BIOL 1F25 Study Guide - Midterm Guide: Cranial Cavity, Axillary Artery, Ascending Aorta

• School: Brock University
• Department: Biological Sciences
• Course: BIOL 1F25
• Professor: Gaynor Spencer

Document Summary

The blood vessels (arteries, arterioles, capillaries, venules, and veins) form a closed tube that carries blood away from the heart, to the cells, and back again. Arteries are strong, elastic vessels adapted for carrying high-pressure blood: arteries become smaller as they divide and give rise to arterioles. The wall of an artery consists of an endothelium, tunica media (smooth muscle), and tunica externa (connective tissue). Arteries are capable of vasoconstriction as directed by the sympathetic impulses; when impulses are inhibited, vasodilation results. Capillaries: capillaries are the smallest vessels, consisting only of a layer of endothelium through which substances are exchanged with tissue cells. Capillary permeability varies from one tissue to the next, generally with more permeability in the liver, intestines, and certain glands, and less in muscle and considerably less in the brain (blood-brain barrier). The pattern of capillary density also varies from one body part to the next. a.