Lecture 7 Microcirculation Flashcards
What is delayed compliance of veins?
The time taken to readjust to changes in blood volume
What is the effect of external pressure on venous return?
Any compression prevents flow from occurring in large peripheral veins, leads to swelling especially in legs
What is the venous pump?
The moving and squeezing of muscles in one direction due to valves, particularly in legs
What are varicose veins?
Faulty venous valves, preventing blood from flowing in one direction
What is the function of the microcirculation?
Waste removal and nutrient delivery
Rank key tissues in terms of their permeability
(lowest - LOW Kf) Brain, GI system, liver, bone marrow (highest - HIGH Kf)
What are the two main components in interstitial fluid?
Collagen fibers and proteoglycans
What are proteoglycans?
A family of proteins with lots of sulfated sugar chains for retention, do lots of stuff including store growth factors, alter signaling cascades, water sponge etc
What two forces act in balance to determine net fluid movement across capillaries?
- Hydrostatic pressure, from inside and outside the capillary membrane
- Osmotic pressure, dependent on protein concentrations
Name the two inward forces acting on capillary membranes
Interstitial hydrostatic fluid pressure, inward plasma colloid osmotic pressure
Name the two outward forces acting on capillary membranes
Capillary hydrostatic pressure and interstitial fluid colloid osmotic pressure
What does interstitial fluid hydrostatic pressure do?
Promotes filtration by causing osmosis of fluid outwards
What does plasma colloid osmotic pressure do?
Opposes filtration because of albumin and other ions
What does interstitial fluid colloid osmotic pressure do?
Promotes filtration because there are ions bound to proteoglycan in interstitial fluid
If net filtration pressure is positive…
Liquid moves out of the capillary
