KINE 1P90 Lecture Notes - Lecture 9: Extracellular Fluid, Metarteriole, Endothelium

• School: Brock University
• Department: Physical Education and Kinesiology
• Course: KINE 1P90
• Professor: Klentrou Panagiota

Document Summary

Capillaries are ideally suited to enhance diffusion and exchange materials between the blood and the tissues of the body. Diffusing molecules have a short distance to travel between the blood and the surrounding tissues. Capillary walls are thin (a single layer of endothelial cells) The lumen of each capillary is very narrow (the blood cells must squeeze through in single file) Extensive capillary branching (no cell is farther than 0. 01cm from a capillary) Enormous total surface area, but only holding 5% of the total blood volume at any given time. Blood travels very slowly through the capillary network because it needs time for a change. The diffusion of across capillary walls depends on the permeability of the wall to any given material. This permeability will differ from organ to organ, and may be enhanced (ex. Pores form between adjacent endothelial cells, and allow the passage of small water- soluble substances.