Venous Return

Question 1

Name the 5 mechanisms involved in venous return

Answer 1

Skeletal Muscle Pump
Pocket Valves
Smooth Muscle
Respiratory Pump
Gravity

Question 1

What does Starling’s Law state?

Answer 1

Venous return = stroke volume

Question 2

How does the skeletal muscle pump work?

Answer 2

Repeated muscle contractions squeeze and compress blood through the veins and back to the heart

Question 3

Why do athletes do an active cool down?

Answer 3

This ensures that high amounts blood is still returned back to the heart despite fewer and less frequent muscle contractions

Question 4

How do pocket valves work?

Answer 4

As the blood is forced up through the vein,pocket valves form a closure which prevents the back flow of blood

Question 5

How does smooth muscle work?

Answer 5

It surrounds the valves and contracts and constricts,helping pump blood upwards through the valves and veins back to the heart

Smooth muscle is found in the walls of veins and contracts involuntarily to assist venous return. These gentle, rhythmic contractions help squeeze blood through the veins and push it back toward the heart, especially from the lower body. During exercise, sympathetic nervous activity increases, causing vasoconstriction of smooth muscle in the veins, which improves venous tone and aids the return of blood to the heart. This mechanism works alongside the skeletal muscle pump and respiratory pump to maintain cardiac output during activity.

Question 6

How does the respiratory pump work?

Answer 6

Constant breathing in and out causes continuous changes in thoracic pressure which itself squeezes blood back to heart through compression of veins

Question 7

How does gravity work in venous return?

Answer 7

When blood is pushed out to places above the heart (heads/arms) gravity pulls the blood back down and back to the heart
This is the reason why athletes often lay on their back and raise their legs upwards after exercise

Question 8

What is the primary purpose of the venous return mechanisms?

Answer 8

Increase the amount of blood that returns back to the heart

Question 9

Explain the process by which proves Starling’s Law

Answer 9

Increased exercise-increase venous return-heart fills up with more blood-heart muscle is elastic so it stretches-a more powerful contraction of the heart is needed-more powerful contraction-increased stroke volume/ejection fraction