Function of Excretion - fresh: < 0.5 ppt body is...

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Function of Excretion Evolution of Excretion: Detoxification and Water Balance 1. Active Transport Active Secretion Primitive Animals: Eating by Phagocytosis NH4 production: toxic (pH) evolve some selective excretion mechanisms of passing toxins without loosing needed molecules 2. Water Balance SW > FW > land cells must be isotonic with surrounding Sea Water: First Animals "blood" = surrounds re. salt conc. >> isosmotic (SW = 35 ppt, 3.5% salt, ~1 Osmol Movement into fresher water SW: 35 ppt brackish: 5-30 ppt
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Unformatted text preview: fresh: < 0.5 ppt body is saltier than surrounds water moves in by osmosis water must be pumped out NH4 OK metabolite: diluted by copious H2O Terrestrialization: Water must be conserved NH4 problem w/out dilution Mechanisms evolve to conserve water resorb water from feces and urine urea and uric acid instead of NH4 less toxic, less water needed Concentration of urine above body salinity. ONLY mammals and birds Most Animals CAN NOT concentrate their urine more than their body salinity Loops of Henle...
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Function of Excretion - fresh: < 0.5 ppt body is...

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