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Unformatted text preview: Chapter Learning Objectives Chapter 44 Concept 44.1: Osmoregulation balances the uptake and loss of water and solutes • Define osmoregulation and excretion o Osmoregulation The general process by which animals control solute concentrations and balance water gain and loss o Excretion The process that rids the body of nitrogenous metabolites and other waste products • Define osmolarity and distinguish among isoosmotic, hyperosmotic, and hypoosmotic solutions o Osmolarity Solute concentration expressed as molarity o Isoosmotic When two solutions separated by a selectively permeable membrane have the same osmolarity o Hyperosmotic When two solutions differ in osmolarity, the one with the greater concentration of solutes o Hypoosmotic When two solutions differ in osmolarity, the more dilute solution • Distinguish between osmoregulators and osmoconformers. Explain why osmoregulation has an energy cost o Osmoregulators An animal that controls its internal osmolarity independent of the external environment o Osmoconformer An animal that is isotonic with its environment • Distinguish between stenohaline and euryhaline animals o Stenohaline Cannot tolerate substantial changes in external osmolarity o Euryhaline Can tolerate wide fluctuations in external osmolarity • Discuss osmoregulatory strategies of marine animals o Balance their water loss by drinking large amounts of seawater Use gills and kidneys to rid themselves of salts o Have an internal salt concentration much less than that of seawater so salt ends to diffuse into their bodies from the water Especially across their gills o Sharks use a different strategy Live in salt water, but are Hyperosmotic to it They retain high concentrations of urea in body fluids Also high concentrations of TMAO • Protects proteins from urea • Explain how osmoregulatory problems of freshwater animals differ from those of marine animals o The body fluids of freshwater animals must be hyperosmotic because animals cells cannot tolerate salt concentrations as low as those of lake or river water o Having internal fluids with an osmolarity higher than that of their surroundings, freshwater animals face the problem of gaining water by osmosis and losing salts by diffusion o Solve the problem of water balance by drinking almost no water and excreting large amounts of very dilute urine At the same time, salts lost by diffusion and in urine are replenished by eating Salt can also be replenished by uptake across the gills • Describe some adaptations that reduce water loss in terrestrial animals...
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This note was uploaded on 04/03/2012 for the course BIOL 1202 taught by Professor Gregg during the Spring '08 term at LSU.
- Spring '08