Capillary Beds Flashcards
(13 cards)
Function of capillaries and what it takes place between
They are the links between arterial and venous systems that exchange gases, nutrients, and hormones. This takes place between the interstitial fluid bathing each body cell.
Structure of capillaries
They’re 1 cell thick, and have lumen and tunic intima. Diameter of 8um.
How the capillaries work
Thin cell wall permits rapid exchange of material.
Red blood cells must line up one by one to get through.
O2 and CO2 diffuse through the capillary membrane.
How do nutrients and hormones get through capillaries?
They’re dissolved in the plasma and force filtered out by arterial blood pressure.
They then diffuse through the interstitial blood to individual cells.
What are the two sides of the capillary bed?
The venous side and the arterial side.
What happens in the venous side of the capillary bed?
Water and wastes are recovered and carried away.
How are capillaries arranged according to distance?
They’re arranged so that no cell in the body is more than a few cells away.
What are capillary beds?
Capillary beds are dense networks of capillaries that are regulated to match the activity of the tissue.
Example of how capillary beds regulate to match the activity of tissue?
The capillary beds of the digestive system are open when digestion is taking place so that nutrients can be better absorbed.
Metarteriole?
A capillary that moves blood directly from arterials to venous if the capillary bed is closed.
What are precapillary sphincter muscles?
They’re rings of muscle where capillaries branch from arterioles.
What do precapillary sphincter muscles do?
They open or close the capillary bed by relaxing or contracting.
What does an increase in CO2 cause?
Relaxation
