BIO 215 Lecture Notes - Lecture 6: Theca Interna, Vascular Smooth Muscle, Tunica Media
Document Summary
Closed system of tubes that carries blood throughout the body. Arteries carry blood from the heart to tissues. Capillaries are thin rough to allow exchange of gases, nutrients and waste products. Venules merge to form veins and bring blood back to the heart. Tunica interna (intima: simple squamous epithelium known as endothelium, basement membrane. Tunica media: circular smooth muscle and elastic fibers, external elastic lamina. Tunica externa: elastic and collagen fibers. Endothelium continuous with endocardial lining of heart. Active role in vessel-related activities: tunica media, tunica externa. Vaso vasorum small vessels which supply the vessel itself. Distribute blood to various parts of the body. Sympathetic innervation: vascular smooth muscle is innervated by sympathetic nervous system only increase in stimulation causes muscle contraction or vasoconstriction, decreases diameter of vessel injury to artery or arteriole causes muscle contraction reducing blood loss (vasospasm)
