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Cardiovascular System
Fichas del conjunto (46)
- 1Location of the heartLocated in the mediastinum
- 2Surfaces of the heartApex: formed by the tip of the ventricle, likes inferior anterior and to the left
Base: formed by the atria, lies superior, posterior and to the left (opposite of apex)
anterior surface: deep to the sternum and ribs
Inferior surface: lies against the diaphragm
Right surface: faces the right lung and extends from the inferior surface to the base
Left surface (pulmonary): faces the left lung, and extends from the base to the lungs - 3PericardiumThe heart is enclosed and protected by the pericardium
2 Parts of the pericardium:
1.Fibrous Pericardium (holds the heart in the mediastinum and determines stretch and filling)
2. Serous pericardium (protects the heart) -2 layers
I. Parietal layer: fused to the fibrous pericardium
II. Visceral layer (epicardium): tightly adheres to the heart
In between these two layers is a fluid filled pace called the serous cavity that contains serous fluid
This fluid protects against friction during contractions - 4Layers of the HeartPericardium
Epicardium
myocardium
Endocardium - 5AuriclesAuricles slightly increases the capacity of the atria so that they can hold greater volume of blood
- 6SulciOn the external surface of the heart we have grooves called sulci which contain coronary blood vessels and various amounts of fat
Each sulcus marks the external boundary between two chambers of the heart - 7Coronary SulcusEncircles most of the heart and marks the external boundary between the superior atria and inferior ventricles
- 8Anterior Interventricular SulcusMarks the external boundary between the right and left ventricles and it continues on the posterior side as the posterior interventricular sulcus
- 9Pectinate musclesMostly on the anterior wall of the right atria
Involved in increasing the power of contractions - 10Interatrial septumBetween the right and left atrium there is thin partition called the interatrial septum
In this septum is located a prominent depression called the fossa ovalis which is a remnant of the foramen oavle
The foramane ovale was an opening in the fetal heart that closed soon after birth - 11Tricuspid valve (right atrioventricular valve)Between the right atrium and heart
3 cusps
Connected to the chordae tendineae which is then connected to the papillary muscles (type of trabeculae carneae) - 12Bicuspid or mitral valveBetween the left atrium and heart
- 13Interventricular septumSeperates the right and left ventricles
- 14Blood flow on the right side of the heartDeoxygenated blood enters the right atrium through the superior/inferior vena cava/ coronary sinus
The blood flows into the right ventricle through the tricuspid valve and then enters the pulmonary trunk through the pulmonary valve
The pulmonary trunk separates into the right and left pulmonary arteries that carry deoxygenated blood to the lungs for oxygenation - 15Blood flow on the left sideOxygenated blood from the lungs enter the left atrium through the pulmonary veins and then goes through the tricuspid valve (mitral) into the left ventricle
From the left ventricle blood flows through the aortic valve into the ascending aorta
From some blood flows into the coronary arteries fr coronary circulation while the rest flows into the arch and descending aorta which the oxygenated blood to the rest of the body - 16Ductus ArteriorsusIn the fetal heart there is a temporary blood vessel that connect from the pulmonary trunk to the arch of the aorta called the ductus arteriosus which would pull most of the blood from the pulmonary trunk into the aorta to prevent too much blood flow to the still developing lungs
After birth this vessel closes and turns into the ligamentum arteriosum - 17Myocardial Thickness Throughout the heartThe myocardium wall thickness of the chambers will depend on the function
The atria have thinner walls since their pumping blood under lower pressure while the ventricles pump blood under higher pressure and greater distances
Even though both ventricles pump the same amount of blood at the same rate the left ventricle actual has a higher workload compared to the right
This is because the right ventricles pumps blood over a shorter distance to the lungs will less flow resistance and pressure whereas the left ventricle has to pump throughout the whole body with higher pressure and blood flow resistance
This means that the left ventricle has to work much harder than the right in order to maintain the same rate of blood flow
hence the reason why the left ventricle is the thickest chamber - 18Fibrous Skeleton of the heartFunctions
1. Provides a structural foundation
2. acts as an insulator between atria and ventricle
3. Prevents overstretching
4. Provides insertion points for bundles of cardiac muscles - 19Atrioventricular valvesBiscuspid (mitral) and tricuspid valves
Valves open and close in response to pressure changes
when there is higher pressure in the atria then the valves will be open
When the valves are open the cusps of the valves face inward into the ventricles, the papillary muscles are relaxed and the chordae tendinae are slack. The blood will be able to flow into the ventricle
Then the higher pressure in the ventricle pushes the cusps upward until the edges meet and close off the opening; the papillary muscles contracts and the chordae tendinae tighten.
If the papillary muscles or chordae tendinae are damaged, then the blood may be able to regurgitate (back flow) since the valves wont be able to open and close properly - 20Semilunar valvesPulmonary valve and aortic valve
Called semilunar since their made up of 3 crescent moon shaped cusps
When the semilunar valves are open the cusps face inward towards the arteries which happens when the ventricles have a higher pressure
When the ventricles relax then the blood starts to back flow which fills the cusps and closes them off - 21Prevention of back flow between atria and veinsThere are no valves between the atria and superior/inferior vena cava nor the pulmonary veins
When the atria contract the blood does back flow but it is controlled since the weak walls of the veins actual compress and collapse due to the pressure of the atria which prevents this back flow - 22Pulmonary and systemic circulationRight side: pulmonary circulation (towards lung)
Left side: systemic circulation (towards body) - 23Coronary circulationBlood supply directly to the myocardium of the heart from coronary arteries
The left and right coronary arteries encircle the heart like a crown
When the heart is contracting the coronary arteries are compressed, when it relaxes the high pressure in the aorta drives blood into the coronary arteries
The left and right coronary arteries branch off of the aorta
The left coronary artery branches into the circumflex artery and the anterior interventricular artery
The right coronary artery branches into the right marginal branch and the posterior interventricular artery - 24Circumflex arterySupplies O2 blood to the walls of the left atrium and left ventricle
- 25Anterior interventricular arterySupplies O2 blood to the walls of both ventricles
- 26Right marginal branchSupplies O2 blood to he wall of the right ventricle
- 27Posterior Interventricular arteryAlso supplies O2 blood to the walls of both ventricles
- 28Collateral circulationWhere two or more arteries supply a single organ or tissue are usually connected
These connections are called anastomoses which allow for collateral circulation
This is how the heart can still get sufficient O2 even if one of the coronary arteries are blocked - 29Coronary veinsAfter blood flows through the coronary arteries it flows into the capillaries of the myocardium where it delivers O2 and nutrients and picks of CO2 and wastes
This deoxygenated blood goes through the coronary veins and will eventually dump most of the deoxygenated blood into the coronary sinus of the right atrium
Great cardiac vein: located in the anterior interventricular sulcus and drain the areas of the heart provided by the left coronary artery (both ventricles and left atrium)
The middle cardiac vein: located in the posterior interventriclar sulcus and drains the areas of the heart supplied by the posterior interventricular artery (both ventricles)
small cardiac vein: located in the coronary sulcus and drains the right atrium and ventricle
anterior cardiac veins: drain the right ventricle and open directly into the right atrium as the coronary sinus from the posterior side - 30Histology of cardiac muscle tissueCardiac muscle is made up of Elongated branching cells that contain 1-2 centrally located nuclei
The fiber are connected together by transverse thickenings of the sarcolemma called intercalated disks which contain desmosomes that actually connect the fibers together
The gapjunstions allow for muscle action potentiasl to conduct from one muscle fiber to its neighbor; so electrically the cardiac muscle of atria and ventricle acts as a single unit
The sarcolemma contains actin thin filaments and myosin thick filaments
-I band contains Z disk and just actin
-A band contains M-line and actin and myosin
T-tubules are located ta the Z-disk
Sarcoplasmic reticulum is smaller (smaller reserve of calcium) - 31Autorhythmic fibresAre self excitable- their repeatedly generating action potentials that trigger contracts
They allow for the heart to contract even if its out of the body
Only 1% of cardiac fibers are autorhythemic and they have 2 main functions
1. to act as a pacemaker setting the rhythm of contractions
2. make up the conduction system - 32The cardiac conduction systemEnsures that the heart is contracting in a coordinated manner
Cardiac excitation normally begins in the SA node that's located in the right atrium right below the opening of the superior vena cava. The cells of SA node don't have a stable resting potential,instead they repeatedly depolarize to threshold. This spontaneous depolarization is called the pacemaker potential. Once the pacemaker potential reaches the threshold it triggers an action potential
Each AP of the SA node propagates throughout both atria via the gap junctions located in the intercalated disks. Following the AP both atria contract at the same time
By conduction along the atrial muscle fibers the AP reaches the AV node thats located in the interatrial septum below the coronary sinus
At the AV the AP slows down considerably; this delay provides time for the atria to empty their blood into the ventricle - 33SA nodeNatural pace maker of the heart
- 34Conduction system cont.From the AV node the AP reaches the AV bundle or the bundle of HIS which is the only location where conduction can occur from the atria to the ventricle since in all other areas the fibrous skeleton acts as insulator between the atria and ventricle
After propagation through the AV bundle, the AP enters both the right and left bundle branches which extend through the interventricular septum towards the apex
Finally the purkinje fibers rapidly conduct the AP starting at the apex up towards the rest of the ventricular myocardium
The ventricles will contract and push their blood towards the semilunar valves - 35Beats per minute for SA, AV nodes and purkinje fibersSA node: 100 beats per min
AV node: 40-60
Purkinje fibers: 20-35 - 36Refractory PeriodThe time where a second contraction cant be triggered- the refractory period is longer than the contraction itself
In heart muscle, tetanus (maintained contractions) do NOT occur
Absolute: cardiac muscle is completely insensitive to further stimulation
Relative: decreased sensitivity - 37EKGelectrical events of the myocardium can be correlated with mechanical events
- 38P waveAtrial Depolarization
- The horizontal line after the wave indicates atrial contraction (systole) - 39QRS complexVentricular depolarization
-the horizontal line after indicates ventricular contraction - 40P-Q intervalWhere the atria contracts, relaxes and the ventricle begins to contract
0.16 sec - 41T waveVentricular repolarization
-the horizontal line that follows indicates ventricular relaxation (diastole) - 42Q-T intervalVentricles contract and relax
Longer than P-Q interval
0.36 sec - 43Heart Sound4 Heart sounds but first 2 are only loud enough to be heard with a stethoscope
S1: is the sound of the AV valves closing; LUBB sound and its a bit louder and longer
S2: is the sound of the SL valves closing; DUBB sound - 44Cardiac Output (CO)CO is the volume of blood ejected out of the right or left ventricle and into the aorta or pulmonary trunk each MINUTE
CO= SV x HR - 453 factors that effect stroke volume1. Preload: the amount of stretch on ventricular walls
2. Contractility: the force of contraction created by ventricles
3. Afterload: the pressure that the contracting ventricles must produce in order to overcome the pressure in the aorta or pulmonary trunk (so we can move blood out of ventricles) - 46—
Información
- Descripción
- Year 1 Semester 2 Fichas sobre Cardiovascular System , creado por Raeesa Zulfiqar el 20/04/2017.
- Creado por
- Raeesa Zulfiqar · abr 2017
- Actualizado
- 22 abr 2017
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