BIO 203 Lecture Notes - Lecture 19: Aquaporin, Coelom, Tonicity
8 Dec 2017
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Solutions to water loss: limit loss, waterproof where possible, bury gas exchange surfaces, minimize excretory volume, water content. Strong tendency to lose water to air. Desert adapted mammal strongly limits amount of excretion. Typical terrestrial animal most lost through excretion some lost through evaporation (mostly lungs, some sweat) Freshwater: tends to gain water, tends to lose salt. Marine: tends to lose water, except osmoconformers, tends to gain salt, except ionoconformers. Terrestrial: net loss/ gain of salt depends on diet, tends to lose water. Epithelia-sheet of tissues that cover the organism, separate compartments, separate out from in. Functions: protect, compartmentalize, transport: control fluid composition. Side of tissue: blood side: serosa (serum, lumen/ outside: mucosa. Types: absorptive, moves substrate from mucosa to serosa, absorb into blood, na inside is low. Apical membrane has high na+ influx: na channels: high pna. Chloride follow passively: through paracellular pathway controlled by tight junction permeability, through transcellular pathway controlled by membrane transport processes.
