1.4 Function of The Heart

Question 1

How does the cardiac cycle take place?

Answer 1

1. Blood enters the two atria simultaneously.
2. Once each atrium is full, they contract which pushes the blood down into the ventricles through the tricuspid and bicuspid valves.
3. Once the ventricles are full, they contract in a squeezing action from the bottom to the top of the heart.
4. This forces blood up against the tricuspid and bicuspid valves, closing them.
5. Blood can only leave the heart through the semilunar valves, pulmonary arteries and the aorta.
6. Once blood has left the ventricles, they relax and open up again.
7. Back flow is prevented by the semilunar valves snapping shut.

Question 2

What are the ventricles contracting called?

Answer 2

Systole.

Question 3

What are the ventricles relaxing called?

Answer 3

Diastole.

Question 4

Why is the right ventricle wall less muscular than the left?

Answer 4

This prevents blood from entering the lungs under too much pressure. If this happened, water from the blood would be forced into the airspace, effectively drowning us.