Session 4 - The Heart Flashcards
Describe the anatomy of the tricuspid and mitral valve:
Cusps? Composition? Flexibility? What are the cusps attached to? What is also attached to this? Name of the cords? What muscle acts on the cords?
Tri - 3 Mitral - 2 Fibrous tissue covered with endothelium Very flexible Ring of fibrous tissue Myocardium Cordi tendini Papillary muscle
Describe the anatomy of the pulmonary and aortic valves:
Cusps?
Made of?
Form between?
The free edges are?
3
Fibrous tissue
Ventricle - Artery
Thick
At what phase in the cardiac cycle do coronary arteries fill? Why?
What happens?
Flows through CA during diastole
High -> Low pressure
Pressure in the CA on the surface of the heart is initially lower so these will fill with blood
Most of CA are inside the myocardium where the pressure is highest so these will be squeezed empty
Blood cannot flow from the surface arteries into the myocardium so there is no flow
During ventricular diastole the pressure in the aorta is high, pressure in the myocardium drops to zero now the coronary arteries inside the muscle can fill so flow occurs
Diastole - flows through CA
Pressure is lower on surface so CA fill
CA inside the myocardium are squeezed due to high pressure - during systole
The diastole pressure in aorta is highest and low in myocardium so blood can flow into the coronary arteries
Describe the conducting system of the heart and its function
What’s special about the four fibrous rings?
Where does contraction start?
Where do the purkinje fibres extend to?
How many times do the fibres divide?
They form a complete electrical isolation of the ventricles from the atria
Conducting system starts at the atrioventricular node - which is in the atrial septum
From the atrio-ventricular node modified myocardium (purkinje fibres) extends into the ventricular
septum and travels down to the apex of the heart
In the ventricular septum it divides twice to
provide a right bundle to the right ventricle and two bundles (an anterior and posterior) for the
left ventricle
What is the blood supply of the sinoatrial node and the atrioventricular node?
Where does the posterior interventricular artery arise from?
The sino-atrial node is supplied by the right coronary artery in 60% of hearts
and the left in 40%.
The atrioventricular node is supplied by the posterior interventricular artery in all hearts
Right coronary artery
What is the location of the sinoatrial node?
Crista terminalis (a ridge of tissue on the
inside between the right atrium and right atrial appendage) just where the superior vena
cava enters the right atrium.
On a chest X-ray which chambers and vessels form the right and left borders of the
cardiac shadow?
Right heart border; right atrium
Left heart border; left auricular appendage superiorly and the left ventricle
