CAPS 390 Lecture 20: Lect_20_Circulatory_Summary
18 Nov 2015
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Lecture 20 circulatory system, oct 20, 2014 (dr. roskelley) Lymphatic system (see lect 21 for details) Cardiovascular system: heart/pump, two circuits : i) pulmonary ii) systemic. Outer wall consists of 3 layers (tunics) ** tunics vary in tissue composition and structure depending on vessel type and location. 1. tunica intima (ti; inner layer) Simple squamous to cuboidal epithelium (ie. the inner lining "endothelium") Basement membrane, and lamina propria (subendothelial connective tissue) Pericytes may be present, especially capillaries. Internal elastic lamina is a thin layer of elastic c. t. 2. tunica media (tm; middle layer) ** varies the most depending on blood vessel type. Variable amount and type of connective tissue (collagenous and elastic tissue) Concentrically/circularly arranged smooth muscle cells (contractile portions of cells wrap themselves around the vessels horizontally) Concentrically/circularly arranged elastic fibers especially abundant in big arteries. 3. tunica adventitia (ta; outer layer) May contain small blood vessels ("vasa vasorum") that supply walls of large vessels.
