7.4 & 7.5: The heart and the circulatory system

Question 1

Which side of the heart pumps deoxygenated blood?

Answer 1

the right side

Question 2

Which chamber of the heart is the thickest

and why

Answer 2

the left ventricle
it has to contract powerfully to pump blood around the body whereas the right ventricle only needs to pump blood to the lungs

Question 3

Why do the ventricles have thicker walls than the atria?

Answer 3

they need to pump blood out of the heart whereas the atria just need to push blood into the ventricles

Question 4

Atrioventricular valves

where and function

Answer 4

link the atria and ventricles and prevent the backflow of blood into the atria when the ventricles contract

Question 5

Semi-lunar valves

where and function

Answer 5

link the ventricles to the pulmonary artery and aorta and prevent the backflow of blood into the heart after the ventricles contract

Question 6

Cords?

Answer 6

the cords attach the AV valves to the ventricles to stop them being forced into the atria when the ventricles contract

Question 7

The cardiac cycle

Answer 7

the ongoing sequence of contraction and relaxation of the atria and ventricles which keep the blood continuously circulating around the body

Question 8

What changes when the atria and ventricles contract?

2

Answer 8

volume

pressure

Question 9

stages of the cardiac cycle

3

Answer 9

1. ventricles relax, atria contract
2. ventricles contract, atria relax
3. ventricles relax, atria relax