BSI 2 Lecture 19-20: Capillary Fluid Exchange Flashcards
What four factors drive fluid exchange across the capillary wall?
1) Capillary hydrostatic pressure
2) Interstitial fluid colloid osmotic pressure
3) Interstitial fluid hydrostatic pressure
4) Capillary colloid osmotic pressure
What does capillary hydrostatic pressure tend to do?
Drive fluid out through the capillary membrane
What does interstitial fluid colloid osmotic pressure do?
Causes osmosis out of the capillary
What is the hydrostatic pressure of interstitial fluid?
Normally close to zero
What does capillary colloid osmotic pressure cause?
Osmosis into the capillary
At the arterial side of capillaries, _______ is favored.
net filtration
At the venous side of capillaries, _______ is favored.
net reabsorption
What is the primary difference between each end of the capillary?
There is a 15-25 mmHg difference in capillary hydrostatic pressure between each end
What causes edema to occur?
the rate of fluid that enters the interstitium is greater than what the lymphatic system can remove
What can every cause of edema be related to?
1) Increased capillary hydrostatic pressure
2) Increased capillary permeability
3) Decreased plasma oncotic pressure
4) Lymphatic obstruction
How much fluid from the capillary is put back into circulation by the lymphatic system?
2-3 L/day
What is the only way to remove proteins from the interstitial space?
Lymphatic system
Why is it important to keep proteins in circulation and out of the interstitial fluid?
That’s what keeps the interstitial fluid colloid osmotic pressure low
What happens to lymph flow as interstitial fluid pressure rises?
It increases
