BIO202H5 Study Guide - Midterm Guide: Osmosis, Macroevolution, Carbonic Anhydrase

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Counter current flow: blood passes in opposite direction to the water. If blood and water flowed in the same direction (con-current) Past central point is equilibrium (exchange no longer occurs) Blood and water flow in opposite direction (countercurrent) The most oxygen-rich water comes into contact with the most oxygen-rich blood. As water passes along gill lamellae, oxygen units decrease (favorable exchange) b/c blood is flowing in opposite direction, the oxygen-poor blood encounters oxygen poor water. Maintains favourable exchange by entire surface oxygen moving from water into the blood. Gill filaments & lamellae - provide large surface area. If not in water, collapse and have less surface area. ---has gill filaments attached to it (have rich blood supply) ------have lamella (serve to increase surface area) increase surface area. Water flows over filaments of gills, out as mouth closes and operculum opens. Oxygen rich water moving across the gills.