Venous Physiology (Lecture 4) Flashcards
What is Capacitance?
The volume of a blood that a vessel can hold at a given pressure
What is the equation for Hydrostatic Pressure?
p x g x h
p = density of blood
g = acceleration due to gravity
h = height of the column of blood
When supine, what is the hydrostatic pressure?
Negligible
When lying down, pressure throughout the vascular system is what in comparison to the dynamic pressure? Higher, lower, the same?
The same (equal)
How much hydrostatic pressure does a person exhibit on the ankles when standing?
102 mmHg
What is the change to ability to exchange nutrients across the capillary bed when supine vs. standing?
There is none
During exercise, what does the pressure in the veins fall below?
20 mmHg
During exercise, does the pressure gradient across the capillaries rise or fal?
Rise, it increases
What is transmural pressure?
The pressure within the vein, tissue pressure
At low transmural pressure, what shape will the vein assume?
Dumbbell
At an equal transmural pressure, what shape is the vein?
Elliptical
At a high transmural pressure, what shape will the vein become?
Circular
What is osmotic pressure?
The pressure exerted by fluid when there is a difference in the concentrations of solutes across the capillary endothelium
Does standing increase capillary pressure?
Yes, forces fluid out of capillaries into the interstitial tissue
What happens to the diaphragm and chest pressure during inspiration?
It descends, which decreases pressure in the chest cavity and pulls blood into the pulmonary vascular bed
