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Chapter 44

Chapter 44. Osmoregulation. Osmoregulation. Balancing the release and uptake of water and solutes an animal′s ability to regulate the chemical composition of its body fluids depends on balancing the uptake and loss of water and solutes

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Chapter 44

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  1. Chapter 44 Osmoregulation

  2. Osmoregulation • Balancing the release and uptake of water and solutes • an animal′s ability to regulate the chemical composition of its body fluids depends on balancing the uptake and loss of water and solutes • based largely on controlled movement of solutes between internal fluids and the external environment • process also regulates the movement of water, which follows solutes by osmosis

  3. Transport Epithelium • layer or layers of specialized epithelial cells that regulate solute movements • move specific solutes in controlled amounts in specific directions • transport epithelia are arranged into complex tubular networks with extensive surface areas

  4. Nitrogenous Wastes • Proteins and nucleic acids are broken apart for energy or converted to carbohydrates or fats, enzymes remove nitrogen in the form of ammonia (NH3)

  5. Excretory Process • Filtration • Selective Reabsorption • Secretion • Excretion

  6. Mammalian Excretory System

  7. Functional Units of the Mammalian Kidney • Nephron and associated blood vessels

  8. Nephron Function • Proximal tubule - reabsorption of most of the NaCl (salt) and water from the huge initial filtrate volume • pH regulation

  9. Nephron Function • Descending limb of the loop of Henle - reabsorption of water – highly permeable to water, lower permeability to salts • Interstitial fluid bathing the tubule hyperosmotic to the filtrate • Filtrate concentration increases as water moves into interstitial fluid

  10. Nephron Function • Ascending limb of the loop of Henle – 2 specialized regions: thin segment and thick segment • thin segment highly permeable to NaCl but not water. NaCl diffuses into inner medula • Thick segment actively transports more NaCl into interstitial fluid

  11. Nephron Function • Distal tubule – regulation of K+ and NaCl by varying secretion/reabsorption • Regulation of pH

  12. Nephron Function • Collecting Duct- active transport of NaCl • Reabsorption of water under hormonal control (antidiuretic hormone from hypothalmus) to maintain homeostasis

  13. Hormonal Control of Kidney Function ADH – osmolarity RAAS and ANF – Blood volume

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