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Unformatted text preview: Lecture 9 Circulation I. Anatomy A. Arterioles Contains lots of smooth muscle built into walls Causes vasoconstriction/dilation Distribution vessels take blood from heart to tissues very quickly B. Capillary bed Exchange with tissue takes place High density Slow flow velocity 0.07 cm/sec Exchange vessels: slow velocity to allow for time for exchange with tissue C. Capillaries designed to allow good exchange Diameter: arterial - ~5; venus - ~9 Walls: 1 RBC is 8 , fold itself up and squeezes through capillary red cell membrane makes direct contact with capillary membrane Dont have a lot of plasma around cell. Single endothelial cell cells that contact the blood No smooth muscle (no constriction/dilation) Tight junction II. Transport across capillary wall A. Diffusion ways to get through 1. Across cell membranes Small, lipid soluble O 2 , CO 2 , steroid hormones 2. Tight junctions (has water, water soluble can go through) Ex. Salts, glucose, etc B. Large molecules 1. vesicle transport 2. fenestrations (pores) kidney intestines liver bone marrow C. Filtration Fluid movement Carries small, water soluble stuff 1. Forces out a. Capillary Hydrostatic Pressure (P c ) (capillary forcing fluid out) Arterial side ~30 mmHg Venous side ~15 mmHg b. Interstitial Tissue Oncotic pressure ( i )...
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- Winter '08