VENOUS RETURN MECHANISMS

Question 1

What are the 5 mechanisms of venous return?

Answer 1

Pocket valves

Smooth muscle

Gravity

Muscle Pump

Respiratory system

Question 2

Where are pocket valves?

What do they prevent?

Answer 2

There are valves in the veins.

These valves prevent blood flowing the wrong way

Question 3

Where are smooth muscles?

What does smooth muscle do?

Answer 3

The vein has an inner wall made of smooth muscle

The muscle vasoconstricts (tightens and shrinks the diameter).This aids the movement of blood.

Question 4

What does gravity aid?

Answer 4

Blood in the upper body (above the heart) is aided by gravity on its return to the heart.

Question 5

What does the muscle pump do?

Answer 5

When exercising the muscles are contracting and compress against the veins.
This squeezes the vein and pushes blood back to the heart.

Question 6

Where is the Respiratory pump?

Answer 6

During the inspiration and expiration of breathing a pressure difference is created.

This occurs in the thoracic and abdominal cavity.

Question 7

What does the respiratory pump do?

Answer 7

This squeezes the blood back to the heart.

As breathing increases, so does respiratory rate. This in turn increases the respiratory pump.

Question 8

Explain the venous return mechanism?

Answer 8

When we have finished exercising our cardiac output is still high.

Because of decreased blood pressure at this time the vast quantity of blood struggles to return to the heart.

This can cause:
Light headedness
Blood pooling

This is why active recovery (cool down) is so important after exercise.