VENOUS RETURN Flashcards
what is venous return?
the return of blood to the heart, through the venules and veins back to the right atrium, largely against gravity
what maintains venous return at rest?
blood pressure and the structure of the veins
what happens to venous return during exercise?
what maintains venous return at rest?
blood pressure and the structure of the veins
what happens to venous return during exercise?
a greater demand of oxygenated blood requires a greater venous return to increase stroke volume and therefore cardiac output (Starlings law)
which additional mechanisms help maximise venous return during exercise?
- pocket valves
- smooth muscle
- gravity
- muscle pump
- respiratory pump
pocket valves
one way valves located in the veins which prevent the backflow of blood
smooth muscle
the layer of smooth muscle in the vein wall venoconstricts and/or venodilates to change the degree of venomotor tone which aids the movement of blood
How does gravity effect this?
blood from the upper body, above the heart, is helped to return by gravity
what is the function of a muscle pump?
during exercise, skeletal muscles contract compressing the veins located between them, squeezing the blood back to the heart
What is the function of a respiratory pump?
during inspiration and expiration, a pressure difference between the thoracic and abdominal cavity is created, squeezing the blood back to the heart. as exercise increases respiratory rate, the respiratory pump is maximised
what can insufficient pressure to return the blood back to the heart after exercise cause?
dizziness, light-headedness and blood pooling
What is blood pooling?
blood accumulating in the veins due to lack of venous return
how do we maintain venous return during recovery?
do an active cooldown
what does an active cool down do to assist venous return?
maintains the respiratory and muscle pumps retuning blood to the heart
