Venous Return Flashcards
What is venous return?
The return of blood back to the right atria through the veins, usually against gravity but not always
In what way is stroke volume during exercise affected by venous return?
- Increased venous return during exercise
- The Frank-Starling Mechanism
How does an increase venous return during exercise affect stroke volume?
More blood returning to the heart and filling the ventricles due to the muscular pump means there is more blood to be expelled
How does the Frank-Starling Mechanism affect stroke volume?
There is an increased stretch of the ventricular walls and therefore, an increased force of contraction
What are the 5 mechanisms of venous return?
- Pocket Valves
- Smooth Muscle
- Gravity
- Muscle pump
- Respiratory pump
What are pocket valves?
One way valves in the veins that prevent the back flow of blood
What is smooth muscle in venous return?
A layer of smooth muscle in the veins which venoconstricts to create a venomotor tone aiding the movement of blood
How does gravity help venous return?
Blood from above the heart is pulled down by gravity
What is the muscle pump in venous return?
Skeletal muscles contract and compress the veins between them and squeeze blood back to the heart
What is the respiratory pump in venous return?
A pressure difference in the thoracic cavity and abdominal cavity squeezes blood back to the heart
What happens to venous return in recovery?
Cardiac output is high but there is not enough pressure for venous return. This leads to ‘blood pooling’
What is ‘blood pooling’?
Accumulation of blood in the veins due to gravitational pull and lack of venous return
How is ‘blood pooling’ prevented?
A warm down, ‘active recovery’, maintains venous return during rest and prevents ‘blood pooling’
