Venous Return Flashcards
What is the formula for calulating venous return?
VR=CO= (MABP-RAP)/SVR
What is the formula for calulating the effective pressure gradient for venous return?
Effective Pressure Gradient= Pressure in veins-RAP
What is the relationship between Pressure gradient and venous return?
Directly proportional
True or false: When excerising blood is stored in veins.
FALSE
How can compliance be calculated?
compliance= change in volume/ change in pressure
What is the effect of introducing saline on venous return?
Increased venous return?
What effect does a decrease in compliance have on venous pressure? On venous return
Venous pressure and return increase
How do flaccid veins decrease compliance?
Vascular smooth muscle contraction
How is SNS-stimulated vascular smooth muscle contraction mediated?
NE is released and binds to alpha-receptor in vascular SM, increasing Ca2+ concentration
What is the effect of SNS stimulation on venous return?
Increases
What factors other than compliance influence venous return?
Skeletal muscle contraction, venous valves, thoracoabdominal pump
What is the effect of skeletal muscle contraction of venous return?
When SKM contracts, it compresses the veins, propelling blood back to the heart
What is the result in incompetant veins?
Blood backflow leading to varicose veins
What is the thoracoabdominal pump?
During inspiration the diaphragm contracts and lowers, causing a decrease in thoracic pressure and increase in abdominal pressure, which increases the pressure gradient and drives VR toward the thorax
