BMS 420 Lecture Notes - Choroid Plexus, Mass Diffusivity, Vascular Smooth Muscle
Document Summary
Vasomotion waxing and waning of tone of upstream vascular smooth muscle cells. Density of capillaries (vascularization) obviously important for exchange lung has capillary area of 3,500 cm2/g while muscle is about 100 cm2/g; tendon low density. Degree of patency varies 100% heart to 20 30% in skeletal muscle and intestines at rest. Arterioles: 5 25 m; continuous vsm; innervated (sympathetic); controls capillary q. Precapillary sphincter: single band of vsm; usually not innervated; controls capillary q. True capillaries: 2 -5 m; primarily endothelial cells; thin walled (200 300 nm); not innervated. Occurs primarily in capillaries but also in metarterioles (oxygen) and venules (protein) Fenestrated largish pores between cells (kidney, e. g. ) Pinocytotic vesicles allow higher weight molecules to move out of blood. 4 types of transport: diffusion, bulk flow, vesicular transport, active transport. Single layer of endothelial cells (. 2 m thick) Muscle, skin, lung, connective tissue, and nervous system. Hydrophilic solutes pass via clefts water, ions, small organic solutes.
