L10_Ion and Water Balance_pt1

L10_Ion and Water Balance_pt1 - Ion and Water Balance - pt1...

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Unformatted text preview: Ion and Water Balance - pt1 Overview  Environment has several different meanings  External world for the whole animal  Extracellular fluid for a cell  Cytoplasm for intracellular enzymes Overview (Fig 10.1)  Animals use different combinations of tissues to control ion and water balance in various internal and external environments (in mammals, usually kidneys, simple creatures can use skin, gills) Overview  Three homeostatic processes € Osmotic regulation ( Osmotic pressure of body fluids  Ionic regulation y Concentrations of specific ions  Nitrogen excretion y Excretion of end-products of protein metabolism Ionic and Osmotic Challenges  Marine environments  Animals tend to gain salts and lose water  Freshwater environments  Animals tend to lose salt and gain water  Terrestrial environments  Animals tend to lose water  Many animals move between environments and must be able to alter their homeostatic mechanisms Ionic Regulation Strategies to meet ionic challenges Ionoconformer  Exert little control over ion profile within the extracellular space  Exclusively found in marine animals  For example, many invertebrates Ionoregulator  Control ion profile of extracellular space  For example, most vertebrates Osmotic Regulation  Strategies to meet osmotic challenges Osmoconformer  Internal and external osmolarity similar  For example, marine invertebrates Osmoregulator  Osmolarity constant regardless of external environment  For example, most vertebrates Ionic and Osmotic Regulation  Ability to cope with external salinities Stenohaline  Can tolerate only narrow range Euryhaline  Can tolerate wide range Sources of Water and Solutes  Water Dietary Water  Water preformed in plant and animal tissue ˜ Metabolic Water  Water generated as result of oxidative phosphorylation (of glucose)  Drinking Classification of Solutes (Fig 10.3) Distinguished by their effects on macromolecules...
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L10_Ion and Water Balance_pt1 - Ion and Water Balance - pt1...

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