BISC 101 Lecture Notes - Lecture 20: Malpighian Tubule System, Nephridium, Rotifer
14 Mar 2016
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Document Summary
Water and ions move by diffusion and osmosis. In aquatic animals specialised epithelial cells (chloride cells) pump ions in our out depending on the habitat (active transport) Terrestrial animals water balance is problem due to water loss. Osmoregulation: balances the uptake and loss of water and solutes (homeostasis of osmolarity of body fluids) Excretion: removal of excess solutes, nitrogenous metabolites and other wastes (involves water) Diversity of specialised excretory systems have evolved all variations on a linear, tubular theme (which allows for specialisation) Nephridia (flatworms), malpighian tubules (insects), kidney nephron. Duration of urination does not change with body size (vertebrates) Animals internal osmotic and solute (ion) can be regulated or it can conform to the environment. Body fluids/fish are hypoosmotic in seawater (300 <<< 1000 mosm/l) Continuously lose water via osmosis (drink large amounts of water- creates problem of accumulation of ions (from water and in food))
