BIOB34H3 Study Guide - Final Guide: Dentin, Byrsonima Crassifolia, Facilitated Diffusion
15 Dec 2012
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Vol and comp must be maintained within narrow limits. Comp tends to change towards equilib with the enviro. Organism must control changes in comp of bodily fluid. Osmotic [ ] largely due to organic solutes. Rectal gland - excretes fluid with high [ nacal ] Water used in urine formation and rectal gland secretion. Ions tend to be lost from the gills. Internal : lumen of digestive and excretory systems. Have physiological fctns in respiration, digestion and ion and water regulation. Ways of losing : evaporation (body surface, resp surface) Rate of water loss determined by transfer of water to surrounding air. Rate of evaporation altered by changing membrane permeability. Animals change in flux of water across body surface by mediating permeability of the integu- ment. Cover external surfaces with layer of hydrophobic molecules. All tetrapods depend on keratinized stratum corneum to minimize dessication. Is the thickend external layer or modified epithelium found in mammals.
