1.5 Venous return

Question 1

What is venous return?

Answer 1

the flow of blood back to the heart via the veins and specifically the vena cava

Question 2

What happens to venous return during exercise?

Answer 2

increases
as a result stroke volume also increases

Question 3

What is the skeletal muscle pump?

Answer 3

muscles contracting and relaxing are constantly changing shape
results in muscles pressing on nearby veins
causes pumping action, pushing blood back to heart

Question 4

What is the respiratory pump?

Answer 4

breathing in and out causes contractions in many muscles as well as diaphragm
causes constant change in pressure of the thoracic cavity, compressing the veins, causing venous return

Question 5

What are pocket valves?

Answer 5

veins full of pocket valves
as blood passes through valves, they close to prevent back flow of blood

Question 6

What else aids venous return?

Answer 6

gravity - veins above heart assisted by gravity
smooth muscle - lines walls of veins so easier for blood to travel through
suction pump of heart - as heart releases and refills, low pressure generates ‘suction’ action, making easier to take blood from veins