venous return

Question 1

what is venous return

Answer 1

term used for the volume of blood that returns to the RIGHT side of the heart via the venules and veins.

Question 2

what happens to venous return during exercise

Answer 2

Blood pressure (BP) in the veins is too low to maintain VR, so SV and Q decrease

The body needs extra help to push the blood against gravity and to increase VR and SV.

Question 3

what happens if venous return decreases

Answer 3

A decrease in stroke volume, which = a decrease in Q

Question 4

what happens if venous return increases

Answer 4

An increase in stroke volume, which = an increase in Q

Question 5

How does an increase in Venous Return affect ventricular contraction?

Answer 5

Increase in blood to right atrium
So, it stretches the (right atrium) chamber
This increase the SA node firing rate
…. So, HR increases

Question 6

what happens to VR at rest

Answer 6

VR is sufficient to maintain SV and Q to meet demand for O2

Question 7

what are pocket valves

Answer 7

Pocket Valves prevent backflow of blood and direct it towards the heart

Question 8

what are the 5 mechanisms assisting venous return

Answer 8

Pocket Valves
Muscle Pump
Respiratory Pump
Smooth Muscle
Gravity

Question 9

what are muscle pumps

Answer 9

Veins are situated between skeletal muscles.

When the muscles contract, this helps to push or squeeze blood back to the heart.

Question 10

what are respiratory pumps

Answer 10

During exercise, breathing becomes deeper and faster.

This causes pressure changes in the thorax and abdomen, squeezing large veins and thus blood back to the heart.

Question 11

what are smooth muscles

Answer 11

Contraction and relaxation of smooth muscle in the middle layer of the vein walls helps push the blood towards the heart.

Question 12

how does gravity aid VR

Answer 12

Blood from the upper body is aided by gravity

Question 13

what is blood pooling

Answer 13

If there isn’t enough pressure, the blood will sit in the pocket valves of the veins.

Question 14

how does VR effect performance

Answer 14

Increase in SV/ Q which will increase O2 to the working muscles resulting in increased aerobic capacity

This will decrease speed of fatigue, delay OBLA and help oxidise lactic acid.

Good VR will speed up recovery and allow performers to work for longer.

Question 16

how can we help these mechanisms affect exercise

Answer 16

An active cool-down helps to get O2 and nutrients to the muscles whilst capillaries are still dilated via