BIOL 204 Lecture Notes - Lecture 14: Fibrin, Osmoregulation, Countercurrent Exchange
Document Summary
The composition & functions of blood: blood plasma: holds the blood cells in suspension, the extracellular matrix of blood cells (makes up 55% of the blood) Plasma proteins: purpose is osmotic balance, ph buffering, defense (antibodies), lipid transport, clotting (fibrinogen: cellular elements of blood (45%): Leukocytes: white blood cells (defense and immunity) Erythrocytes: red blood cells (transport of o2 and co2) Human erythrocytes are biconcave discs (because high sa:volume) No mitochondria (atp is generated through anaerobic metabolism) Contain hemoglobin (iron-rich protein that binds to o2: bone marrow: contains stem cells that form blood cells, blood clotting: Platelets stick to collagen fibers in vessel"s connective tissue. Plug is reinforced by a fibrin clot, forming a fibrin clot: prothrombin converts to thrombin, thrombin catalyzed fibrinogen to fibrin. Gas exchange structures & systems: gills: outfoldings of the body wall (high sa:volume), lots of capillaries, ventilation to increase gradients.
