Final answer:
Capillary exchange mechanisms involve diffusion, facilitated diffusion, endocytosis, exocytosis, and osmosis to allow the exchange of different substances between the capillary blood and surrounding tissues.
Step-by-step explanation:
In capillary exchange, various substances like glucose, plasma proteins, large lipid insoluble substances, water, and oxygen are exchanged between the capillary blood and the surrounding tissues. Glucose is a small molecule that can diffuse directly through the endothelial cells of the capillary wall. It can also move through specific channels in the membrane by facilitated diffusion.
Plasma proteins are large molecules that cannot diffuse easily. They are carried across the cell membrane by endocytosis and exocytosis. Some plasma proteins can move through the gaps in sinusoids. Since these substances are large and lipid insoluble, they cannot easily diffuse through the capillary wall. However, they can pass through pores of fenestrated capillaries or move through intercellular clefts.
Water moves through capillaries by osmosis. It can also move through the capillary wall, which is permeable to water. Oxygen is a small, lipid-soluble molecule that can diffuse directly through the endothelial cells of the capillary wall. In summary, capillary exchange mechanisms involve diffusion, facilitated diffusion, endocytosis, exocytosis, and osmosis to allow the exchange of different substances between the capillary blood and surrounding tissues.