BISC 101 Chapter Notes -Malpighian Tubule System, Osmoregulation, Nephridium
27 May 2014
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Document Summary
Osmoregulation balances the uptake and loss of water and solute =homeostasis. Excretion the removal of excess solutes, nitrogenous metabolites and other wastes. Excretion of nitrogenous wastes impacts water balance; forms of nitrogenous wastes vary with phylogeny and habitat. Both involve diffusion, osmosis, active transport across transport epithilia. A diversity of excretory systems is all variations on a linear, tubular theme nephridia, malpighian tubules, kidneys nephron. An animal"s environment dictates the osmoregulatory and ionoregulatory. Hypo-osmoitc in sea water and hyper-osmotic in freshwater. Water gain 1) ingested in food/ drink 2) metabolic water. Water loss 1) feces 2) urine 3) evaporation. Terrestrial animals- main regulatory problem is dehydration key adaptations to reduce water loss. Terrestrial life without water anhydrobiosis (a dormant or survival state) 1)a disaccharides replaces water to protect cells and membranes 2) application for storage of human tissues without freezing. Marine birds have plenty of water but too much salt another countercurrent exchange system.
