Venous return

Question 1

Definition of venous return

Answer 1

The return of the blood to the right atria through the veins

Question 2

How does stroke volume depend on venous return

Answer 2

• Increased venous return means greater greater volume of blood returning to the heart and filling of blood in the ventricles
• this leads to a higher end diastolic volume and greater stretch on ventricle walls, ejecting higher volumes of blood from the heart, increasing SV
• this is also known as Starling’s law

Question 3

List mechanisms of venous return

Answer 3

Pocket valves

Smooth muscle

Gravity

Muscle pump

Respiratory pump

Question 3

What happens if venous return is higher

Answer 3

Greater volume of blood available in the ventricles for ejecting

Question 4

What are pocket valves

Answer 4

one way valves located in veins which prevent backflow

Question 5

What is smooth muscle

Answer 5

layer of smooth muscle in the vein wall vasoconstricts to create venomotor tone which aids movement of blood

Question 6

what is gravity in venous return

Answer 6

blood from upper body above the heart is helped to return by gravity

Question 7

What is a muscle pump

Answer 7

skeletal muscles contract during exercise and compress veins between them, squeezing blood back to the heart

Question 8

What is a respiratory pump

Answer 8

during inspiration and expiration, a pressure difference between the thoracic cavity and abdominal cavity is created, squeezing the blood back to the heart