IEL[blank_end] is well developed in [blank_start]arteries[blank_end] and less developed in [blank_start]veins[blank_end].
The middle layer is [blank_start]Tunica Media[blank_end]
It is made from [blank_start]Smooth muscle cells[blank_end] and has a [blank_start]variable[blank_end] content of [blank_start]connective tissue fibres[blank_end] (mainly [blank_start]elastin and collagen[blank_end]). The thickness of the media is proportional to [blank_start]both vessel diameter and blood pressure[blank_end]. Thicker media = [blank_start]higher[blank_end] pressure therefore [blank_start]arteries[blank_end] have a thicker [blank_start]tunica media[blank_end] than [blank_start]veins[blank_end].
The outer layer is [blank_start]Tunica Adventitia (Externa)[blank_end]It is made of [blank_start]loose FCT[blank_end] with a high content of [blank_start]collagen[blank_end] and variable amount of [blank_start]elastin[blank_end]. In [blank_start]larger[blank_end] vessels, the adventitia contains the [blank_start]vasa vasorum[blank_end]. [blank_start]Lymphatics and autonomic nerves[blank_end] are also found in this region.- ATunica Intima
- BTunica Interna
- CTunica Inside
- DTunica Deep
- ETunica Media
- FTunica Middle
- GTunica Medium
- HTunica Median
- ITunica Adventitia
- JTunica Adventurous
- KTunica Advantageous
- LTunica Advil
- MExterna
- NOuter
- OOutside
- PSuperficial
- QTunica Intima
- RTunica Interna
- STunica Inside
- TTunica Deep
- UEndothelium
- VEndocardium
- WEndomysium
- XEndovesslium
- Ysimple squamous epithelium
- Zsimple cuboidal muscle cells
- AAstratified cuboidal epithelium
- ABstratified squamous muscle cells
- AClumen
- ADinside
- AEoutside
- AFstroma
- AGSub-endothelium
- AHInter-tunica
- AIHypo-laminal
- AJHyper-epithelium
- AKloose fibrous connective tissue
- ALdense fibrous connective tissue
- AMloose elastic connective tissue
- ANtight elastic connective tissue
- AOendothelium
- APendocardium
- AQendomysium
- ARendovesslium
- ASInternal Elastic Lamina (IEL)
- ATExternal Fibrous Lamina (EFL)
- AUInternal Fibrous Lamina (IFL)
- AVExternal Elastic Lamina (EEL)
- AWsparse
- AXcondensed
- AYcondensed sheet of elastic tissue
- AZsparse sheet of elastic tissue
- BAcondensed sheet of fibrous tissue
- BBsparse sheet of fibrous tissue
- BCIEL
- BDIFL
- BEEFL
- BFEEL
- BGarteries
- BHveins
- BIveins
- BJarteries
- BKTunica Media
- BLTunica Middle
- BMTunica Medium
- BNTunica Median
- BOSmooth muscle cells
- BPElastic connective tissue
- BQCardiac muscle cells
- BRFibrous connective tissue
- BSvariable
- BThigh
- BUlow
- BVconnective tissue fibres
- BWmuscle cells
- BXnervous cells
- BYepithelial tissue fibres
- BZelastin and collagen
- CAsmooth and muscle
- CBneuron and myelin
- CCsimple and squamous
- CDboth vessel diameter and blood pressure
- CEboth vessel diameter and length
- CFboth vessel length and blood pressure
- CGlength, diameter and blood pressure
- CHhigher
- CIlower
- CJarteries
- CKveins
- CLveins
- CMarteries
- CNtunica media
- COtunica medium
- CPtunica median
- CQtunica middle
- CRTunica Adventitia (Externa)
- CSTunica Advantageous (Outside)
- CTTunica Advil (Outer)
- CUTunica Adventurous (Superficial)
- CVloose FCT
- CWdense FCT
- CXloose ECT
- CYdense ECT
- CZcollagen
- DAelastin
- DBkeratin
- DCelastin
- DDcollagen
- DEkeratin
- DFlarger
- DGsmaller
- DHcardiac
- DIimportant
- DJvasa vasorum
- DKwaka wakorum
- DLyada yadorum
- DMtata tatorum
- DNLymphatics and autonomic nerves
- DOStorage cells and small blood vessels
- DPLymph nodes and somatic ganglia
- DQTransport cells and small blood vessels
17Arteries
An artery is a vessel that carries blood [blank_start]away from[blank_end] the heart. There are several types of arteries in the cardiovascular system:
- [blank_start]Elastic[blank_end] arteries, also called [blank_start]conducting[blank_end] arteries, are the [blank_start]largest[blank_end] in the body and include the [blank_start]aorta[blank_end] and some of its major branches. As the name implies, [blank_start]elastic[blank_end] arteries can [blank_start]stretch[blank_end] without causing injury to accommodate the [blank_start]surge of blood[blank_end] that is forced into them when the [blank_start]ventricles contract[blank_end] and then [blank_start]recoil[blank_end] when the [blank_start]ventricles relax[blank_end].
- [blank_start]Muscular[blank_end] arteries, also called [blank_start]distributing[blank_end] arteries, carry blood [blank_start]farther[blank_end] away from the heart to specific organs and areas of the body. They are [blank_start]smaller[blank_end] in diameter than [blank_start]elastic[blank_end] arteries. However, the [blank_start]muscular[blank_end] layer in the wall of these vessels is proportionately [blank_start]thicker[blank_end]. Because of the [blank_start]thick muscle[blank_end] layer, [blank_start]muscular[blank_end] arteries have a [blank_start]thicker[blank_end] vessel wall than similar-sized veins.
- [blank_start]Arterioles[blank_end], also called [blank_start]resistance[blank_end] vessels, are the [blank_start]smallest[blank_end] arteries. [blank_start]Arterioles[blank_end] are not named individually, but as a group. They are critically important in [blank_start]regulating[blank_end] blood flow throughout the body. They function in this way by [blank_start]variable contraction[blank_end] of [blank_start]smooth[blank_end] muscle in their walls, which in turn [blank_start]increases resistance[blank_end] to blood flow and helps regulate [blank_start]blood pressure[blank_end] as well as determine the [blank_start]quantity of blood[blank_end] that enters a particular organ.
- [blank_start]Metarteriole[blank_end] is the term used to describe the short connecting vessel that connects a true [blank_start]arteriole[blank_end] with the [blank_start]proximal[blank_end] end of between 20 and 100 [blank_start]capillaries[blank_end] and then extends through the capillary bed. The [blank_start]proximal[blank_end] ends of [blank_start]metarterioles[blank_end] have “[blank_start]regulatory valves[blank_end]” called [blank_start]precapillary sphincters[blank_end] which wrap around the entrance to a capillary to [blank_start]increase or decrease[blank_end] blood flow into specific capillary networks. The [blank_start]distal[blank_end] end of a [blank_start]metarteriole[blank_end] has [blank_start]no sphincters[blank_end] and is called a [blank_start]thoroughfare channel[blank_end]. Blood can [blank_start]bypass[blank_end] intervening capillary beds and pass directly through a [blank_start]metarteriole[blank_end] into the [blank_start]thoroughfare channel[blank_end].- Aaway from
- BElastic
- Cconducting
- Dlargest
- Eaorta
- Felastic
- Gstretch
- Hsurge of blood
- Iventricles contract
- Jrecoil
- Kventricles relax
- LMuscular
- Mdistributing
- Nfarther
- Osmaller
- Pelastic
- Qmuscular
- Rthicker
- Sthick muscle
- Tmuscular
- Uthicker
- VArterioles
- Wresistance
- Xsmallest
- YArterioles
- Zregulating
- AAvariable contraction
- ABsmooth
- ACincreases resistance
- ADblood pressure
- AEquantity of blood
- AFMetarteriole
- AGarteriole
- AHproximal
- AIproximal
- AJregulatory valves
- AKmetarterioles
- ALprecapillary sphincters
- AMincrease or decrease
- ANcapillaries
- AOdistal
- APmetarteriole
- AQno sphincters
- ARthoroughfare channel
- ASbypass
- ATmetarteriole
- AUthoroughfare channel
18Capillaries
Capillaries are the microscopic vessels that carry blood from [blank_start]arterioles[blank_end] to [blank_start]venules[blank_end]. Blood flow through the arterioles, venules, and capillaries is called the [blank_start]microcirculation[blank_end]. Transfer of [blank_start]nutrients[blank_end] and other vital substances between blood and tissue cells occurs in [blank_start]capillary[blank_end] beds. Capillaries are sometimes known as the [blank_start]primary exchange[blank_end] vessels of the cardiovascular system. Capillaries are [blank_start]small[blank_end] in size but the number of them in the body is estimated to be [blank_start]in excess of 1 billion[blank_end]. They are not, however, uniformly distributed. Some body tissues, such as [blank_start]liver or cardiac muscle[blank_end], have [blank_start]high[blank_end] metabolic rates and require [blank_start]large[blank_end] numbers of capillary vessels. Other tissues, such as [blank_start]cartilage and epithelium[blank_end], are [blank_start]avascular[blank_end] and lack capillary networks altogether. Capillaries have very [blank_start]thin[blank_end] walls, a [blank_start]large[blank_end] cross-sectional area across a capillary bed and [blank_start]slow[blank_end], [blank_start]smooth[blank_end] blood flow. Capillaries are often categorised into three groups by the ease of passage of substances through their walls or by structural differences that affect their permeability:
- [blank_start]Continuous[blank_end] capillaries (5-10µm) have a continuous lining of [blank_start]endothelial[blank_end] cells with only small openings called [blank_start]intercellular clefts[blank_end] between them. This type of capillary is typically found in [blank_start]skeletal muscle[blank_end], lung, and many types of [blank_start]connective[blank_end] tissue.
- [blank_start]Fenestrated[blank_end] capillaries (5-10µm) also have [blank_start]intercellular clefts[blank_end] between their lining [blank_start]endothelial[blank_end] cells. But, in addition, they also have small “holes” or [blank_start]fenestrations[blank_end] through the [blank_start]plasma membrane[blank_end] of the [blank_start]endothelial[blank_end] cell itself. This unique structural adaptation is important to the function of a number of major organs, such as the [blank_start]kidneys and small intestines[blank_end].
- [blank_start]Sinusoid[blank_end] capillaries (20-30µm) have a much larger [blank_start]lumen[blank_end] and are more [blank_start]winding[blank_end] than other capillary types. The [blank_start]basement membrane[blank_end] that completely covers other capillaries is either [blank_start]absent or incomplete[blank_end] and the [blank_start]fenestrations[blank_end] present in the [blank_start]endothelial[blank_end] lining cells are much [blank_start]larger[blank_end] so they are very “[blank_start]leaky[blank_end]”. [blank_start]Sinusoids[blank_end] are able to permit migration of [blank_start]blood cells[blank_end] from the [blank_start]intravascular[blank_end] space into surrounding tissues in the [blank_start]bone marrow and liver[blank_end], for example.- Aarterioles
- Bvenules
- Cmicrocirculation
- Dnutrients
- Ecapillary
- Fprimary exchange
- Gsmall
- Hin excess of 1 billion
- Iliver or cardiac muscle
- Jhigh
- Klarge
- Lcartilage and epithelium
- Mavascular
- Nthin
- Olarge
- Pslow
- Qsmooth
- RContinuous
- Sendothelial
- Tintercellular clefts
- Uskeletal muscle
- Vconnective
- WFenestrated
- Xendothelial
- Yintercellular clefts
- Zfenestrations
- AAplasma membrane
- ABendothelial
- ACkidneys and small intestines
- ADSinusoid
- AElumen
- AFwinding
- AGbasement membrane
- AHabsent or incomplete
- AIfenestrations
- AJendothelial
- AKlarger
- ALleaky
- AMSinusoids
- ANblood cells
- AOintravascular
- APbone marrow and liver
19Veins
A vein is a vessel that carries blood [blank_start]toward[blank_end] the heart. After passing through the [blank_start]capillary bed[blank_end], blood flows either via a [blank_start]thoroughfare channel[blank_end] or directly into [blank_start]venules[blank_end]. These tiny veins, especially those closest to the capillary bed, have [blank_start]very narrow lumens[blank_end] and [blank_start]porous[blank_end], [blank_start]thin[blank_end] walls. Their walls consist of little more than [blank_start]endothelial[blank_end] cells, a few [blank_start]smooth muscle[blank_end] cells and an occasional [blank_start]fibroblast[blank_end]. Like capillaries, fluid can be exchanged between blood in the smallest [blank_start]venules[blank_end] and the tissue spaces and [blank_start]phagocytic white blood cells (WBCs)[blank_end] can also move out of the cardiovascular system and into areas of inflamed tissue by passing through the [blank_start]pores[blank_end] in walls of [blank_start]venules[blank_end]. As blood exits the smaller [blank_start]venules[blank_end] it enters larger venous channels, the veins, which become progressively [blank_start]larger[blank_end] as additional blood flows into them as they [blank_start]approach[blank_end] the heart. Structural changes occur in the [blank_start]walls[blank_end] of veins as they grow in size to accommodate and [blank_start]regulate[blank_end] additional blood volume and flow. Veins can accommodate [blank_start]varying[blank_end] amounts of blood with [blank_start]almost no change[blank_end] in blood pressure because of their ability to [blank_start]stretch[blank_end]. Therefore, the veins are often referred to as the [blank_start]capacitance[blank_end] vessels of the cardiovascular system. [blank_start]High capacitance[blank_end] permits veins to serve as [blank_start]reservoirs[blank_end] for blood. Veins also have [blank_start]one-way valves[blank_end], similar to the heart’s [blank_start]semilunar valves[blank_end], to keep blood moving [blank_start]toward[blank_end] the heart and prevent [blank_start]backflow[blank_end] These develop from the thin membrane ([blank_start]endothelium[blank_end]) that lines the [blank_start]lumen[blank_end]. [blank_start]Peripheral[blank_end] veins in the [blank_start]extremities[blank_end] have more [blank_start]valves[blank_end] than other veins of the body. [blank_start]Venous sinuses[blank_end] are large venous structures that have very [blank_start]thin endothelial[blank_end] walls; they also lack [blank_start]smooth muscle[blank_end] cells or other support tissues found in the outer layers of typical large veins so they cannot [blank_start]change their shape[blank_end] and thus depend on surrounding structures for support, e.g. the [blank_start]dural venous sinuses[blank_end] of the brain and the [blank_start]coronary sinus[blank_end] of the heart.- Atoward
- Bcapillary bed
- Cthoroughfare channel
- Dvenules
- Every narrow lumens
- Fporous
- Gthin
- Hendothelial
- Ismooth muscle
- Jfibroblast
- Kvenules
- LWBCs
- Mpores
- Nvenules
- Ovenules
- Plarger
- Qapproach
- Rregulate
- Swalls
- Tvarying
- Ustretch
- Vcapacitance
- WHigh capacitance
- Xreservoirs
- Yvalves
- Zsemilunar valves
- AAtoward
- ABbackflow
- ACendothelium
- ADlumen
- AEPeripheral
- AFextremities
- AGvalves
- AHVenous sinuses
- AIthin endothelial
- AJsmooth muscle
- AKchange their shape
- ALdural venous sinuses
- AMcoronary sinus
- ANminimal change
20The Lymph Vascular System is an [blank_start]open-entry[blank_end] ([blank_start]drainage[blank_end]) system.
Functions:
Drains [blank_start]excess tissue fluid[blank_end] and [blank_start]plasma proteins[blank_end] from tissues and returns them to the blood
Filters [blank_start]foreign material[blank_end] from the lymph
‘[blank_start]Screens[blank_end]’ lymph for [blank_start]foreign antigens[blank_end] and responds by releasing [blank_start]antibodies[blank_end] and activated immune cells
Absorbs [blank_start]fat[blank_end] from intestine and transports it to [blank_start]blood[blank_end]
The Lymphatic System Structure
Lymphatic vessels
Commence as large, [blank_start]blind ending capillaries[blank_end]
From [blank_start]small intestine[blank_end], a special group of lymphatic vessels called [blank_start]lacteals[blank_end] drain [blank_start]fat[blank_end]-laden lymph into a collecting vessel called the [blank_start]cisterna chyli[blank_end]
[blank_start]Larger[blank_end] (thin wall) collecting vessels have numerous [blank_start]valves[blank_end] to prevent [blank_start]back-flow[blank_end]
They resemble veins but have [blank_start]thinner[blank_end] walls, [blank_start]more[blank_end] valves, [blank_start]lymph nodes[blank_end] and no [blank_start]RBCs[blank_end].- Aopen-entry
- Bdrainage
- Cexcess tissue fluid
- Dplasma proteins
- Eforeign material
- FScreens
- Gforeign antigens
- Hantibodies
- Ifat
- Jblood
- Kblind ending capillaries
- Lsmall intestine
- Mlacteals
- Nfat
- Ocisterna chyli
- PLarger
- Qvalves
- Rbackflow
- Sthinner
- Tmore
- Ulymph nodes
- VRBCs
21The Respiratory System is a system of connected organs and structures that function to conduct [blank_start]warm[blank_end], [blank_start]moist[blank_end], [blank_start]clean[blank_end] air into close proximity with [blank_start]blood[blank_end] of the circulatory system for [blank_start]gas exchange[blank_end].
Nose and Nasal Cavity
Functions:
- Provide an airway for [blank_start]ventilation[blank_end]
- [blank_start]Filters and cleans[blank_end] the incoming air
- [blank_start]Moistens and warms[blank_end] the incoming air
- Sinuses increase [blank_start]mucosal surface area[blank_end] and also serve as [blank_start]resonating chambers[blank_end] for speech
- Sense of [blank_start]smell[blank_end], houses [blank_start]olfactory[blank_end] receptors
Structures:
[blank_start]External nose[blank_end]
[blank_start]Nasal cavity[blank_end]
[blank_start]Paranasal sinuses[blank_end]
[blank_start]Pharynx[blank_end]
[blank_start]Larynx[blank_end]- Aclean
- Bmoist
- Cwarm
- Dblood
- Egas exchange
- Fventilation
- GFilters and cleans
- HMoistens and warms
- Imucosal surface area
- Jresonating chambers
- Ksmell
- Lolfactory
- MExternal nose
- NParanasal sinuses
- ONasal cavity
- PPharynx
- QLarynx
22External nose:
- Nostrils ([blank_start]nares[blank_end]): [blank_start]anterior[blank_end] and [blank_start]external[blank_end]
- Cartilages: [blank_start]soft and flexible[blank_end] to maintain [blank_start]unobstructed[blank_end] airway
- [blank_start]Septal cartilage[blank_end]: in midline
Nasal cavity:
- Divided in midline by [blank_start]nasal septum[blank_end] - [blank_start]hyaline cartilage[blank_end] (anterior) and [blank_start]bone[blank_end] (posterior)
- Posterior [blank_start]nasal aperture[blank_end] ([blank_start]nares[blank_end]) open into the [blank_start]nasal pharynx[blank_end]
- Roof: [blank_start]ethmoid[blank_end] and [blank_start]sphenoid[blank_end] bones
- Floor: [blank_start]hard[blank_end] (anterior) and [blank_start]soft[blank_end] (posterior) [blank_start]palates[blank_end]
- [blank_start]Turbinates[blank_end]/conchae on lateral walls: three, [blank_start]mucosa[blank_end]-covered projections, the [blank_start]superior, middle and inferior[blank_end] turbinates ([blank_start]conchae[blank_end]), curved structures swirl air so that [blank_start]heavier[blank_end] particles are deflected onto the [blank_start]mucosa[blank_end], turbulence assists to [blank_start]clean[blank_end] the incoming air- Anares
- Banterior
- Cexternal
- Dsoft and flexible
- Eopen
- FSeptal cartilage
- Gnasal septum
- Hhyaline cartilage
- Ibone
- Jnasal aperture
- Knares
- Lnasal pharynx
- Methmoid
- Nsphenoid
- Ohard
- Psoft
- Qpalates
- RTurbinates
- Smucosa
- Tsuperior, middle and inferior
- Uconchae
- Vmucosa
- Wheavier
- Xclean
23Paranasal Sinuses
- A group of sinuses ([blank_start]cavities[blank_end]) surround the nose: the f[blank_start]rontal[blank_end], s[blank_start]phenoid[blank_end], e[blank_start]thmoid[blank_end] and m[blank_start]axillary[blank_end] sinuses
- Sinuses [blank_start]lighten[blank_end] the skull and help [blank_start]warm and moisten[blank_end] the incoming air
- Sinuses also allow [blank_start]sound resonance[blank_end]
- [blank_start]Mucus[blank_end] from the sinuses drain into the [blank_start]pharynx[blank_end]
- Infected [blank_start]mucus[blank_end] can block the [blank_start]drainage[blank_end], and lead to a ‘[blank_start]sinus headache[blank_end]’
Pharynx
- [blank_start]Muscular[blank_end] tube ([blank_start]funnel[blank_end]-shaped) connects the [blank_start]Nasal[blank_end] cavity and [blank_start]oral[blank_end] cavity (mouth) to the [blank_start]Larynx[blank_end] and the [blank_start]oesophagus[blank_end]
- Divided into three regions: the [blank_start]Nasopharynx[blank_end], the [blank_start]Oropharynx[blank_end] and the [blank_start]Laryngopharynx[blank_end] ([blank_start]Nasopharynx[blank_end] (above the [blank_start]soft palate[blank_end]) serves only as an [blank_start]air[blank_end] passage)- Acavities
- Brontal
- Cphenoid
- Dthmoid
- Eaxillary
- Flighten
- Gwarm and moisten
- Hsound resonance
- IMucus
- Jpharynx
- Kmucus
- Ldrainage
- Msinus headache
- NMuscular
- Ofunnel
- PNasal
- Qoral
- RLarynx
- Soesophagus
- TNasopharynx
- UOropharynx
- VLaryngopharynx
- WNasopharynx
- Xair
- Ysoft palate
24Nasopharynx
- [blank_start]Posterior[blank_end] to the [blank_start]nasal[blank_end] cavity
- Extends from the [blank_start]posterior nares[blank_end] to the [blank_start]soft palate[blank_end]
- During [blank_start]swallowing[blank_end], the [blank_start]soft palate[blank_end] and the [blank_start]uvula[blank_end] ("little grape"), swings [blank_start]posteriorly and superiorly[blank_end] (back & up), covering the nasopharynx, thus preventing [blank_start]food[blank_end] from entering the [blank_start]nasal[blank_end] cavity
- The [blank_start]auditory[blank_end] tubes drain from the [blank_start]middle ear[blank_end] into the nasopharynx.
- The [blank_start]posterior[blank_end] wall of the pharynx contains lymphoid tissue ([blank_start]pharyngeal tonsils or adenoids[blank_end]).
- Infected [blank_start]pharyngeal tonsils[blank_end] can enlarge and [blank_start]restrict[blank_end] air flow = "adenoidal" voice.
Oropharynx
- [blank_start]Posterior[blank_end] to the [blank_start]oral[blank_end] cavity and extending from the [blank_start]soft palate[blank_end] to the [blank_start]epiglottis[blank_end]
- [blank_start]Both food and air[blank_end] pass through the oropharynx
- Contains lymphoid tissue ([blank_start]palatine and lingual tonsils[blank_end])
- the [blank_start]palatine[blank_end] tonsils are commonly infected in children
- Epithelium changes in this region
- [blank_start]stratified, squamous[blank_end] epithelium;
- to protect the throat from [blank_start]friction and chemical trauma[blank_end] during food ingestion
Laryngopharynx
- The laryngopharynx is the region [blank_start]inferior[blank_end] to the [blank_start]epiglottis[blank_end]
- Extends to the level where the [blank_start]respiratory and digestive[blank_end] tracts [blank_start]diverge[blank_end]
- During [blank_start]swallowing[blank_end], [blank_start]food[blank_end] has the ‘right of way’ over [blank_start]air[blank_end] and [blank_start]breathing[blank_end] is paused- APosterior
- BAnterior
- CSuperior
- DInferior
- Enasal
- Foral
- Gaural
- Hvisual
- Iposterior nares
- Jsoft palate
- Kepiglottis
- Luvula
- Msoft palate
- Nepiglottis
- Oposterior nares
- Puvula
- Qswallowing
- Rinhaling
- Ssmelling
- Texhaling
- Usoft palate
- Vhard palate
- Wuvula
- Xepiglottis
- Ynasal fold
- Znasal valve
- AAalveolar fold
- ABadenoid
- ACposteriorly and superiorly
- ADanteriorly and inferiorly
- AEinferiorly and posteriorly
- AFsuperiorly and anteriorly
- AGfood
- AHair
- AImucus
- AJsound
- AKnasal
- ALoral
- AMaural
- ANvisual
- AOauditory
- APoptical
- AQnasal
- ARoral
- ASmiddle ear
- ATnostrils
- AUinner eye lamina
- AVmouth
- AWposterior
- AXanterior
- AYlateral
- AZmidline
- BApharyngeal tonsils or adenoids
- BBpalatine or lingual tonsils
- BCpharyngeal or lingual tonsils
- BDpalatine tonsils or adenoids
- BEpharyngeal tonsils
- BFpalatine tonsils
- BGlingual tonsils
- BHadenoids
- BIrestrict
- BJenhance
- BKprevent
- BLpermit
- BMPosterior
- BNAnterior
- BOSuperior
- BPInferior
- BQoral
- BRnasal
- BSaural
- BTvisual
- BUsoft palate
- BVposterior nares
- BWepiglottis
- BXuvula
- BYepiglottis
- BZsoft palate
- CAposterior nares
- CBuvula
- CCBoth food and air
- CDOnly food passes
- CEOnly air passes
- CFpalatine and lingual tonsils
- CGpharyngeal and palatine tonsils
- CHlingual and pharyngeal tonsils
- CIpalatine
- CJlingual
- CKpharyngeal
- CLstratified, squamous
- CMsimple, squamous
- CNstratified, cuboidal
- COsimple, cuboidal
- CPfriction and chemical trauma
- CQfriction
- CRchemical trauma
- CSinferior
- CTsuperior
- CUanterior
- CVposterior
- CWepiglottis
- CXuvula
- CYposterior nares
- CZsoft palate
- DAdiverge
- DBconverge
- DCfinish
- DDrespiratory and digestive
- DEreproductive and respiratory
- DFdigestive and reproductive
- DGswallowing
- DHbreathing
- DIfood
- DJair
- DKair
- DLfood
- DMbreathing
- DNswallowing
25Larynx
- Provides a [blank_start]patent[blank_end] airway - conducts [blank_start]air[blank_end] & protects the airway from [blank_start]collapse[blank_end]
- [blank_start]Sound/voice[blank_end] production
- Diverts [blank_start]air and food[blank_end] in proper directions ([blank_start]epiglottis[blank_end])
- [blank_start]Nine[blank_end] cartilages protect and maintain an [blank_start]open[blank_end] airway
- Extends from the region of the [blank_start]hyoid bone[blank_end] to level of the [blank_start]oesophagus[blank_end]- Apatent
- Bair
- Ccollapse
- DSound
- Eair and food
- Fepiglottis
- GNine
- Hopen
- Ihyoid bone
- Joesophagus
26Regions where air and food pass are lined with [blank_start]stratified[blank_end] (layered) [blank_start]squamous[blank_end] (flattened) epithelium. Regions where only air passes are lined with [blank_start]respiratory[blank_end] epithelium ([blank_start]mucosa[blank_end]).
Nose
- [blank_start]Vestibule[blank_end] (just above/inside the nostrils), is lined with skin that contains [blank_start]sebaceous[blank_end] and [blank_start]sweat[blank_end] glands, and [blank_start]hair follicles[blank_end] (= protection)
- The hairs ([blank_start]vibrissae[blank_end]) [blank_start]filter[blank_end] coarse particles (dust, lint, pollen, ash etc) from the inhaled air
- The movement of the [blank_start]cilia[blank_end] creates a slow moving current of [blank_start]mucus[blank_end] towards the [blank_start]pharynx[blank_end], so that the contaminated [blank_start]mucus[blank_end] is swallowed and [blank_start]hydrolysed[blank_end] (digested) by stomach acid.
- On a cold day the [blank_start]cilia[blank_end] in your nose ‘cool down’ and stop ‘[blank_start]beating[blank_end]’ - hence your nose [blank_start]dribbles[blank_end] = aka "runny nose".
The nasal cavity is lined with:
- [blank_start]Olfactory mucosa[blank_end]: openings at the roof of the nasal cavity and contains [blank_start]sensory[blank_end] (smell) receptors (CN1)
- [blank_start]Respiratory mucosa[blank_end]: [blank_start]Pseudostratified, ciliated, columnar[blank_end] epithelium (containing [blank_start]goblet[blank_end] cells)
- Underneath the [blank_start]respiratory[blank_end] epithelium lies a bed of thin- walled [blank_start]veins[blank_end], which [blank_start]warm[blank_end] the incoming air. If the inspired air temperature [blank_start]drops[blank_end], the [blank_start]vascular plexus[blank_end] responds by [blank_start]dilating[blank_end] and becoming filled with [blank_start]more[blank_end] blood, thus intensifying the heat transfer. Note: Nose bleeds originate from these thin-walled veins, which are close to the surface.- Astratified
- Bsquamous
- Crespiratory
- Dmucosa
- EVestibule
- Fsebaceous
- Gsweat
- Hhair follicles
- Ivibrissae
- Jfilter
- Kcilia
- Lmucus
- Mpharynx
- Nmucus
- Ohydrolysed
- Pcilia
- Qbeating
- Rdribbles
- SOlfactory mucosa
- Tsensory
- URespiratory mucosa
- VPseudostratified, ciliated, columnar
- Wgoblet
- Xrespiratory
- Yveins
- Zwarm
- AAdrops
- ABvascular plexus
- ACdilating
- ADmore
27Trachea to Alveoli
- [blank_start]Conducts[blank_end] air to/from site of [blank_start]gas exchange[blank_end]
- Completes the [blank_start]cleaning, warming and humidification[blank_end] of inhaled air
- [blank_start]Gas exchange[blank_end] occurs at the [blank_start]alveolus[blank_end] (pl. alveoli)
Trachea
Functions
- Maintain [blank_start]patent[blank_end] (open) airway for [blank_start]conduction[blank_end] of air
- [blank_start]Cleans, warms and humidifies[blank_end] inhaled air
- [blank_start]Cilia[blank_end] form the [blank_start]mucociliary[blank_end] escalator (‘tracheal elevator’) to remove debris to the [blank_start]pharynx[blank_end], and redirects to the [blank_start]stomach[blank_end]
Structure
- Trachea is [blank_start]anterior[blank_end] to oesophagus
- [blank_start]Rigid[blank_end] tube from [blank_start]larynx[blank_end] to [blank_start]primary bronchus[blank_end]
- Lined with [blank_start]respiratory mucosa[blank_end] (epithelium)
- [blank_start]C-shaped cartilages[blank_end] anteriorly, hose-like
- [blank_start]Trachealis muscle[blank_end] posteriorly, mainly [blank_start]smooth[blank_end]- Agas exchange
- Bcleaning, warming and humidification
- CGas exchange
- DConducts
- Ealveolus
- Fpatent
- Gconduction
- HCleans, warms and humidifies
- Imucociliary
- JCilia
- Kpharynx
- Lstomach
- Manterior
- NRigid
- Olarynx
- Pprimary bronchus
- Qrespiratory mucosa
- RC-shaped cartilage
- STrachealis muscle
- Tsmooth
28Bronchial Tree
[blank_start]Trachea[blank_end] → [blank_start]1º bronchi[blank_end] → [blank_start]2º (lobar) bronchi[blank_end] → [blank_start]3º (segmental bronchi[blank_end] (~1mm) → [blank_start]bronchioles[blank_end] (<1mm) → further branching → [blank_start]terminal bronchioles[blank_end] (<0.05mm)
[blank_start]Primary Bronchi[blank_end]: Located outside lungs, [blank_start]Left and Right 1º bronchi[blank_end][blank_start]Intrapulmonary Bronchi[blank_end]: 2º to each lobe, [blank_start]3º[blank_end] to each lobule segment, [blank_start]bronchioles[blank_end]- ATrachea
- B1º bronchi
- C2º (lobar) bronchi
- D3º (segmental) bronchi
- Ebronchioles
- Fterminal bronchioles
- GPrimary Bronchi
- HLeft and Right 1º bronchi
- IIntrapulmonary Bronchi
- J3º
- Kbronchioles
29Lung Structure
- Right and left lungs are situated within two [blank_start]pleural cavities[blank_end]
- The ‘[blank_start]apex[blank_end]’ is superior region of a lung; near the [blank_start]clavicle[blank_end]
- The ‘[blank_start]base[blank_end]’ of a lung is inferior; sits on [blank_start]diaphragm[blank_end]
- The [blank_start]costal[blank_end] surface - outer surface; against [blank_start]ribs[blank_end]
- The [blank_start]hilum[blank_end] – medial aspect; structures enter/exit
- Right lung: [blank_start]3 lobes, 2 fissures[blank_end]
- Left lung: [blank_start]2 lobes, 1 fissure[blank_end]- Apleural cavities
- Bapex
- Cclavicle
- Dbase
- Ediaphragm
- Fcostal
- Gribs
- Hhilum
- I3 lobes, 2 fissures
- J2 lobes, 1 fissure
30Blood-Gas Barrier
- Breathing rate [blank_start]12-15[blank_end] breaths/min
- [blank_start]17,000[blank_end] breaths/day
- [blank_start]6M[blank_end] breaths/yr
- The lungs have a [blank_start]LARGE[blank_end] surface area for [blank_start]gas exchange[blank_end]!
Respiratory Zone
- Alveolar [blank_start]sacs[blank_end] are like [blank_start]bunches of grapes[blank_end], containing many [blank_start]alveoli[blank_end], the site of [blank_start]gas exchange[blank_end]
- There are roughly 300 million alveoli in your lungs, accounting for most of the the [blank_start]lung volume[blank_end] and creating enormous [blank_start]surface area[blank_end]
- The walls of alveoli are very [blank_start]thin[blank_end], a single layer of [blank_start]flattened epithelial[blank_end] cells with a [blank_start]thin basement membrane[blank_end] aka basal lamina.
Alveoli
- Pocket-like, [blank_start]open[blank_end] at one side
- [blank_start]Dense capillary network[blank_end] covering the surface
- The [blank_start]alveolar and capillary[blank_end] cell walls, and their joined [blank_start]basement membranes[blank_end], form the [blank_start]respiratory membrane[blank_end] (aka the blood-gas barrier) (~1.5-2.0μm thick)
- Gas exchange occurs at this interface via [blank_start]simple diffusion[blank_end]
[blank_start]Pneumocytes[blank_end] (lung epithelial cells)
1. Type I pneuomocytes ([blank_start]squamous, epithelial[blank_end] cells)
2. Type II pneumocystis ([blank_start]cuboidal, surfactant-secreting[blank_end] cells), secrete complex [blank_start]lipoprotein[blank_end] (phosolipid) that [blank_start]reduces the surface tension[blank_end] of the alveolar fluid
Type II cells are scattered amongst the Type I cells- A12-15
- B17,000
- C6M
- DLARGE
- Egas exchange
- Fbunches of grapes
- Gsacs
- Halveoli
- Igas exchange
- Jlung volume
- Ksurface area
- Lthin
- Mflattened epithelial
- Nthin basement membrane
- Oopen
- PDense capillary network
- Qalveolar and capillary
- Rbasement membranes
- Srespiratory membrane
- Tsimple diffusion
- UPneumocytes
- Vsquamous, epithelial
- Wcuboidal, surfactant-secreting
- Xlipoprotein
- Yreduces the surface tension
31Lower Respiratory Tract Epithelium
- [blank_start]Respiratory mucosa[blank_end] ([blank_start]pseudostratified, ciliated, columnar[blank_end] epithelium, containing [blank_start]goblet[blank_end] cells) is present in most of the LRT
- Underneath the epithelium are [blank_start]mucous and serous[blank_end] glands (seromucous glands)
- Mucous cells secrete [blank_start]mucus[blank_end], and serous cells secrete a watery fluid ([blank_start]seromucous[blank_end]) containing mucus and [blank_start]enzymes[blank_end]
- Each day [blank_start]seromucous[blank_end] glands secrete >1 litre fluid containing [blank_start]anti- bacterial lysozyme[blank_end] (mucus traps dust, bacteria and other debris breathed in and the [blank_start]lysozyme[blank_end] destroys bacteria (cell walls)
- [blank_start]Respiratory[blank_end] epithelial cells secrete [blank_start]defensins[blank_end], antibacterial/anti-fungal proteins.
Respiratory Tract Structural Changes
As you descend the respiratory tract, the [blank_start]Epithelial[blank_end] cells [blank_start]decrease[blank_end] in height, [blank_start]Cartilage[blank_end] support [blank_start]decreases[blank_end] as the bronchi decrease in diameter. [blank_start]No[blank_end] cilia, or mucus- secreting cells are found in the bronchioles or alveoli therefore [blank_start]Macrophages[blank_end] remove any inhaled debris that reaches the [blank_start]bronchioles or alveoli[blank_end].- ARespiratory mucosa
- Bpseudostratified, ciliated, columnar
- Cgoblet
- Dserous and mucous
- Emucus
- Fseromucous
- Genzymes
- Hanti-bacterial lysozyme
- Ilysozyme
- Jseromucous
- KRespiratory
- Ldefensins
- MEpithelial
- Ndecrease
- OCartilage
- Pdecreases
- QNo
- RMacrophages
- Sbronchioles or alveoli
32Boyle’s Law states that pressure and volume are [blank_start]inversely proportional[blank_end] i.e. P1V1 = P2V2
therefore if volume decreases, pressure [blank_start]increases[blank_end] and if volume increases, pressure [blank_start]decreases[blank_end]. Air movement will result from a change in pressure. Pulmonary ventilation uses this gas law to provide respiratory cycles:
- [blank_start]Inspiration[blank_end] – move air into the lungs
- [blank_start]Expiration[blank_end] – moves air out of the lungs
Mechanism of pulmonary ventilation: Establish pressure gradients as air will move from region of [blank_start]HIGH[blank_end] pressure to region of [blank_start]LOW[blank_end] pressure so when alveoli pressure is [blank_start]lower[blank_end] than atmospheric = inspiration and when alveoli pressure is [blank_start]higher[blank_end] than atmospheric = expiration. Pressure gradients can be established by changing the dimensions (hence the [blank_start]volume[blank_end]) of the thorax, this is produced by the [blank_start]contraction and relaxation[blank_end] of certain muscles.- Ainversely proportional
- Bincreases
- Cdecreases
- DInspiration
- EExpiration
- FHIGH
- GLOW
- Hlower
- Ihigher
- Jvolume
- Kcontraction and relaxation
33Thoracic Joints
Anterior: [blank_start]Sternum to ribs[blank_end] - [blank_start]Hyaline cartilage[blank_end] (bars), mostly [blank_start]synovial[blank_end], one [blank_start]cartilaginous[blank_end]
Posterior: Articulations between [blank_start]thoracic vertebrae and ribs[blank_end], [blank_start]Bi-lateral[blank_end] facets (articulations) - [blank_start]costotransverse[blank_end] and [blank_start]costovertebral[blank_end], [blank_start]Synovial[blank_end] joints = movement
Thoracic Cavity
Lateral: Two [blank_start]pleural cavities[blank_end], one left and one right, for each [blank_start]lung[blank_end], [blank_start]separate[blank_end] Medial: [blank_start]Mediastinum[blank_end], contains [blank_start]heart[blank_end], pericardium, major vessels- ASternum to ribs
- BHyaline cartilage
- Csynovial
- Dcartilaginous
- Eribs and vertebrae
- FBilateral
- Gcostotransverse
- Hcostovertebral
- ISynovial
- Jseparate
- Klung
- Lpleural cavities
- MMediastinum
- Nheart
34Muscles of Respiration
1. [blank_start]Diaphragm[blank_end]
2. [blank_start]Intercostals[blank_end]
3. [blank_start]Accessory muscles[blank_end]
[blank_start]Diaphragm[blank_end] - [blank_start]Lower[blank_end] boundary of [blank_start]thoracic cavity[blank_end], i.e. the [blank_start]thoracic floor[blank_end]
- [blank_start]Skeletal[blank_end] muscle
- [blank_start]Phrenic[blank_end] nerve innervation
- [blank_start]Contracts[blank_end] during inspiration
[blank_start]Intercostals[blank_end]
Two layers of muscles located [blank_start]between the ribs[blank_end]:
1. External intercostals
- [blank_start]Superficial[blank_end] to internal intercostals
- [blank_start]Inspiration[blank_end]
- Direction of muscle fibres [blank_start]inferior[blank_end] and [blank_start]medial[blank_end]/[blank_start]anterior[blank_end]
2. Internal intercostals
- [blank_start]Deep[blank_end] to external intercostals
- [blank_start]Forced expiration[blank_end]
- Direction of muscle fibres [blank_start]inferior[blank_end] and [blank_start]lateral[blank_end]/[blank_start]posterior[blank_end]
[blank_start]Accessory Muscles[blank_end] - Used during [blank_start]forced inspiration or expiration[blank_end]
- Muscles attached to clavicles or ribs, e.g. [blank_start]Abdominal muscles[blank_end]- ADiaphragm
- BIntercostals
- CAccessory muscles
- DDiaphragm
- Einferior
- Fthoracic cavity
- Gthoracic floor
- HSkeletal
- IPhrenic
- JContracts
- KIntercostals
- Lbetween the ribs
- MSuperficial
- NInspiration
- Oinferior
- Panterior
- Qmedial
- RDeep
- SForced expiration
- Tinferior
- Uposterior
- Vlateral
- Wforced inspiration or expiration
- XAbdominal muscles
- YAccessory Muscles
35Pleura
- [blank_start]Serous[blank_end] membranes line body cavities and secrete [blank_start]serous fluid[blank_end]
- Within the thoracic cavity, these [blank_start]serous[blank_end] membranes are called the ‘[blank_start]pleura[blank_end]’
- [blank_start]Visceral pleura[blank_end] - covers lungs
- [blank_start]Parietal pleura[blank_end] - lines thoracic wall, [blank_start]mediastinum[blank_end]
- ‘[blank_start]Pleural[blank_end] cavity’ potential space between the membranes, contains [blank_start]serous fluid[blank_end] (~2mL), allows low-friction [blank_start]movement[blank_end] of lungs, Reduces [blank_start]surface tension[blank_end] and adhesion
- [blank_start]Parietal[blank_end] pleura attached to thoracic wall ([blank_start]fixed[blank_end]) therefore, thoracic wall movement = [blank_start]lung movement[blank_end]- ASerous
- Bserous fluid
- Cserous
- Dpleura
- EVisceral pleura
- FParietal pleura
- Gmediastinum
- HPleural
- Iserous fluid
- Jmovement
- Ksurface tension
- LParietal
- Mfixed
- Nlung movement
36Inspiration requires alveoli pressure [blank_start]lower[blank_end] than atmospheric pressure
[blank_start]Contract[blank_end] respiratory muscles → [blank_start]increase[blank_end] thorax size ([blank_start]volume[blank_end]) → [blank_start]decrease[blank_end] alveolar pressure → air flows [blank_start]in[blank_end] = inspiration
The diaphragm [blank_start]contracts concentrically[blank_end], [blank_start]flatness[blank_end] inferiorly, [blank_start]increases[blank_end] the [blank_start]vertical[blank_end] dimension and therefore the [blank_start]volume[blank_end] of the thoracic cavity.
1. [blank_start]Diaphragm[blank_end] = [blank_start]increase[blank_end] thoracic cavity [blank_start]length[blank_end]
2. [blank_start]External intercostals[blank_end] = [blank_start]increase[blank_end] thoracic cavity [blank_start]diameter[blank_end]/volume
3. [blank_start]Accessory muscles[blank_end] = "[blank_start]top up[blank_end]" lungs, when required ([blank_start]forced[blank_end] breathing)
Expiration is mostly a [blank_start]passive[blank_end] process therefore [blank_start]less[blank_end] energy is used. Cartilage and elastin tissue for [blank_start]recoil[blank_end] (i.e. ‘spring back’). Requires alveolar pressure [blank_start]higher[blank_end] than atmospheric pressure.
[blank_start]Relaxation[blank_end] of respiratory muscles → [blank_start]decrease[blank_end] thorax size ([blank_start]volume[blank_end]) → [blank_start]increase[blank_end] alveoli pressure → air flows [blank_start]out[blank_end] = expiration
If more expiration is needed, forced expiration can be assisted by [blank_start]internal intercostals[blank_end] and abdominal muscles by [blank_start]decreasing[blank_end] the thorax size (volume) further.- Alower
- BContract
- Cincrease
- Dvolume
- Edecrease
- Fin
- Gcontracts concentrically
- Hflattens
- Ivertical
- Jincreases
- Kvolume
- LDiaphragm
- Mvertically
- Nincrease
- OExternal intercostals
- Pincrease
- Qdiameter
- RAccessory muscles
- Sforced
- Ttop up
- Upassive
- Vless
- Wrecoil
- Xhigher
- YRelaxation
- Zdecrease
- AAvolume
- ABincrease
- ACout
- ADinternal intercostals
- AEdecreasing
37Respiration is a series of steps
1. [blank_start]Ventilation[blank_end]: Process of moving air into and out of the lungs. Supply [blank_start]O2[blank_end] to and remove [blank_start]CO2[blank_end] from the [blank_start]alveoli[blank_end] → [blank_start]Bulk Flow[blank_end]
2. [blank_start]Gas Exchange[blank_end]: Exchange of [blank_start]O2 and CO2[blank_end] across [blank_start]alveolar membrane[blank_end] (air to blood i.e. into body) → [blank_start]Diffusion[blank_end]
3. [blank_start]Gas transport[blank_end]: Deliver [blank_start]O2[blank_end] from lungs to tissues and and transport [blank_start]CO2[blank_end] produced by [blank_start]metabolism[blank_end] to lungs. (Cardiorespiratory) → [blank_start]Bulk Flow[blank_end]
4. [blank_start]Gas Exchange[blank_end]: Exchange of [blank_start]O2 and CO2[blank_end] between the [blank_start]capillaries[blank_end] and the [blank_start]cells[blank_end] → [blank_start]Diffusion[blank_end]
5. [blank_start]Cellular respiration[blank_end]: Cells use [blank_start]O2[blank_end] and produce [blank_start]CO2[blank_end] → [blank_start]Metabolism[blank_end]
Functions of the respiratory system
- Provide [blank_start]oxygen[blank_end], Eliminate [blank_start]carbon dioxide[blank_end]
- [blank_start]Cleans, warms and humidifies[blank_end] the air we breathe
- [blank_start]Communication[blank_end] (sound)
- Sense of [blank_start]smell[blank_end] - Regulate the [blank_start]pH[blank_end] of the blood, in association with the kidney - Defend against [blank_start]microbes[blank_end] - [blank_start]Temperature[blank_end] regulation
Daltons Law
Partial Pressure = [blank_start]fraction[blank_end] of individual gas x [blank_start]total gas pressure[blank_end]- AVentilation
- BO2
- CCO2
- Dalveoli
- EBulk Flow
- FGas Exchange
- GO2 and CO2
- Halveolar membrane
- IDiffusion
- JGas transport
- KO2
- LCO2
- Mmetabolism
- NBulk Flow
- OGas Exchange
- PO2 and CO2
- Qcapillaries
- Rcells
- SDiffusion
- TCellular respiration
- UO2
- VCO2
- WMetabolism
- Xo2
- Yco2
- ZCleans, warms and humidifies
- AACommunication
- ABsmell
- ACpH
- ADantigens
- AETemperature
- AFfraction
- AGtotal gas pressure
38F - [blank_start]Fraction of gas[blank_end] in a mixture
f - Respiratory [blank_start]frequency[blank_end]
I - [blank_start]Inhaled/inspired[blank_end]
E - [blank_start]Exhaled[blank_end]
V - [blank_start]Volume[blank_end]
VE Dot over quantity - Amount occurring in one minute (= [blank_start]exhaled volume in one minute[blank_end])
A – [blank_start]Alveolar[blank_end]
a – [blank_start]Arterial[blank_end]
c – [blank_start]Capillary[blank_end]
v – [blank_start]Venous[blank_end]
B - [blank_start]Barometric[blank_end]
D - [blank_start]Dead space[blank_end]
P - [blank_start]Pressure[blank_end] (PB = [blank_start]Barometric pressure[blank_end])
Px - [blank_start]Pressure[blank_end] exerted by [blank_start]gas X[blank_end]T - Pertaining to [blank_start]tidal volume[blank_end]
PAO2 = [blank_start]Pressure[blank_end] of [blank_start]oxygen[blank_end] in the [blank_start]alveolus[blank_end]
PvO2 = [blank_start]Pressure[blank_end] of [blank_start]oxygen[blank_end] in the [blank_start]venous blood[blank_end]
PaCO2 = [blank_start]Pressure[blank_end] of [blank_start]carbon dioxide[blank_end] in the [blank_start]arterial blood[blank_end]
VT = [blank_start]Tidal volume[blank_end]- AFraction of gas
- Bfrequency
- Cinhaled
- Dexhaled
- EVolume
- Fexhaled volume in one minute
- GAlveolar
- HArterial
- ICapillary
- JVenous
- KBarometric
- LDead space
- MPressure
- NBarometric pressure
- OPressure
- Pgas X
- Qtidal volume
- RPressure
- Soxygen
- Talveolus
- UPressure
- Voxygen
- Wvenous blood
- XPressure
- Ycarbon dioxide
- Zarterial blood
- AATidal volume
39Lung and chest wall separated by [blank_start]intra-pleural[blank_end] space. Lung has tendency to recoil [blank_start]inwards[blank_end] and Chest wall tends to expand [blank_start]outwards[blank_end] i.e they [blank_start]pull away from[blank_end] each other. Intrapleural pressure is [blank_start]sub atmospheric[blank_end] ~ -5 cm H2O. Alveolar pressure is [blank_start]atmospheric[blank_end] (i.e. 0 cm H20) [blank_start]Transpulmonary[blank_end] pressure is what distends the lung
Change [blank_start]transpulmonary[blank_end] pressure → change lung [blank_start]volume[blank_end].- Aintra-pleural
- Binwards
- Coutwards
- Dpull away from
- Esub atmospheric
- Fatmospheric
- GTranspulmonary
- Htranspulmonary
- Ivolume
40Work of Breathing
Need to do work to generate a big enough [blank_start]pressure[blank_end] gradient to:
1. [blank_start]Expand[blank_end] chest / lungs - need to overcome: [blank_start]Stiffness[blank_end] / elasticity of lung/chest wall AND Effects of [blank_start]surface tension[blank_end] → How hard is it to [blank_start]expand lungs[blank_end]?
2. Overcome airways [blank_start]resistance[blank_end] i.e. friction → How hard is it to [blank_start]move the air[blank_end]?
Lung “stiffness”, [blank_start]Compliance[blank_end] (CL), is a measure of how [blank_start]easy[blank_end] it is to change lung [blank_start]volume[blank_end]. Emphysema causes lungs to be [blank_start]more[blank_end] compliant, fibrosis causes lunges to be [blank_start]less[blank_end] compliant. Lower compliance needs [blank_start]more[blank_end] work to expand. Fluid lining alveoli exerts [blank_start]surface tension[blank_end] which causes them to [blank_start]contract[blank_end] thus resist [blank_start]expansion[blank_end]
→ need to overcome this force to [blank_start]expand[blank_end] lung.
Surfactant [blank_start]reduces[blank_end] surface tension in alveoli i.e makes them [blank_start]easier[blank_end] to expand
- Produced by [blank_start]alveolar type II[blank_end] cells
- Major constituent is [blank_start]phospholipids[blank_end]
- [blank_start]Lowers[blank_end] surface tension by [blank_start]reducing[blank_end] attractive forces between fluid molecules lining alveoli
- Lack of [blank_start]surfactant[blank_end]/failure to produce adequate surfactant → “[blank_start]stiff[blank_end]” lungs. e.g. Surfactant is absent in premature infants results in the development of [blank_start]respiratory distress syndrome[blank_end] (RDS)- Apressure
- BExpand
- CStiffness
- Dsurface tension
- Eexpand lungs
- Fmove the air
- Gresistance
- HCompliance
- Ivolume
- Jeasy
- Kmore
- Lless
- Mmore
- Nsurface tension
- Ocontract
- Pexpansion
- Qexpand
- Rreduces
- Seasier
- Talveolar type II
- Uphospholipids
- VLowers
- Wreducing
- Xsurfactant
- Ystiff
- Zrespiratory distress syndrome
41Airways Resistance
Air flow is mainly [blank_start]laminar[blank_end] flow during quiet breathing
Resistance to flow determined by Poiseuille’s Law
R = [blank_start]8nl / πr^4[blank_end]
Where: n = [blank_start]viscosity[blank_end]; l = [blank_start]length[blank_end]; r = [blank_start]radius[blank_end]
Broncho[blank_start]constriction[blank_end] / broncho[blank_start]dilation[blank_end] are important elements in airways resistance (e.g. asthma)
Main area of airway resistance = [blank_start]BRONCHI[blank_end]. Most of the resistance to airflow arises in the [blank_start]upper[blank_end] airway and the first 6 generations of the [blank_start]lower[blank_end] airway. The [blank_start]small[blank_end] airways contribute very little to airways resistance as they have a much [blank_start]larger[blank_end] cross sectional area.- Alaminar
- B8nl / πr^4
- Cviscosity
- Dlength
- Eradius
- Fconstriction
- Gdilation
- HBRONCHI
- Iupper
- Jlower
- Ksmall
- Llarger
42Measurement of Lung Function
(Pulmonary Function tests, Lung Function tests)
1. [blank_start]Spirometry[blank_end]
Lung [blank_start]volumes[blank_end] – How [blank_start]much[blank_end]?
[blank_start]Air flow[blank_end] rates – How [blank_start]fast[blank_end]?
2. [blank_start]Peak Expiratory Flow Rates[blank_end] (PEFR)- Avolumes
- Bmuch
- CAir flow
- Dfast
- EPeak Expiratory Flow Rates
- FSpirometry
43Spirometry: How Much?
Divide the air in lungs into four volumes:
1. [blank_start]Tidal volume[blank_end] ~ [blank_start]500 ml[blank_end] (VT or TV). Volume of air moved in and out during normal quiet breath
2. [blank_start]Inspiratory reserve volume[blank_end] ~ [blank_start]3 L[blank_end] (IRV). Extra volume that can be inspired with [blank_start]maximal inhalation[blank_end] - external intercostal muscles.
3. [blank_start]Expiratory reserve volume[blank_end] ~ [blank_start]1.5 L[blank_end] (ERV). Extra volume that can be exhaled with [blank_start]maximal effort[blank_end] -
internal intercostal and abdominal muscles.
4. [blank_start]Residual volume[blank_end] ~ [blank_start]1.2 L[blank_end] (RV). Volume remaining in lungs after [blank_start]maximal exhalation[blank_end]. Can’t be measured by spirometry → [blank_start]helium dilution[blank_end].
Lung capacities
These volumes can then be grouped into capacities:
1. [blank_start]Vital capacity[blank_end] ~[blank_start]5L[blank_end]. Maximal breath in to maximal out = volume of air you can shift in/out of lungs
2. [blank_start]Total lung capacity[blank_end] ~[blank_start]6L[blank_end]. Total volume in lungs when maximally full = VC + RV
3. [blank_start]Inspiratory capacity[blank_end] – Tidal volume + IRV
4. [blank_start]Functional residual capacity[blank_end] ~[blank_start]2.5L[blank_end]. Volume at end of normal breath out (Equilibrium point for thorax / lungs)- ATidal volume
- B500ml
- CInspiratory reserve volume
- D3L
- Emaximal inhalation
- FExpiratory reserve volume
- G1.5L
- Hmaximal exhalation
- IResidual volume
- J1.2L
- Kmaximal exhalation
- Lhelium dilution
- MVital capacity
- N5L
- OTotal lung capacity
- P6L
- QInspiratory capacity
- RFunctional residual capacity
- S2.5L
44Spirometry:
How Fast?
- Forced measurements give info about [blank_start]flow[blank_end]
- [blank_start]Forced Vital capacity[blank_end] FVC – maximum breath in to maximum breath out (VC) - forced out as hard as possible
- [blank_start]Forced expiratory volume[blank_end] in one second FEV1 i.e How much of FVC comes out in first second
- [blank_start]Reduced[blank_end] with diseases causing resistance to airflow (airways [blank_start]obstruction[blank_end] e.g. asthma) or small lungs
- FEV1/FVC ratio: Normal ~ [blank_start]80%[blank_end], [blank_start]< 0.70[blank_end] indicates airways obstruction
Spirometry can identify:
- [blank_start]Obstructive[blank_end] i.e. [blank_start]increases[blank_end] resistance to airflow e.g. Asthma, Chronic obstructive lung disease (Chronic bronchitis and Emphysema)
- [blank_start]Restrictive[blank_end] i.e. [blank_start]decreased[blank_end] lung volume, [blank_start]reduced[blank_end] lung capacity - reduced lung [blank_start]compliance[blank_end] e.g. fibrosis, chest-wall [blank_start]abnormalities[blank_end] e.g. respiratory muscle disease- Aflow
- BForced Vital capacity
- CForced expiratory volume
- DReduced
- Eobstruction
- F80%
- G<0.7
- HObstructive
- Iincreases
- JRestrictive
- Kreduced
- Lreduced
- Mcompliance
- Nabnormalities
45Volume of single breath = [blank_start]Tidal Volume[blank_end] = VT = [blank_start]500 ml (0.5L)[blank_end]Breathing rate = [blank_start]Frequency[blank_end] (f ) = ~[blank_start]10-12[blank_end]/minute
Total (mouth) ventilation = [blank_start]frequency[blank_end] x [blank_start]tidal volume[blank_end]
Some of the inhaled air never gets to the alveoli, just fills [blank_start]upper airways[blank_end], and is of no use for [blank_start]gas exchange[blank_end] – known as [blank_start]DEAD SPACE[blank_end] ( VD ) - about [blank_start]150ml[blank_end]
[blank_start]Alveolar ventilation[blank_end] (VA) measures the flow of gases that actually go into and out of the alveoli.
VA = [blank_start]frequency[blank_end] x ([blank_start]VT[blank_end] – [blank_start]VD[blank_end])
Slow, deep breathing [blank_start]increases[blank_end] VA and rapid, shallow breathing [blank_start]decreases[blank_end] VA ([blank_start]HYPO[blank_end]ventilation)- ATidal Volume
- BFrequency
- C0.5L
- D10-12
- Efrequency
- Ftidal volume
- Gupper airways
- Hgas exchange
- IDEAD SPACE
- J150ml
- KAlveolar ventilation
- Lfrequency
- MVT
- NVD
- Oincreases
- Pdecreases
- QHYPO
46Fick’s Law of Diffusion explains gas exchange through the membranes
F = [blank_start]A[blank_end]/[blank_start]T[blank_end] x [blank_start]D[blank_end]([blank_start]P1[blank_end]-[blank_start]P2[blank_end])
F = [blank_start]Flux[blank_end] (Amount flowing)
A = [blank_start]surface area[blank_end]
T = [blank_start]thickness[blank_end]
D = [blank_start]Diffusion constant[blank_end] or coefficient for substance depends on gas solubility (S)
P1-P2 = [blank_start]pressure difference[blank_end]
Emphysema is a disease characterised by [blank_start]dilation[blank_end] of the alveolar spaces and [blank_start]destruction[blank_end] of the alveolar walls. Since there is a [blank_start]decrease[blank_end] in the surface area of the lung (A) in emphysema, Fick’s law helps understand why patients with emphysema have [blank_start]decreased[blank_end] PO2 in blood
Pulmonary fibrosis involves [blank_start]thickening[blank_end] and scarring of the alveolar membranes – can arise from chronic inflammation, drugs, industrial chemicals. Since there is an [blank_start]increase[blank_end] in the thickness of the alveoli (T) in pulmonary fibrosis, Fick’s law helps understand why such patients a [blank_start]decreased[blank_end] PO2 in blood.- AA
- BT
- CD
- DP1
- EP2
- FFlux
- Gsurface area
- Hthickness
- IDiffusion constant
- Jpressure difference
- Kdilation
- Ldestruction
- Mdecrease
- Ndecreased
- Othickening
- Pincrease
- Qdecreased
47Gas transfer by diffusion depends on:
- [blank_start]Alveolar area[blank_end] for diffusion (Emphysema)
- [blank_start]Thickness[blank_end] of [blank_start]alveolar[blank_end] membrane (Fibrosis)
BUT main factor is [blank_start]Pressure difference[blank_end] therefore set the [blank_start]alveolar[blank_end] end of the [blank_start]partial pressure[blank_end] diffusion gradient so can exchange [blank_start]O2[blank_end] into blood and [blank_start]CO2[blank_end] out of blood
Alveolar partial pressure of O2 (PAO2)
- PAO2 ~[blank_start]100[blank_end] mmHg, reduced from PB ([blank_start]159[blank_end] mmHg) by water vapour and CO2 in alveoli
- PAO2 depends on:
1. PIO2 of [blank_start]inspired air[blank_end]2. [blank_start]Alveolar ventilation[blank_end] VA
3. [blank_start]Oxygen consumption[blank_end] VO2
The atmospheric PO2 is usually [blank_start]constant[blank_end], so it is the balance between oxygen [blank_start]consumption[blank_end] and alveolar [blank_start]ventilation[blank_end] that is most important.
Alveolar partial pressure of CO2 (PCO2)
- PACO2 is kept constant at [blank_start]40[blank_end] mmHg
- PACO2 depends on:
1. PICO2 of [blank_start]inspired air[blank_end]2. [blank_start]Alveolar ventilation[blank_end] VA
3. Carbon dioxide [blank_start]production[blank_end] VCO2
Alveolar PCO2 is usually determined only by the balance between carbon dioxide [blank_start]production[blank_end] and alveolar [blank_start]ventilation[blank_end], because atmospheric PCO2 is [blank_start]negligible[blank_end].- AAlveolar area
- BThickness
- Calveolar
- DPressure difference
- Ealveolar
- Fpartial pressure
- GO2
- HCO2
- I100
- J159
- Kinspired air
- LAlveolar ventilation
- MOxygen consumption
- Nconstant
- Oconsumption
- Pventilation
- Q40
- Rinspired air
- SAlveolar ventilation
- Tproduction
- Uproduction
- Vventilation
- Wnegligible
48Standard Values:
Assume a PB = 760 mmHg
PO2 = [blank_start]159[blank_end] mmHg [= FIO2 x PB]
PIO2 = [blank_start]149[blank_end] mmHg
PAO2= [blank_start]100[blank_end] mmHg [= PIO2 – VO2/VA]
PaO2= [blank_start]100[blank_end] mmHg
PvO2 = [blank_start]40[blank_end] mmHg [What’s left after O2 used by cells]
PACO2 = [blank_start]40[blank_end] mmHg
PaCO2 = [blank_start]40[blank_end] mmHg
PvCO2 = [blank_start]46[blank_end] mmHg- A159
- B149
- C100
- D40
- E149
- F159
- G100
- H40
- I100
- J40
- K46
- L159
- M149
- N46
- O46
- P100
- Q40
- R46
- S159
- T149
- U40
- V46
- W100
- X159
- Y149
- Z40
- AA46
- AB100
- AC159
- AD149
- AE40
- AF46
- AG149
- AH159
- AI100
- AJ46
- AK100
- AL149
- AM159
- AN40
49O2 Transport
O2 is carried in the blood in two forms:
1. [blank_start]Dissolved O2[blank_end]2. Combined with [blank_start]haemoglobin[blank_end]
Dissolved O2
For each mmHg PO2 can only dissolve [blank_start]0.3 ml[blank_end] of O2 per 100ml of blood therefore arterial blood with PO2 ~100 mmHg contains only [blank_start]3 ml[blank_end] dissolved O2 / litre so dissolved O2 is very [blank_start]ineffective[blank_end] for O2 transport as we need about [blank_start]250 ml[blank_end] O2 /min) → Need to use [blank_start]Haemoglobin[blank_end] to carry O2
Combined with haemoglobin
O2 forms an [blank_start]easily[blank_end] reversible combination with Hb to give [blank_start]oxyhaemoglobin[blank_end]:
O2 + Hb ↔ HbO2
Binding depends on [blank_start]PO2[blank_end] → [blank_start]dissociation curve[blank_end] → saturation
O2 saturation of Hb is the [blank_start]percentage[blank_end] of the available binding sites that have [blank_start]O2[blank_end] attached.
Varies with [blank_start]PO2[blank_end]
Arterial blood: PaO2 = 100 mmHg → (SaO2) is ~ [blank_start]97[blank_end]%
Venous blood: PvO2 = 40 mmHg → (SvO2) is ~ [blank_start]75[blank_end]%
P50 is PO2 for which Hb is 50% saturated ~ [blank_start]25[blank_end] mmHg- ADissolved O2
- Bhaemoglobin
- C0.3ml
- D3ml
- Eineffective
- F250ml
- GHB
- Heasily
- Ioxyhaemoglobin
- JPO2
- Kdissociation curve
- Lpercentage
- MO2
- NPO2
- O97
- P75
- Q25
50PO2 / saturation relationship is [blank_start]sigmoidal[blank_end] NOT [blank_start]linear[blank_end] which has several advantages:
1. [blank_start]Upper flat[blank_end] part of the curve means [blank_start]moderate[blank_end] changes in [blank_start]PO2[blank_end] around the normal value (~100 mmHg) have only [blank_start]small[blank_end] effects on the % saturation and therefore the amount of [blank_start]O2[blank_end] carried by [blank_start]arterial[blank_end] blood i.e some [blank_start]reserve[blank_end] capacity
2. [blank_start]Steep[blank_end] part of curve at [blank_start]lower PO2[blank_end] helps with loading of [blank_start]Hb[blank_end] in lungs AND unloading of [blank_start]O2[blank_end] to the tissues. [blank_start]Small[blank_end] changes in [blank_start]PO2[blank_end] result in [blank_start]large[blank_end] changes in amount of [blank_start]O2[blank_end] bound to haemoglobin
O2 carrying capacity (How much O2 could the blood carry?)
The maximal amount of O2 that can be combined with Hb is called O2 carrying capacity i.e Amount of O2 carried when Hb 100% saturated
- Normal blood has about [blank_start]150[blank_end] g Hb / litre
- One gram of Hb can combine with [blank_start]1.34 ml[blank_end] O2
O2 capacity = [blank_start]1.34[blank_end] x [blank_start]150[blank_end] = [blank_start]200[blank_end] ml /litre of blood
How much O2 is in the blood?
O2 content = O2 capacity x saturation ( + dissolved)
= [blank_start]1.34[blank_end] x Hb x Sat/100 + [blank_start]0.03[blank_end] x PaO2- Asigmoidal
- Blinear
- CUpper flat
- Dmoderate
- EPO2
- Fsmall
- Greserve
- HO2
- Iarterial
- JSteep
- Klower PO2
- LHb
- MO2
- NSmall
- OPO2
- Plarge
- QO2
- R150
- S1.34ml
- T1.34
- U150
- V200
- W1.34
- X0.03
51[blank_start]Arterial[blank_end] - [blank_start]Venous[blank_end] O2 difference = amount of O2 extracted by tissues
[blank_start]Arterial[blank_end] content ([blank_start]200[blank_end] ml O2 /L blood) - [blank_start]Venous[blank_end] content ([blank_start]150[blank_end] ml O2 /L blood) = [blank_start]50[blank_end] ml O2 /L blood
CO = [blank_start]5[blank_end] L/min
Total O2 extracted by tissues = [blank_start]250[blank_end] ml/min ( VO2)
[blank_start]More[blank_end] oxygen is extracted and used by tissues when [blank_start]exercising[blank_end] so the a-v O2 difference will [blank_start]increase[blank_end].
Normal a - v difference = [blank_start]50[blank_end] ml O2/L blood
Exercise a - v difference might be [blank_start]150[blank_end] ml O2/L
Saturation curve has [blank_start]capacity[blank_end] to provide this extra O2 extraction → [blank_start]venous[blank_end] might only be [blank_start]35[blank_end]% saturated
If [blank_start]low[blank_end] Hb e.g. anaemia, may have problems because saturation curve stays [blank_start]same[blank_end] but O2 content [blank_start]reduced[blank_end]
→ can’t remove [blank_start]more[blank_end] oxygen than you start with- AArterial
- BVenous
- CArterial
- D200
- EVenous
- F150
- G50
- H5
- I250
- JMore
- Kexercising
- Lincrease
- M50
- N150
- Ocapacity
- Pvenous
- Q35
- Rlow
- Sthe same
- Treduced
- Umore
52Carbon dioxide transport
CO2 transported in 3 forms:
1. Dissolved in [blank_start]plasma[blank_end] - [blank_start]20[blank_end] times [blank_start]more[blank_end] soluble than O2 ([blank_start]10[blank_end]%)
2. As [blank_start]bicarbonate[blank_end] ([blank_start]70[blank_end]%)
3. Combined with [blank_start]proteins[blank_end] (Hb) as [blank_start]carbamino[blank_end] compounds ([blank_start]20[blank_end]%)- Aplasma
- B20
- Cmore
- D10
- Ebicarbonate
- F70
- Gproteins
- Hcarbamino
- I20
53O2-Hb dissociation curve varies with conditions to improve O2 uptake / delivery
Bohr Effect
[blank_start]Right[blank_end] shift in curve: [blank_start]Increased[blank_end] PCO2, [blank_start]Increased[blank_end] H+, [blank_start]Increased[blank_end] Temperature e.g. [blank_start]EXERCISE[blank_end]
[blank_start]High[blank_end] CO2 → [blank_start]unload[blank_end] O2
For any particular [blank_start]PO2[blank_end] will have [blank_start]lower[blank_end] Hb saturation and O2 content
[blank_start]Improves[blank_end] delivery of O2 by Hb which is what you want in exercising tissue
Haldane effect
- The general equation for the Haldane Effect is H+ + HbO2 ←→ H+Hb + O2 which primarily shows the Bohr effect. The [blank_start]oxygenation[blank_end] of Hb promotes dissociation of [blank_start]H+[blank_end] from [blank_start]Hb[blank_end], which shifts the bicarbonate buffer equilibrium CO2 + H2O → H2CO3 → H+ + HCO3− towards [blank_start]CO2[blank_end] formation so CO2 is released from RBCs
- [blank_start]Removing[blank_end] O2 from blood e.g [blank_start]metabolising[blank_end] tissue allows formation of H+-Hb which can bind [blank_start]more[blank_end] CO2
- In lung [blank_start]lots[blank_end] of O2, adds to [blank_start]Hb[blank_end], [blank_start]less[blank_end] CO2 can be stored as HCO3, [blank_start]leaves[blank_end] blood as [blank_start]CO2[blank_end], [blank_start]exhaled[blank_end]- ARight
- BIncreased
- CIncreased
- DIncreased
- EEXERCISE
- FHigh
- Gunload
- HPO2
- Ilower
- JImproves
- Koxygenation
- LH+
- MHb
- NCO2
- ORemoving
- Pmetabolising
- Qmore
- Rlots
- SHb
- Tless
- Uleaves
- VCO2
- Wexhaled
54Control of breathing
We need to maintain [blank_start]consistent[blank_end] normal levels of PaO2 and PaCO2 for metabolic and biochemical stability (e.g pH) but [blank_start]O2[blank_end] uptake and [blank_start]CO2[blank_end] production quite [blank_start]variable[blank_end]. [blank_start]PaO2[blank_end] and [blank_start]PaCO2[blank_end] are normally kept within [blank_start]close[blank_end] limits by tight control of [blank_start]ventilation[blank_end].
Control of breathing – three basic elements
1. [blank_start]Central control[blank_end] (p[blank_start]ons[blank_end], m[blank_start]edulla[blank_end], b[blank_start]rainstem[blank_end]) sets [blank_start]rhythm[blank_end] of breathing and coordinates [blank_start]sensors[blank_end] and [blank_start]effectors[blank_end] to maintain respiratory [blank_start]homeostasis[blank_end]
2. [blank_start]Sensors[blank_end] ([blank_start]Chemoreceptors[blank_end], [blank_start]Lung[blank_end] and other receptors) The respiratory centre receives a variety of [blank_start]neural[blank_end] and [blank_start]chemical[blank_end] inputs from [blank_start]central[blank_end] and [blank_start]peripheral[blank_end] receptors.
3. [blank_start]Effectors[blank_end] ([blank_start]Respiratory muscles[blank_end]) adjust [blank_start]ventilation[blank_end] if required.
Respiratory control centre
We are uncertain how the intrinsic [blank_start]rhythmicity[blank_end] of respiration arises:
1. [blank_start]Brainstem[blank_end] respiratory centres: Neurons located in [blank_start]pons[blank_end] and [blank_start]medulla[blank_end] control rhythmic nature of [blank_start]inspiration[blank_end] and [blank_start]expiration[blank_end].
2. [blank_start]Medullary[blank_end] respiratory centre
- potentially [blank_start]Rhythm[blank_end] generator
- [blank_start]Dorsal[blank_end] area respiratory group ([blank_start]inspiration[blank_end])
- [blank_start]Ventral[blank_end] area respiratory group (mainly [blank_start]expiration[blank_end])
3. Other parts of [blank_start]brainstem[blank_end] involved: [blank_start]Apneustic[blank_end] centre, fine tunes the output of [blank_start]inspiratoryneurons[blank_end]
4. [blank_start]Cortex[blank_end] can override or modify brainstem → [blank_start]voluntary[blank_end] control / [blank_start]emotion[blank_end]- Aconsistent
- Bvariable
- CO2
- DCO2
- EPaO2
- FPaCO2
- Gclose
- Hventilation
- ICentral control
- Jons
- Kedulla
- Lrainstem
- Mrhythm
- Nsensors
- Oeffectors
- Phomeostasis
- QSensors
- RChemoreceptors
- SLung
- Tneural
- Uchemical
- Vcentral
- Wperipheral
- XEffectors
- YRespiratory muscles
- Zventilation
- AArhythm
- ABBrainstem
- ACpons
- ADmedulla
- AEinspiration
- AFexpiration
- AGMedullary
- AHRhythm
- AIDorsal
- AJinspiration
- AKVentral
- ALexpiration
- AMApneustic
- ANbrainstem
- AOinspiratory neurons
- APCortex
- AQvoluntary
- ARemotion
55Central chemoreceptors are located in the [blank_start]medulla[blank_end] on the [blank_start]ventrolateral[blank_end] surface. They are sensitive to the [blank_start]PCO2[blank_end] but not [blank_start]PO2[blank_end] of blood. [blank_start]CO2[blank_end] diffuses out of the [blank_start]cerebral capillaries[blank_end] which change the [blank_start]pH[blank_end] of the ECF/[blank_start]CSF[blank_end] and the central chemoreceptors respond to this change.
Peripheral chemoreceptors are located in the [blank_start]carotid[blank_end] and [blank_start]aortic[blank_end] bodies. They respond to [blank_start]decreased[blank_end] arterial [blank_start]PO2[blank_end] with a limited response to [blank_start]PCO2[blank_end] changes. They are [blank_start]rapidly[blank_end] responding.- Amedulla
- Bventrolateral
- CPCO2
- DPO2
- ECO2
- Fcerebral capillaries
- GpH
- HCSF
- Icarotid
- Jaortic
- Kdecreased
- LPO2
- MPCO2
- Nrapidly
56Ventilatory response to [blank_start]CO2[blank_end] - main factor
1. [blank_start]PaCO2[blank_end] is the most important stimulus to ventilation. It is normally [blank_start]tightly[blank_end] controlled (+/-[blank_start]3[blank_end] mmHg)
2. Most of the stimulus comes from the [blank_start]central[blank_end] chemoreceptors. [blank_start]Peripheral[blank_end] chemoreceptors also contribute to an extent.
3. Limits breath holding as increasing [blank_start]PaCO2[blank_end] creates powerful drive to breathe
4. The ventilatory response to [blank_start]PCO2[blank_end] is reduced by [blank_start]sleep[blank_end], increasing [blank_start]age[blank_end], [blank_start]genetic[blank_end] factors, [blank_start]training[blank_end], drugs.
Ventilatory response to hypoxia (Low [blank_start]PO2[blank_end])
1. Only the [blank_start]peripheral[blank_end] chemoreceptors are involved
2. There is negligible control during [blank_start]normal[blank_end] conditions. We normally only get ventilatory response to hypoxia if [blank_start]PaO2[blank_end] levels below [blank_start]60[blank_end] mmHg but if if [blank_start]CO2[blank_end] levels are [blank_start]high[blank_end] then ventilation is stimulated at [blank_start]PaO2[blank_end] levels above [blank_start]60[blank_end] mmHg, i.e. hypercapnic.
4. Hypoxic control becomes important at [blank_start]high altitude[blank_end], and in long-term hypoxemia caused by chronic lung disease
Non-chemical control of breathing
1. Receptors located in the airways and lungs connected to respiratory centres via [blank_start]vagus[blank_end] nerve
2. [blank_start]Lung[blank_end] receptors
- [blank_start]Stretch[blank_end]: Lung distension
- [blank_start]Irritants[blank_end]: Smoke, dust, cold air
3. Other receptors
- N[blank_start]ose[blank_end]/[blank_start]upper airway[blank_end]
- J[blank_start]oint[blank_end]/[blank_start]muscle[blank_end]
- A[blank_start]rterial baroreceptors[blank_end]
- P[blank_start]ain[blank_end] and t[blank_start]emperature[blank_end]- ACO2
- BPO2
- CPaCO2
- Dtightly
- E3
- Fcentral
- GPeripheral
- HPaCO2
- IPCO2
- Jsleep
- Kage
- Lgenetic
- Mtraining
- Nperipheral
- Onormal
- PPaO2
- Q60
- RCO2
- Shigh
- TPaO2
- U60
- Vhigh altitude
- Wvagus
- XLung
- YStretch
- ZIrritants
- AAose
- ABupper airway
- ACmuscle
- ADoint
- AErterial baroreceptors
- AFain
- AGemperature
57The heart is two pumps in [blank_start]series[blank_end]. The left and right pumps contract [blank_start]simultaneously[blank_end].
The cardiac cycle is defined by the [blank_start]contraction[blank_end] ([blank_start]systole[blank_end]) and [blank_start]relaxation[blank_end] ([blank_start]diastole[blank_end]) of the heart in a single ‘heart beat’. The heart spends [blank_start]2/3[blank_end] of the time in [blank_start]diastole[blank_end]. Blood pressure is measured by the [blank_start]highest[blank_end] pressure created by [blank_start]systole[blank_end] and the [blank_start]lowest[blank_end] pressure maintained at [blank_start]diastole[blank_end].
Atria contract [blank_start]before[blank_end] ventricles but most of the filling of the ventricles occurs [blank_start]passively[blank_end]. Ventricular contraction leads to [blank_start]ejection[blank_end] of blood from the heart and [blank_start]pressurises[blank_end] the arterial system. The [blank_start]left[blank_end] pump (ventricle) is more powerful than the [blank_start]right[blank_end] pump but the blood flow is the [blank_start]same[blank_end].- Aseries
- Bsimultaneously
- Ccontraction
- Dsystole
- Erelaxation
- Fdiastole
- G2/3
- Hdiastole
- Ihighest
- Jsystole
- Klowest
- Ldiastole
- Mbefore
- Npassively
- Oejection
- Ppressurises
- Qleft
- Rright
- Ssame
58Cellular mechanism of cardiac contraction
1. Increase in cytosolic [blank_start]Ca2+[blank_end] levels
2. [blank_start]Actin[blank_end] binding site revealed, [blank_start]Myosin[blank_end] forms cross bridges
3. [blank_start]Actin and myosin[blank_end] filaments slide, [blank_start]sarcomere[blank_end] shortens, force is generated
4. Every [blank_start]myocyte[blank_end] is activated every heartbeat. Therefore to increase the force of cardiac contraction, [blank_start]increase[blank_end] cytosolic [blank_start]Ca2+[blank_end] level which in turn [blank_start]increases[blank_end] the number of cross bridges formed and the force of contraction.
5. Cardiac [blank_start]relaxation[blank_end]: [blank_start]ATP[blank_end] binds to [blank_start]myosin[blank_end], [blank_start]decrease[blank_end] in cytosolic [blank_start]Ca2+[blank_end] levels, cross bridges [blank_start]release[blank_end]. All cardiac myocytes [blank_start]relax[blank_end] each heartbeat.
Anatomical basis of cardiac contraction
1. Cardiac muscle fibres in [blank_start]helical[blank_end] pattern
2. Heart [blank_start]twists[blank_end] and contorts as it contracts- ACa2+
- BActin
- CMyosin
- DActin and myosin
- Esarcomere
- Fmyocyte
- Gincrease
- HCa2+
- Iincreases
- Jrelaxation
- KATP
- Lmyosin
- Mdecrease
- NCa2+
- Orelease
- Prelax
- Qhelical
- Rtwists
59Pulsatile blood flow in [blank_start]arteries[blank_end] – continuous flow in [blank_start]capillaries[blank_end]
- [blank_start]Intermittent[blank_end] injection of blood into [blank_start]aorta[blank_end] from the [blank_start]left[blank_end] ventricle
- [blank_start]Elastic[blank_end] arteries : [blank_start]stretches[blank_end] then recoils, storing and [blank_start]releasing[blank_end] energy
- Cycles of increase ([blank_start]systolic[blank_end]) and decease ([blank_start]diastolic[blank_end]) pressure
- Pulse wave is a [blank_start]pressure[blank_end] wave, travels along the arteries, [blank_start]ahead of[blank_end] the blood- Aarteries
- Bcapillaries
- CIntermittent
- Daorta
- Eleft
- FElastic
- Gstretches
- Hreleasing
- Isystolic
- Jdiastolic
- Kpressure
- Lahead of
60Contractile cells [blank_start]99%[blank_end] of heart: typical [blank_start]striated[blank_end], [blank_start]lots of actin and myosin[blank_end], [blank_start]contractile power[blank_end]
Electrical cells [blank_start]1%[blank_end] of heart: [blank_start]specific areas[blank_end], [blank_start]pale[blank_end] in appearance, [blank_start]less striated[blank_end], [blank_start]hardly any actin and myosin[blank_end], [blank_start]very fast electrical conduction[blank_end]
Electrical signal in heart starts in [blank_start]SAN Sinoatrial Node[blank_end], moves between cells via [blank_start]conduction cells[blank_end], these [blank_start]conduction cells[blank_end] are in communication with each other but also with [blank_start]contractile cells[blank_end] nearby so contractile signals are spread through all heart. This all happens in [blank_start]ONE DIRECTION[blank_end]. In a [blank_start]contractile[blank_end] cell, this causes [blank_start]increased cytosolic Ca2+ level[blank_end], [blank_start]cross bridge formation and contraction[blank_end]
[blank_start]Intercalated disks[blank_end] exist between adjacent cells in heart. These have pores ([blank_start]gap junctions[blank_end]) which bridge cells and allow [blank_start]ions like Ca2+[blank_end] to move between them which activates cells all down the line.
[blank_start]All[blank_end] cells in the heart have gap junctions but [blank_start]electrical[blank_end] cells have [blank_start]more[blank_end] intercalated disks and [blank_start]more[blank_end] gap junctions and [blank_start]no[blank_end] actin and myosin to slow down the signal moving.
Gap junctions:
Along conduction pathway i.e. [blank_start]electrical cell to electrical cell[blank_end] ([blank_start]very fast[blank_end])
[blank_start]Between electrical and contractile cells[blank_end][blank_start]Between contractile cells[blank_end] ([blank_start]slower[blank_end])
All cells then act [blank_start]as one[blank_end] → [blank_start]a functional syncytium[blank_end] → whole heart can contract and relax [blank_start]at the same time[blank_end]- A99%
- B50%
- C1%
- D2/3
- E1/3
- Fstriated
- Gun-striated
- Hlots of actin and myosin
- Ihardly any actin and myosin
- Jcontractile power
- Kvery fast electrical conduction
- Lvery fast contraction
- Mno electrical conduction
- N1%
- O99%
- P50%
- Q2/3
- R1/3
- Sspecific areas
- Tspread randomly through heart
- Upale
- Vdark
- Wpatchy
- Xless striated
- Ymore striated
- Zun-striated
- AAvery striated
- ABhardly any actin and myosin
- AClots of actin and myosin
- ADno actin and myosin
- AEno actin and myosin
- AFvery fast electrical conduction
- AGcontractile power
- AHvery fast contraction
- AIno electrical conduction
- AJSAN Sinoatrial Node
- AKAV Node
- ALPurkinje Fibres
- AMCoronary Sinus
- ANBrainstem
- AOconduction cells
- APcontractile cells
- AQconduction cells
- ARcontractile cells
- ASnerves
- ATnerves
- AUcontractile cells
- AVconduction cells
- AWOne Direction
- AXBoyzone
- AYTake That
- AZWestlife
- BAcontractile
- BBconduction
- BCincreased cytosolic Ca2+ level
- BDdecreased cytosolic Ca2+ level
- BEincreased ATP level
- BFdecreased ATP level
- BGcross bridge formation and contraction
- BHcross bridge release and relaxation
- BIcross bridge formation and relaxation
- BJcross bridge release and contraction
- BKIntercalated disks
- BLIntercellular nerves
- BMInteratrial fibres
- BNInterislander ferries
- BOgap junctions
- BPdesmosomes
- BQtight junctions
- BRions like Ca2+
- BSfluid and nutrients
- BTblood flow
- BUsmall particles
- BVAll
- BWElectrical
- BXContractile
- BYelectrical
- BZcontractile
- CAmore
- CBfewer
- CCno
- CDmore
- CEfewer
- CFno
- CGno
- CHmore
- CIfewer
- CJBetween electrical cells
- CKBetween electrical and contractile cells
- CLBetween contractile cells
- CMvery fast
- CNfast
- COslower
- CPvery slow
- CQBetween electrical and contractile cells
- CRBetween electrical cells
- CSBetween contractile cells
- CTBetween contractile cells
- CUBetween electrical cells
- CVBetween electrical and contractile cells
- CWslower
- CXvery slow
- CYfast
- CZvery fast
- DAas one
- DBindependently
- DCa functional syncytium
- DDa practical synagog
- DEan operative symposium
- DFa simple synonym
- DGat the same time
- DHin its own time
61Electrocardiogram ECG
‘Lead’ - virtual line between two surface electrodes
A single lead detects a difference between electrodes
Depolarisation = [blank_start]contraction[blank_end]
Repolarisation = [blank_start]relaxation[blank_end]
P wave
Electrical event: [blank_start]SAN pulse[blank_end], [blank_start]Atrial depolarisation[blank_end]
Mechanical event: [blank_start]Atrial contraction[blank_end]
QRS
Electrical event: [blank_start]ventricular depolarisation[blank_end], [blank_start]atrial repolarisation[blank_end]
Mechanical event: [blank_start]ventricular contraction[blank_end]
Physical event: [blank_start]ejection of blood[blank_end]
T wave
Electrical event: [blank_start]ventricular repolarisation[blank_end]
Mechanical event: [blank_start]ventricular relaxation[blank_end]
Physical event: [blank_start]AV valves open, filling of ventricles[blank_end]- Acontraction
- Brelaxation
- Crelaxation
- Dcontraction
- ESAN pulse
- FAV pulse
- GIV pulse
- HHIS pulse
- IAtrial depolarisation
- JAtrial repolarisation
- KVentricular depolarisation
- LVentricular repolarisation
- MAtrial contraction
- NAtrial relaxation
- OVentricular contraction
- PVentricular relaxation
- Qventricular depolarisation
- Ratrial depolarisation
- Sventricular repolarisation
- Tatrial repolarisation
- Uatrial depolarisation
- Vventricular repolarisation
- Wventricular depolarisation
- Xatrial repolarisation
- Yventricular contraction
- Zventricular relaxation
- AAatrial contraction
- ABsemilunar valves open, ejection of blood
- ACAV valves open, filling of atria
- ADAV valves open, filling of ventricles
- AEsemilunar valves open, influx of blood
- AFventricular repolarisation
- AGventricular depolarisation
- AHatrial repolarisation
- AIatrial contraction
- AJventricular relaxation
- AKventricular contraction
- ALatrial contraction
- AMatrial relaxation
- ANAV valves open, filling of ventricles
- AOAV valves open, filling of atria
- APsemilunar valves open, ejection of blood
- AQsemilunar valves open, influx of blood
62Four structures make up the core of the electrical conduction system of the heart:
1. [blank_start]Sinoatrial[blank_end] ([blank_start]SA[blank_end]) node
2. [blank_start]Atrioventricular[blank_end] ([blank_start]AV[blank_end]) node
3. [blank_start]AV bundle[blank_end] ([blank_start]bundle of His[blank_end])
4. [blank_start]Subendocardial branches[blank_end] ([blank_start]Purkinje fibres[blank_end])
The normal cardiac impulse that initiates [blank_start]mechanical[blank_end] contraction of the heart arises in the [blank_start]SA node[blank_end] or pacemaker, located just beneath the [blank_start]right atrial[blank_end] epicardium at its junction with the [blank_start]superior vena cava[blank_end]. Pacemaker cells in the node possess an intrinsic [blank_start]rhythm[blank_end] so they initiate impulses at [blank_start]regular[blank_end] intervals [blank_start]without[blank_end] any stimulation by nerve impulses from the brain. [blank_start]Nervous and hormonal[blank_end] regulation affects HR and the [blank_start]SA[blank_end] node generates a pace accordingly. The [blank_start]SA[blank_end] node will normally fire at an intrinsic rhythmical rate of [blank_start]70 to 75[blank_end] beats/min under resting conditions. If the [blank_start]SA[blank_end] node is unable to generate an impulse, pacemaker activity shifts to another [blank_start]excitable[blank_end] component of the conduction system, such as the [blank_start]AV[blank_end] node or [blank_start]Purkinje Fibres[blank_end]. These are [blank_start]ectopic[blank_end] pacemakers and though they fire rhythmically, they are much [blank_start]slower[blank_end] than the SA node ~[blank_start]40 to 60[blank_end] beats/min.
Each impulse generated at the [blank_start]SA[blank_end] node travels [blank_start]swiftly[blank_end] throughout the muscle fibres of [blank_start]both atria[blank_end]. An [blank_start]interatrial[blank_end] bundle of conducting fibres facilitates rapid conduction to the [blank_start]left[blank_end] atrium. Thus stimulated, the [blank_start]atria[blank_end] begin to [blank_start]contract[blank_end]. The action potential enters the [blank_start]AV node[blank_end] by way of [blank_start]three internodal bundles[blank_end] of conducting fibres. Conduction velocity is [blank_start]slow[blank_end] through the [blank_start]AV node[blank_end], allowing [blank_start]atrial contraction[blank_end] to finish before [blank_start]ventricular depolarisation[blank_end] occurs. Conduction velocity [blank_start]increases[blank_end] as the impulse is relayed through the [blank_start]AV bundle[blank_end] ([blank_start]bundle of His[blank_end]) into the [blank_start]ventricles[blank_end]. Here, right and left bundle [blank_start]branches[blank_end] and the [blank_start]subendocardial branches[blank_end] ([blank_start]Purkinje fibres[blank_end]) in which they terminate conduct the impulses throughout the muscle of [blank_start]both ventricles[blank_end], stimulating them to contract almost simultaneously.- ASinoatrial
- BSA
- CAtrioventricular
- DAV
- EAV bundle
- Fbundle of His
- GSubendocardial branches
- HPurkinje fibres
- Imechanical
- JSA node
- Kright atrial
- Lsuperior vena cava
- Mrhythm
- Nregular
- Owithout
- PNervous and hormonal
- QSA
- RSA
- S70 to 75
- TSA
- Uexcitable
- VAV
- WPurkinje Fibres
- Xectopic
- Yslower
- Z40 to 60
- AASA
- ABswiftly
- ACboth atria
- ADinteratrial
- AEleft
- AFatria
- AGcontract
- AHAV node
- AIthree internodal bundles
- AJslow
- AKAV node
- ALatrial contraction
- AMventricular depolarisation
- ANincreases
- AOAV bundle
- APbundle of His
- AQventricles
- ARbranches
- ASsubendocardial branches
- ATPurkinje fibres
- AUboth ventricles
63The [blank_start]left[blank_end] ventricle pressurises the systemic circulation so there is [blank_start]high[blank_end] pressure in the large systemic [blank_start]arteries[blank_end] which is linked to the ventricular [blank_start]contraction[blank_end] and ejection of blood from the heart. This pressure is pulsatile in major [blank_start]arteries[blank_end] ([blank_start]systolic[blank_end]/[blank_start]diastolic[blank_end]). The [blank_start]mean arterial blood pressure[blank_end] (MAP) driving force is an important determinant of blood flow. Blood pressure [blank_start]falls[blank_end] steeply across the microcirculation and the oscillatory nature is [blank_start]reduced[blank_end]. Blood pressure is very [blank_start]low[blank_end] in [blank_start]veins[blank_end] so there is a [blank_start]large[blank_end] difference in pressure (ΔP) between the arterial and venous sides which creates a driving force for blood flow.
- Aleft
- Bhigh
- Carteries
- Dcontraction
- Earteries
- Fsystolic
- Gdiastolic
- Hmean arterial blood pressure
- Ifalls
- Jreduced
- Kveins
- Llow
- Mlarge
64Blood flow in fills [blank_start]arteries[blank_end], [blank_start]increases[blank_end] arterial blood volume and [blank_start]increases[blank_end] arterial pressure. Blood flow out drains [blank_start]arteries[blank_end], [blank_start]decreases[blank_end] arterial blood volume and [blank_start]decreases[blank_end] arterial pressure. Arterial blood volume and pressure are determined by a [blank_start]balance[blank_end] between blood flow in and blood flow out.
Blood flow in is caused by ventricular [blank_start]contraction[blank_end] and the [blank_start]ejection[blank_end] of blood from the heart therefore this can be controlled by adjusting the [blank_start]cardiac output[blank_end]. Increasing [blank_start]cardiac output[blank_end] increases [blank_start]inflow[blank_end].
Blood flow out is controlled by the [blank_start]resistance[blank_end] of the arteries and capillary flow. Increasing [blank_start]resistance[blank_end] decreases [blank_start]outflow[blank_end].
[blank_start]Increasing[blank_end] inflow or [blank_start]decreasing[blank_end] outflow increase arterial volume and pressure.
[blank_start]Decreasing[blank_end] inflow or [blank_start]increasing[blank_end] outflow decrease arterial volume and pressure.
MAP = [blank_start]CO[blank_end] x [blank_start]TPR[blank_end]
Mean Arterial Pressure = [blank_start]Cardiac Output[blank_end] x [blank_start]Total Peripheral Resistance[blank_end]
Cardiac output is determined by [blank_start]stroke volume[blank_end] and [blank_start]heart rate[blank_end]
CO = [blank_start]SV[blank_end] x [blank_start]HR[blank_end]
The stroke volume is the end [blank_start]diastolic[blank_end] volume - the end [blank_start]systolic[blank_end] volume of the [blank_start]ventricles[blank_end]. Stroke volume of the right and left ventricles are [blank_start]the same[blank_end].- Aarteries
- Bincreases
- Cincreases
- Darteries
- Edecreases
- Fdecreases
- Gbalance
- Hcontraction
- Iejection
- Jcardiac output
- Kcardiac output
- Linflow
- Mresistance
- Nresistance
- Ooutflow
- PIncreasing
- Qdecreasing
- RDecreasing
- Sincreasing
- TCO
- UTPR
- VCardiac Output
- WTotal Peripheral Resistance
- Xstroke volume
- Yheart rate
- ZSV
- AAHR
- ABdiastolic
- ACsystolic
- ADventricles
- AEthe same
65Cardiac output is [blank_start]variable[blank_end] (e.g. change in exercise), can have changes in heart rate and/or stroke volume. Mean arterial pressure is [blank_start]tightly regulated[blank_end] within a narrow range. This is coordinated within the [blank_start]brainstem[blank_end] with [blank_start]Afferent[blank_end] input from both the CNS and PNS and [blank_start]efferent[blank_end] output to heart and vessels.
Cardiac Pressoreflexes Receptors sensitive to changes in pressure ([blank_start]baroreceptors[blank_end]) are located in two places near the heart: the [blank_start]aortic[blank_end] baroreceptors and [blank_start]carotid[blank_end] baroreceptors. These send [blank_start]afferent[blank_end] nerve fibres to [blank_start]cardiac control centres[blank_end] in the [blank_start]medulla oblongata[blank_end]. Baroreceptors operate with integrators in the [blank_start]cardiac control centers[blank_end] in negative feedback loops called pressoreflexes or baroreflexes that oppose changes in [blank_start]pressure[blank_end] by adjusting [blank_start]heart rate[blank_end].- Avariable
- Btightly regulated
- Cbrainstem
- DAfferent
- Eefferent
- Fbaroreceptors
- Gaortic
- Hcarotid
- Iafferent
- Jcardiac control centres
- Kmedulla oblongata
- Lcardiac control centers
- Mpressure
- Nheart rate
66Carotid Sinus Reflex: Sensory ([blank_start]afferent[blank_end]) fibres from carotid sinus baroreceptors run through the [blank_start]carotid sinus[blank_end] nerve and on through the [blank_start]glossopharyngeal[blank_end] nerve to an integrator area of the [blank_start]medulla[blank_end] called the [blank_start]cardiac control centre[blank_end].
Aortic Reflex: Sensory ([blank_start]afferent[blank_end]) nerve fibres extend from baroreceptors located in the wall of the arch of the aorta through the [blank_start]aortic[blank_end] nerve and then through the [blank_start]vagus[blank_end] nerve to terminate in the [blank_start]cardiac control centre[blank_end] of the [blank_start]medulla[blank_end].
If the integrators in the [blank_start]cardiac control centre[blank_end] detect an [blank_start]increase[blank_end] in blood pressure above the set point, then a correction signal is sent to the [blank_start]SA[blank_end] node by way of [blank_start]efferent parasympathetic[blank_end] fibres in the [blank_start]vagus[blank_end] nerve. [blank_start]ACh[blank_end] released by vagal fibres [blank_start]decreases[blank_end] the rate of [blank_start]SA[blank_end] node firing, thus [blank_start]decreasing[blank_end] the [blank_start]heart rate[blank_end] back toward the set point. The vagus is said to act as a brake on the heart, or [blank_start]vagal inhibition[blank_end]. This is a negative feedback loop.
A decrease in aortic or carotid blood pressure usually allows some [blank_start]acceleration[blank_end] of the heart by way of correction signals through the [blank_start]cardiac[blank_end] nerve.- Aafferent
- Bcarotid sinus
- Cglossopharyngeal
- Dmedulla
- Ecardiac control centre
- Fafferent
- Gaortic
- Hvagus
- Icardiac control centre
- Jmedulla
- Kcardiac control centre
- Lincrease
- MSA
- Nefferent parasympathetic
- Ovagus
- PACh
- Qdecreases
- RSA
- Sdecreasing
- Theart rate
- Uvagal inhibition
- Vacceleration
- Wcardiac
67The [blank_start]sinoatrial[blank_end] node normally initiates each heartbeat but various factors can and do change the rate of the heartbeat. One major modifier of [blank_start]sinoatrial[blank_end] node activity is the ratio of sympathetic and parasympathetic impulses conducted to the node per minute. The results of parasympathetic stimulation on the heart are [blank_start]inhibitory[blank_end] and are mediated by [blank_start]vagal[blank_end] release of [blank_start]acetylcholine[blank_end], whereas sympathetic ([blank_start]stimulatory[blank_end]) effects result from the release of [blank_start]norepinephrine[blank_end] at the distal end of the [blank_start]cardiac[blank_end] nerve.
Other factors such as [blank_start]emotions[blank_end], [blank_start]exercise[blank_end], [blank_start]hormones[blank_end], [blank_start]blood temperature[blank_end], [blank_start]pain[blank_end], and stimulation of various exteroceptors also influence heart rate. Anxiety, fear, and anger often make the heart beat [blank_start]faster[blank_end]. Grief, in contrast, tends to [blank_start]slow[blank_end] it. During exercise the heart normally [blank_start]accelerates[blank_end]. The mechanism for this acceleration is not definitely known, but it is thought to include impulses from the [blank_start]cerebrum[blank_end] through the [blank_start]hypothalamus[blank_end] to the [blank_start]cardiac centre[blank_end]. [blank_start]Epinephrine[blank_end] is the hormone most noted as a cardiac accelerator. Increased blood temperature or stimulation of skin heat receptors tends to [blank_start]increase[blank_end] the heart rate, and decreased blood temperature or stimulation of skin cold receptors tends to [blank_start]slow[blank_end] it. Sudden, intense stimulation of pain receptors in visceral structures such as the gallbladder, ureters, or intestines can result in such [blank_start]slowing[blank_end] of the heart that fainting may result.- ASA
- BSA
- Cinhibitory
- DACh
- Estimulatory
- FNE
- Gvagal
- Hcardiac
- Iemotions
- Jexercise
- Khormones
- Lblood temperature
- Mpain
- Nfaster
- Oslow
- Paccelerates
- Qcerebrum
- Rhypothalamus
- Scardiac control centre
- TNE
- Uincrease
- Vslow
- Wslowing
68Reduction in vessel diameter caused by [blank_start]increased[blank_end] contraction of the muscular coat, or [blank_start]vasoconstriction[blank_end], [blank_start]increases[blank_end] resistance to blood flow, and thus blood flow into the tissue [blank_start]decreases[blank_end]. [blank_start]Vasodilation[blank_end], the increase in vessel diameter caused by [blank_start]relaxation[blank_end] of vascular muscles, [blank_start]decreases[blank_end] resistance to blood flow, and thus blood flow into the tissue [blank_start]increases[blank_end]. [blank_start]Small[blank_end] changes in diameter can cause proportionally [blank_start]large[blank_end] changes in resistance and therefore [blank_start]large[blank_end] changes in local blood flow. This makes the vasomotor mechanism well suited for [blank_start]quickly[blank_end] and [blank_start]dramatically[blank_end] changing blood flow under varying conditions in the body.
- Avasoconstriction
- Bincreases
- CVasodilation
- Dincreased
- Edecreases
- Frelaxation
- Gdecreases
- Hincreases
- ISmall
- Jlarge
- Klarge
- Lquickly
- Mdramatically
69Starling’s law states that the [blank_start]longer[blank_end] or more [blank_start]stretched[blank_end] the heart fibres are at the beginning of [blank_start]contraction[blank_end], the [blank_start]stronger[blank_end] the contraction and the [blank_start]larger[blank_end] the volume of blood ejected with each contraction. Thus, according to Starling’s law of the heart, the heart pumps out what it [blank_start]receives[blank_end].
Other factors that influence stroke volume are [blank_start]neural[blank_end] and [blank_start]endocrine[blank_end] chemical factors. Norepinephrine (NE) released by [blank_start]sympathetic[blank_end] fibres in the cardiac nerve and epinephrine released into the [blank_start]blood[blank_end] by the adrenal medulla can [blank_start]increase[blank_end] the strength of contraction of the myocardium which pushes [blank_start]more[blank_end] blood out of the heart per cardiac stroke, thus [blank_start]increasing[blank_end] the stroke volume and therefore cardiac output. Factors such as the stress of [blank_start]exercise[blank_end] can trigger these neural and endocrine responses.- Alonger
- Bstretched
- Ccontraction
- Dstronger
- Elarger
- Freceives
- Gneural
- Hendocrine
- Iincrease
- Jsympathetic
- Kblood
- Lmore
- Mincreasing
- Nexercise
70[blank_start]Low[blank_end] pressure is unable to control flow. [blank_start]High[blank_end] pressure has full control of flow.
Systemic circulation is designed in [blank_start]parallel[blank_end] so cardiac output is distributed between all organs through the continually [blank_start]branching[blank_end] arterial network.
During exercise, there is an [blank_start]increase[blank_end] in blood flow to muscles, heart and skin (except in maximal exercise). There is a [blank_start]decrease[blank_end] in blood flow to GI tract and kidneys. There is [blank_start]no change[blank_end] in blood flow to brain. This means the flow can [blank_start]vary[blank_end] depending on metabolic needs. There is [blank_start]increased[blank_end] CO but [blank_start]constant[blank_end] MAP therefore must be [blank_start]decreased[blank_end] TPR. Resistance also helps to control [blank_start]regional[blank_end] blood flows. Muscle, the heart and skin need [blank_start]increased[blank_end] flow so have [blank_start]decreased[blank_end] resistance. The GI tract and kidneys need [blank_start]decreased[blank_end] flow so have [blank_start]increased[blank_end] resistance. [blank_start]Arterioles[blank_end] are resistance vessels.
What controls vascular resistance
[blank_start]Local[blank_end]
[blank_start]Mechanical[blank_end] (response to force): from [blank_start]within[blank_end] the vessel (blood pressure) or from [blank_start]outside[blank_end] the vessel (e.g. swelling).
[blank_start]Central[blank_end]
[blank_start]Neural[blank_end]: Vascular sympathetic nerves
[blank_start]Humoral[blank_end] (blood): hormones released from remote organs e.g. adrenaline- ALow
- BHigh
- Cparallel
- Dbranching
- Eincrease
- Fdecrease
- Gno change
- Hvary
- Iincreased
- Jconstant
- Kdecreased
- Lregional
- Mincreased
- Ndecreased
- Odecreased
- Pincreased
- QArterioles
- RLocal
- SMechanical
- Twithin
- Uoutside
- VCentral
- WNeural
- XHumoral
71High vascular compliance means that blood tends to pool in [blank_start]veins[blank_end]. Most blood is found in [blank_start]small veins and venules[blank_end]
Small veins and venules: [blank_start]50[blank_end]%
Large veins: [blank_start]15[blank_end]%
Heart and lungs: [blank_start]15[blank_end]%
Arteries: [blank_start]15[blank_end]%
Capillaries: [blank_start]5[blank_end]%
Venous volume is [blank_start]larger[blank_end] than arterial volume. While supine, venous volume is [blank_start]uniform[blank_end] from head to toe. When upright, venous volume below the heart [blank_start]increases[blank_end]; whereas venous volume above the heart [blank_start]decreases[blank_end] causing extreme venous pooling in the [blank_start]legs and feet[blank_end]. [blank_start]Bicuspid[blank_end] venous [blank_start]valves[blank_end] in medium sized veins counteract venous pooling. The [blank_start]tone[blank_end] of surrounding tissue can also counteract venous pooling, particularly [blank_start]skeletal muscle[blank_end] which can alter its tensile state. Resting [blank_start]muscle tone[blank_end] varies between individuals. Muscle tone acts to [blank_start]stiffen[blank_end] the veins, making them [blank_start]less compliant[blank_end] therefore less prone to pooling. Muscle contractions [blank_start]increase[blank_end] venous blood flow and [blank_start]increased[blank_end] venous return means [blank_start]increased[blank_end] stroke volume.
Arterial puncture leads to a [blank_start]loss[blank_end] of arterial blood and a life-threatening fall in arterial [blank_start]pressure[blank_end] however there is a [blank_start]reserve[blank_end] of blood in the [blank_start]veins[blank_end]. When the brain detects a drop in arterial blood [blank_start]pressure[blank_end], it sends a signal to the [blank_start]veins[blank_end] to [blank_start]venoconstrict[blank_end] which pushes the [blank_start]reserve[blank_end] of blood back to the heart then over to the arteries to bring arterial pressure back [blank_start]up[blank_end].- Aveins
- Bsmall veins and venules
- C50
- D15
- E15
- F15
- G5
- Hlarger
- Iuniform
- Jincreases
- Kdecreases
- Llegs and feet
- MBicuspid
- Nvalves
- Otone
- Pskeletal muscle
- Qmuscle tone
- Rstiffen
- Sless compliant
- Tincrease
- Uincreased
- Vincreased
- Wloss
- Xpressure
- Yreserve
- Zveins
- AApressure
- ABveins
- ACvenoconstrict
- ADreserve
- AEup
Information
- Description
- Quiz on HUBS Cardiovascular , created by Juliet S on 02/08/2018.
- Author
- Juliet S
- Language
- English
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