8. Osmoregulatin and Excretion post

8 Osmoregulatin - Chapter 44 Osmoregulation and Excretion Johannes Vermeer"Woman Holding a Balance c 1664 Homeostasis The ability to maintain a

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Johannes Vermeer "Woman Holding a  Balance" c. 1664 Chapter 44 Osmoregulation and Excretion
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Homeostasis The ability to maintain a  relatively narrow range  of internal conditions Conditions that need to  be regulated Thermoregulation Osmoregulation Nitrogenous waste  (excretion)
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Osmosis, Solutes, and Osmolarity Water enters the cell by osmosis Determined by osmolarity Two solutions separated by semi-permeable  membrane with different solute concentrations Total solute concentration Molarity (moles/L) mosm/L in biological systems 300 mosm/L for human 1000 mosm/L for seawater Isoosmotic, hyperosmotic, hypoosmotic
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Regulators and Conformers Osmoconformers Isoosmotic to surroundings Marine animals Osmoregulators Internal osmolarity is different from external environment Important to allow animals to live in different environments Energy costs Types Hypoosmotic – discharge excess water Hyperosmotic – take in water
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Osmoregulators at Sea Problem: External  environment is hyperosmotic Water loss (dehydration) Salt accumulation Compensation Osteichthyes Drink water Active transport of salts out of  gills Transport epithelium Very little urine is formed Chondrichthyes Increase osmolarity Urea Trimethylamine oxide (TMAO) Salts diffuse in b/c of high  osmolarity but removed by  kidney, rectal gland or lost in  feces No drinking necessary
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Osmoregulators in Freshwater Problem: External  environment is  hypoosmotic Gaining water by  osmosis Losing salts by diffusion Compensation Some inverts ( Amoeba   and  Paramecium ) have  contractile vacuoles that  pump out excess water Vertebrates Avoid drinking water Produce large volumes  of urine Active transport of salts  back into body Gills (Fish) Skin (amphibians)
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Osmoregulators on Land Problem: External  environment is dry Water loss Respiration Urine Feces Across the skin
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This note was uploaded on 04/17/2008 for the course BIOL 112 taught by Professor Maze during the Spring '08 term at Lander.

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8 Osmoregulatin - Chapter 44 Osmoregulation and Excretion Johannes Vermeer"Woman Holding a Balance c 1664 Homeostasis The ability to maintain a

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