Mechanisms of venous return

Question 1

State the 2 problems with maintaining venous return during exercise

Answer 1

Problem 1: the blood pressure in veins returning to the heart is 0.

Problem 2: most of the Q is in the leg so it has to travel against gravity to return to heart

Question 2

State the names of the 5 solutions which maintain venous return during exercise

Answer 2

1. pocket valves
2. skeletal muscle pump
3. smooth muscle
4. respiratory pump
5. gravity from above the heart

Question 3

What is the function of a pocket valve?

Answer 3

In larger veins to prevent the backflow of blood

Question 4

What is the function of a skeletal muscle pump?

Answer 4

When the lower leg muscles contract, getting wider and pressing against the vein walls. The blood is squeezed up towards the heart.

Question 5

What is the function smooth muscle?

Answer 5

The thin layer of smooth muscle in veins allows for vasoconstrictions move blood up towards heart

Question 6

What is the function of the respiratory pump?

Answer 6

During inspiration the diaphragm flattens, decreasing the volume and increasing pressure the abdomen (below pressure in thoracic cavity). This differential pressure pulls blood up towards heart.