Venous Return Mechanism

Question 1

What is venous return?

Answer 1

The process by which deoxygenated blood returns to the right atrium (via the vena cava)

Question 2

What does venous return depend on?

Answer 2

1) Gravity
2) Skeletal muscle pump
3) Respiratory pump
4) Pocket valves
5) Venomotor control

Question 3

How does gravity impact venous return?

Answer 3

Assists blood flow from body parts above the heart

Question 4

How does the skeletal muscle pump impact venous return?

Answer 4

Contracting muscles compress veins, forcing blood towards the heart

Question 5

How does the respiratory pump impact venous return?

Answer 5

> Relies on changes in thoracic and abdominal cavity pressure during inspiration and expiration
Pressure changes compress nearby veins and assist flow towards the heart

Question 6

How do pocket valves impact venous return?

Answer 6

To ensure that blood only flows in one direction (towards the heart)

Question 7

How does venomotor control impact venous return?

Answer 7

The limited capacity of veins to change their shape and therefore slightly increase venous return due to vasoconstriction

Question 8

Explain venous return during exercise

Answer 8

> Exercise increases venous return
Increased physical activity stretches the myocardium, making the heart contract with greater force

Question 9

What is Starling’s law of the heart?

Answer 9

As a larger volume of blood flows into the ventricles, the blood stretches the cardiac muscle fibres, leading to an increase in the force of contraction