Question

Describe movement of each heart valve caused by change in direction of flow of blood. What valves are open/closed during contraction and relaxation etc.

Answer 1

To describe the Heart valve opening and closure better, it should be correllated with the cardiac cycle

Each cardiac cycle consist of systole(contraction) and diastole(relaxation)

Each cardiac cycle is about 0.8 sec (0.3 sec systole and 0.5 sec diastole)

SYSTOLE (CONTRACTION)

It include mainly 2 phases

1)isovolumetric contraction

2)Rrapid ejection phase

3)Reduced ejection phase

DIASTOLE

1)Protodiastole

2)isovolumetric relaxation

3)rapid filling

4)reduced filling

Normally 70% of the ventricle are filled with blood duing the joint diastole.( ATRIOVENTRICULAR VALVE ARE OPEN)

Atria contract to push the remaining 30% of blood to the ventrcle this is Atrial systole .During this period the Atrioventricular valve(mitral and tricuspid) are open.

when the blood reaches the ventricle the AV valve will close. and the ventricle become a closed chamber chamber

The ventricle will contract isovolumetrically

it increases the pressure in the ventricle , that causes the opening of semilunar valves (aortic and pulmonary valve)

blood goes into aorta and pulmonary artery(rapid ejecetion phase and reduced ejection phase)

After that the semilunar valve closes (protodiastole)

ventricle relaxes as a closed chamber (isovolumetric relaxation)

It is followed by the opening of AV VALVE

Blood from the atria drain into venticle(rapid filling and reduced filling )

So, from this we can tell that

The AV valve closes before isovolumetric contraction

Opening of smeilunar valve at the end of Isovolumetric ocntraction

Closure of Semilunar valve in isovolumetric relaxation

opening of AV valve end of isovolumetric relaxation