Flashcards
Pump it! - The Cardiovascular System
Cards in this deck (100)
- 1THE CARDIOVASCULAR SYSTEM: functions to transport materials to and from cells. connects every cell in the body ¯\_(ツ)_/¯PUMP= heart
MEDIUM = blood
CONDUCTING SYSTEM = vessels - 2Pulmonary Circuit (LOW Pressure) *Carries blood to and from the lungs for gas exchange.*R Ventricle -> Pulmonary Artery -> Lungs -> Pulmonary Vein -> L Atrium -->> SYSTEMIC CIRCUIT
- 3Systemic Circuit (HIGH pressure) *carries oxygenated blood from heart to the rest of the body*L Ventricle -> Aorta -> body ->
superior / inferior vena cava // coronary sinus -> R Atrium ---> PULMONARY CIRCUIT - 4Heart <3Heart rests within the thoracic cavity, on diaphragm in the MEDIASTINUM. Heart is a socialist, sits LEFT.
- 5Pericardial Sac/PericardiumDouble membrane fibrous sac. Filled with serous fluid to reduce friction. Anchors and cushions heart, keeps it in place.
OUTER LAYER = parietal pericardium
INNER LAYER = visceral layer / epicardium. This layer is attached to the outer layer of heart. - 6The outer layer of the PericardiumParietal Pericardium
- 7The inner layer of the pericardiumvisceral / epicardium
attached to OUTER layer of the heart - 8Heart Wall (3 Layers)epicardium (= visceral layer of serous pericardium)
myocardium (=cardiac muscle tissue - pump action)
endocardium (= endothelial lining, continuous with great vessels) - 9myocardiumcardiomyocytes / cardiac muscle
single central nuclear connected via gap junctions & desmosomes.
high aerobic capacity,
intercalated discs maintain structure, enhance connections, conduct action potentials. - 10heart anatomyGreat veins and arteries at top of heart (the flat "base")
Bottom of heart is pointy apex.
- 11Coronary SulcusDivides Atria fromVentricles
- 12Interventricular SulcusSeparates the ventricles
- 13AtriaReceives blood into the heart
(top chamber) - 14VentriclesPumps blood from heart
(bottom chamber)
L Ventricle => blood to body
R Ventricle => blood to lungs - 15Interatrial SeptumSeparates atria
- 16Connective Tissue Septum Separates muscles of atria and ventricles - why?To isolate the electrical impulses and to ensure the impulse runs on the right track
- 17Fossa Ovalisa shallow depression where the foramen oval was located
- 18AuricleFlap of expandable atrium visible when not filled
- 19Blood flow through heart: BLOOD ENTERS via Right Atrium from: Superior/Inferior Vena Cava + Coronary Sinus.R Atrium -> AV Valve-> R Ventricle -> Pulmonary Trunk -> Pulmonary Arteries -> LUNGS -> pulmonary veins -> L Atrium -> AV Valve -> L Ventricle -> BODY - > S&I Vena Cava/Coronary Sinus-> R Atrium
- 20heart Valves prevent back flow of blood. (AV ventricle to aorta, SL artery o heart) (NO VALVES BETWEEN VEINS AND ATRIA)Atrioventricular Valves (AV) sit between atria and ventricle
Right = Tricuspid
Left = Bicuspid
Semilunar Valves sit at base of aorta and pulmonary artery between ventricles and vessels. - 21How is the opening and closing of the valves controlled?Valve opens when pressure in Atria is greater than pressure in Ventricle.
Valve close when Pressure in Ventricles is greater than pressure in Atria.
(pA>pV=OPEN => pV>pA=CLOSE) - 22CORONARY CIRCULATION - how do we get oxygen and nutrients to the heart itself? coronary arteries spread over the heart the Coronary Sinus brings deoxygenated blood back to the atria ...Coronary arteries branch of ascending aorta. they FILL on diastole (ventricles relaxed)
Carry oxygenated blood to myocardium.
Pulsatile blood flow, little flow in systole. Arteries recoil when ventricles relax. Mediates pressure, blood keeps moving. - 23Autorhythmic Fibres (found in SA node, AV node, AV Bundle, Bundle Branches and Purkinje Fibres)Autorhythmic Fibres spontaneously generate action potentials, conduct action potentials along system pass on to contractile fibres.
- 24Contractile Fibres Atria contract and relax together Ventricles contract and relax together99% of all muscle fibres do the mechanical work.
Heart tissue is excitable -> the spread of electrical activity through intercalated discs-desmosomes and gap junctions enables contraction in unison (Syncytium) - 25Conducting SystemSinoatrial node (SA Node)
Atrioventricular Node (AV Node)
AV Bundle
R&L Bundle Branches
Purkinje Fibres - 26Sinoatrial NodeSA Node - Pace Maker
Spontaneously depolarises
sets the basic rhythm (80-100 bp/m)
can be modified by neurotransmitters - 27Atrioventricular NodeAV Node - slight delay
spontaneously depolarises (40-60 bp/m)
the delay enables the atria to fully contract in order to fill ventricle before electrical activity arrives at ventricle and causes ventricular contraction. - 28Autorhythmic CellsAutorhythmic cells have special ion channels for the action potentials.
There is a spontaneous depolarisation and the membrane is constantly drifting towards threshold.
There is a long refractory period (plateau) and then depolarisation.
prevents tetany - 29Sequence of Events1. SA node mass of cells (pacemaker) generates AP spontaneously
2. Stimulus spreads across atria and reaches AV node
3. AV Nodal delay = atria contracts before ventricle
4. AP spreads along AV bundle fibres and Purkinje Fibres
5. AP relayed across ventricles, Ventricles contract - 30Criteria for Efficient Pumping organised by intertribal pathway, internal pathway and AV nodal pathwayAtria Must Contract before Ventricles
Coordinate excitation so that each heart chamber contracts as a syncytium
Atria contract together, Ventricles contract together - 31Cardiac CycleAtrial contraction (atrial systole) -> Atrial relaxation (Atrial diastole) -> Ventricular Contraction (ventricular systole) -> Ventricular Relaxation *Ventricular diastole)
Atrial diastole is quite lengthly to allow atria to fill as no valves from vein-> atria
Ventricular systole shorter than diastole. - 32Electrocardiogram - summation of APs occurring in heartP Wave = Atrial depolarisation
PR= AV nodal delay, atria contracting
QRS = Ventricular Depolarisation
ST= Ventricles contract and empty
T Wave = Ventricular depolarisation
TP= heart at rest, atria filling - 33end diastolic volume (EDV)volume of blood in each ventricle at the end of ventricular diastole.
affected by filling time, duration of ventricular diastole, venous return (blood flow during ventricular diastole). - 34end systolic volume (ESV)Volume of blood remaining in each ventricle at the end of ventricular systole (~40% of EDV)
Preload -> ↑ preload = ↓ ESV
contractility -> force during contraction at given preload (influenced by hormones, PSNS, SNS) - 35Stroke Volume (SV) Most important factor in the Cardiac CycleVolume of blood pumped out of each ventricle during a beat. SV = EDV - ESV
- 36Ejection Fraction% of EDV represented by SV
- 37Cardiac Output (CO)volume pumped by left ventricle in one minute (CO = HR x SV)
Dynamic - can be affected by ANS and hormones - 38heart rate = autonomic innervation of the heartboth SNS and PNS
Medulla oblongata
Cardioaccelatory Centre ↑HR SNS
Cardioinhibitory Centre ↓HR PNS
Reflex pathways, baroreceptors, chemoreceptors (CNS)
brain stem has both ↑↓ centres - 39Autonomic ToneResting heart rate is slightly slower than rate set by node (pacemaker) because PNS slows it slightly - changes the membrane potential of the autorhythmic cell.
- 40membrane potentialacetolcholyne means membrane repolarises for longer => takes longer to get to next threshold.
membrane potential may be brought closer to threshold ↑ rate of depolarisation - 41HORMONESadrenaline, noradrenaline and thyroid hormones ↑ HR (SA node)// contractile cells
- 42Atrial Reflex + Venous Returnadjustment to heart rate, depending on venous return. Stretch on right atrium walls triggers reflect to ↑ sympathetic activity => ↑ HR
Venous return affects nodal cells to ↑ HR - 43Preload and AfterloadPreload =degree of ventricular stretching. ↑ EDV = ↑ preload.
After load = tension ventricle produces to open semilunar valve to eject blood. Restricted by high BP, stiff arteries. ↑ force required = ↑ ESV - 44Blood VesselsArteries
Arterioles
Capillaries
Venues
Veins - 45which is what? veins?
- 46Arterial walls have three tunics: Tunica Interna - Inner TunicTunica Interna - inner layer
Endothelium
Basement Membrane
Internal Elastic Lamina - 47Arterial Walls have three tunics: Tunica Media - middle tunicTunica Media - middle layer - thickest layer
Elastic Fibres
Smooth Muscle
External Elastic Lamina (muscular arteries) - 48Arterial Walls have three tunics: Tunica Externa - outer tunicTunica Externa
Elastic and Collagen Fibres - 49About ArteriesArteries are elastic - they stretch and recoil
Largest diameter
Carry blood away from the heart
Tunica Media contains a large number of elastic fibre and store elastic energy, move blood during ventricular diastole - 50Muscular ArteriesMedium sized tunica media has a lot of smooth muscle - constrict and dilate.
Superficial Muscular arteries form pressure point to control bleeding or measure pulse. - 51Arterioles-small arteries deliver blood to capillaries
-active in vasoconstriction and vasodilation (SNS/Smooth Muscle) regulators of systemic vascular resistance - 52Metarteriolessupply capillary beds, no smooth muscle at distal end
"thoroughfare" can bypass capillary sphincter - 53Capillariesendothelial cells & basement membrane
Enormous surface area and thin barrier for effective diffusion.
Exchange nutrients and waste via interstitial fluid - 54True CapillaryEmerge from arterioles or metarterioles, flow regulated by a sphincter
- 55Continuous Capillaryuninterrupted lining
- 56Fenestrated CapillaryHave pores
fond in kidneys (kidney filters,
found in choroid plexus (CSF) of brain (blood brain barrier). - 57Sinusoidal CapillaryLarge fenestrations, specialised capillaries
Found in liver, spleen, bone marrow. - 58VenulesSmall veins formed from merging capillaries.
They go on to merge with other venues, and form veins. - 59Veins have 3 tunics.Tunica Interna - valves to prevent backflow
Tunica Media
Tunica Externa (thickest layer - collagen and elastic fibres)
Veins larger in diameter and have a thinner wall than arteries. Do not have the same recoil, "capacitance vessels" - 60blood flowa volume of blood that flows through a tissue p/unit time. it is dynamically regulated and and determined by blood pressure and resistance.
- 61Flow is proportional to change in pressure over resistanceFlow is inversely proportional to resistance
- 62Arterial Pressure120mmHg at Aorta
35mmHg at Capillary (arteriole end)
35-18mmHg at Capillary (venous end)
ΔP=~100mmHg - 63Pressure V ResistanceFor flow to occur, circulatory pressure must be > than total peripheral resistance
TPR is determined by vascular resistance, viscosity, turbulence. - 64vascular resistanceopposition to blood flow due to friction between blood and vessel wall.
=>↑ length ↑ resistance
↑ diameter of vessel ↓ resistance
inversely proportional to the 4th power of the radius of the lumen. - 65peripheral resistancehighest at arterioles, as they have an actively controlled radius due to vasoconstriction and vasodilation
- 66Turbulencesudden change in diameter of vessel (plaque deposits, clot) slows blood flow
- 67Viscosityratio of RBCs (haematocrit/ packed elements?) to plasma
- 68Velocity of Blood Flow is Inversely Related to Cross Sectional AreaVelocity decreases as blood flows from aorta to capillaries and increases as it flows from capillaries to veins up to the heart. It is slowest in the capillary for effective nutrient delivery.
- 69blood pressure measures pressures during ventricular contraction and relaxation~120 Systolic Pressure /
80 Diastolic Pressure - 70DiastolePassive process; the heart spends more time in diastole than systole
- 71systoleventricular contraction - active process
- 72Venous Pressure & Venous ReturnVenous Pressure is low
Resistance is low (veins have large diameter) and blood flow velocity is increasing as blood is returning to the heart. - 73Venous ReturnVolume of blood returning to the heart from systemic veins is maintained by
Pressure Gradient established y the Heart
the Skeletal Muscle Pump
Respiratory Pump
Valves - 74Capillary Pressure and Exchange MethodsDiffusion
Transcytocis (vesicular transport)
Bulk Flow (filtration and absorption) - 75Bulk Flow Capillary Exchange:Important for regulation of volumes of blood and interstitial fluid
osmotic and hydrostatic pressure balance determines how much fluid moves in or out of capillary - 76Hydrostatic PressurePressure blood exerts on the walls of the vessels (pushes fluid OUT)
- 77Osmotic PressureOpposes hydrostatic pressure.
Proteins in plasma not present in interstitial fluid draw water into plasma/capillary from the interstitial fluid (water moves from low c solute to high). - 78What does pressure do at the arteriole end of the capillary ?Pushes fluid out
- 79What does pressure do at the venue end of the capillary?Pushes fluid IN
- 80OedemaFluid accumulating in interstitial fluid due to an imbalance; related to R heart failure and valves not working. Venous Pressure increases, fluid not returning to capillaries.
- 81Homeostatic mechanisms maintain adequate blood flow to all tissues (PERFUSION)Primary homeostatic variable is MEAN ARTERIAL PRESSURE
MAP = COxTPR => ↑CO ↑TPR ↑MAP - 82Cardiovascular Regulation is regulated by Heart Rate and Stroke Volume3 Mechanisms;
Autoregulation
Neutral Mechanisms
Hormonal Mechanisms - 83Autoregulation:Local factors alter blood flow through capillaries via local dilators/constrictors
act on pre capillary sprinters to control blood flow through capillary bed exercise muscle: ↑CO2. Local vasodilation in muscle to ↑ blood flow to get rid of CO2 and access O2. - 84VasodilatorsLactic acid
histamine
nitric oxide - 85vasoconstrictorsprostaglandins from platelets
- 86Autoregulation Homeostasis ExampleStress, trauma, chemical change ↑ tissue activity.
Inadequate local pressure and blood flow
Local ↓ in resistance and ↑in blood flow.
Homeostasis! - 87Neural MechanismsControl via cardiac centres and vasomotor centres in medulla oblongata; vasomotor centres are areas that change blood vessel diameter, changing resistance.
- 88Cardiovascular Centreinput from all over the body, higher brain regions can change cardiovascular output.
- 89Proprioceptorsdetect movement and pressure in joints - linked to afferent system
- 90Baroreceptorsdetect blood pressure - located in aorta and carotid sinus
- 91Chemoreceptorsdetect changes in CO2 and O2
- 92Sympathetic Nervous SystemCardioacellerator Nerves ↑ Heart rate
Increases contractility
Vasomotor nerves => can cause vasoconstriction or vasodilation - 93Parasympathetic Nervus SystemVagus Nerve ↓ heart rate
- 94Baroreceptor ReflexWorks second by second to change blood pressure depending on what we are doing --> send impulses to CV centre when BP falls; BP receptors stretched less. CV Centre will ↑ CO, thus, BP will ↑
- 95Sympathetic System (can constrict or dilate vessels) For vasodilation...homeostasis disturbed
baroreceptors stimulated
cardioinhibitory centre stimulated // cardioaccelertory system inhibited
Vasodilation occurs
↓ Cardiac output
HOMEOSTASIS - 96Sympathetic System (can constrict or dilate vessels) For vasoconstrictionHomeostasis disturbed
baroreceptors inhibited
vasomotor centre stimulated // cardioaccelatory system stimulated
vasoconstriction
↑ Cardiac output
HOMEOSTASIS - 97Hormones & Cardiovascular RegulationEndocrine system provides long and short term regulation of Cardiovascular system.
adrenaline & noradrenaline from adrenal medulla increase cardiac output and peripheral vasoconstriction - 98homeostatic mechanisms regulate cardiovascular activity to ensure adequate perfusion to tissues:Determined by CO, TPR and MAP.
Regulated by local factors, neural and hormonal mechanisms. - 99Over time, CV system changes with long term trainingheart size ↑
Heart rate more efficient
SV and EDV ↑
CO ↑
Blood flow more effective
Blood Volume ↑ - 100During ExerciseCardiac output ↑ and blood flow %% changes to various organs and tissues. While the overall % to brain reduces, it still gets the same AMOUNT of blood.
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