Question

Explain why all tissue cells have to be very vlose to a capillary?

Answer 1

Capillaries are the smallest of the vessels, across which all exchanges are made with surrounding cells and tissues. Oxygen and nutrients, such as glucose, diffuse out of capillaries into the interstitial fluid that surrounds cells. Wastes such as CO₂ diffuse into the capillary. Capillaries rejoin to form venules, which further merge to form small veins that leave the organs. In some body parts, blood passes from one capillary into another through the portal vein, constitutes a portal system. There are portal systems associated with the pituitary gland and the liver.