Anatomy of the heart Flashcards
How many vales
4 valves; 2 pairs
The 2 atrioventricular valves between atrium and ventricle
The two semilunar valves between the ventricles and pulmonary arteries/veins
Right AV valve
Tricuspid valve
Left AV valve
Biscuspid (mitral) valve
Function of the AV valve
To contract when P builds up in the ventricles to prevent the backflow of blood into the atrium
Diastole (filling phase)
When blood moves from atrium to ventricles
- AV valves are open
- Semilunar valves are closed to prevent backflow of blood in the pulm art/vs
Systole (contractile phase)
P builds in ventricles
- AV valves close
- When P is built, semilun vales open
Semilunar valves function
Prevent blood returning to ventricles during
filling (diastole)
Semilun valves
Right side - Pulmonary (semilunar) valve, 3 cusps.
Left side - Aortic (semilunar) valve, 3 cusps.
What seperates the RHS and LHS of the heart?
The intraventricular septum
What happens during Sytole?
The papillary muscle pull on the chordae tendineae
Function of the chordae tendineae
To gently pull the large AV flaps when the pap muscle first contracts to prevent the valves from folding back into the atrium during V systole pressure
What is the first branch of Systemic circulation
To the myocardium tissue, branches from the Aorta called cardiac circulation
Right coronary artery
Branches from the ascending Aorta, runs in a groove between the Right atrium and Ventricle in the epicardial layer, to the pos, it branches into smaller that run into myocardial layer
- Supply mostly ventricles
How does the left coronary artery run
Behind the pulm artery and branches into two other arteries
- Circumflex artery and Anterior interventricular artery
Where does the circumflex artery run
Towards the back
Where does the interventricular artery run?
Between the interven septum anteriorly
What drains the blood from the right coronary artery?
The small cardiac vein
What drains the blood from the left coronary arteries?
Great cardiac vein
Where does the small and great Cardiac veins drain?
In the coronary sinus (a chamber) which empties directly in the right atrium
How many RBCs can pass through a capillary wall
One cell at a time in single file
What kind of muscle is cardiac muscle?
Striated
Why is the cytoplamsm of a cap wall thin?
To allow gas exchange over the shortest distance possible
Features of the cardiac muscle
Features of both smooth & skeletal muscle as well as cardiac muscle specific specialisations.
Structure of the cardiac muscle cell
Striated
* Short, branched cells.
* 0ne (or occasionally 2) nuclei / cell.
* Central (oval shaped), nucleus.
* Cytoplasmic organelles packed at the poles
of nucleus.
* Interconnected with neighboring cells via intercalated disks (ICDs).
Adhesion belts
(linking actin to actin) ~Vertical portion, transmits force allowing other cells to contract
Desmosomes
(linking cytokeratin with cytokeratin). As the cells contract, the sarcomeres move away from each other so the desmosomes anchor them together
Gap junctions
(electrochemical communication) ~ Horizontal portion, layer fused and Ca2+ together, release of Ca2+ which travels from cells to cell through junctions and innervates other cells
What does the conduction system of the heart do?
Ensures that the heart beats in its set rhythm
Features of conduction system
Its actions greatly increase the efficiency of heart pumping.
* This system is responsible for the co-ordination of heart
contraction and of atrioventricular valve action eg pathway to the pap to contract chordae to prep for P build
* Autonomic nerves alter the rate of conduction impulse
generation eg sym and parasym activity of modifies muscle cells
Conduction system pathway
Sinoatrial node (SA node) –> internodal pathways –> atrioventricular bundle –> R + L bundle branches –> purkinje fibres that terminate in the capillary walls
What activates the SA node
If no input from nerves, then it activates through its own tone
Where are the internodal pathways found
Across the right and left atriums
What does the AV node do
Allow completion of filling phase
What does the AV bundle split into
R + L bundles
Features of the conduction cells
(some) Peripheral myofibrils.
Central nucleus,
mitochondria, glycogen
lots of gap junctions
some desmosomes & few adhesion belts.
1% of cardiac cells
