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Osmoregulation & Excretion

Osmoregulation & Excretion. Chapter 44. To Live on Earth. Physiological systems of animals operate in a fluid environment Relative concentrations of water and solutes MUST be maintained within fairly narrow limits. Osmoregulation & Excretion.

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Osmoregulation & Excretion

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  1. Osmoregulation & Excretion Chapter 44

  2. To Live on Earth • Physiological systems of animals operate in a fluid environment • Relative concentrations of water and solutes MUST be maintained within fairly narrow limits

  3. Osmoregulation & Excretion • Osmoregulation regulates solute concentration and balances the gain and loss of water • Excretion gets rids of metabolic wastes • HOMEOSTASIS

  4. Marine Animals • Osmoconformers • Change with surroundings • Osmoregulators • Regulate through osmosis • Ex: Galapagos marine iguanas • Video

  5. Marine Fish • Osmoregulators • Environment is hypertonic to their cells • Water is constantly consumed, urination occurs rarely, excess salt is secreted through gills

  6. Freshwater Animals • Environment is hypotonic to their cells • Rarely drink, constantly urinate, absorb salts through their gills

  7. Animals in Temporary Waters • Lose almost all their body water and survive in a dormant state • Anhydrobiosis

  8. Land Animals • Manage water budgets by drinking and eating moist foods and using metabolic water

  9. Nitrogenous Waste • Humans • When proteins and nucleic acids are broken down, ammonia (NH3) is released • Convert this into urea in the liver • Far less toxic than ammonia

  10. Diversity of Excretory Systems • Contractile vacuoles (Protista) • Collect and expel water • Protonephridia with flame cells (Platyhelminthes) • Cells spread throughout a tube system that filter fluids leaving the animal

  11. Metanephridia (Annelida) • Tubes throughout the worm that filter out body fluid • Malpighian tubules (insects) • Filters materials from the gut

  12. Kidneys (vertebrates) • Made of filtering tubes called nephrons • Supplied with blood by renal artery, drained by renal vein • Urine exits each kidney through a duct called the ureter • Both ureters drain into a common urinary bladder

  13. Nephron Structure • Bowman’s capsule • Blood enters via renal artery • Convoluted tubule • Blood passes through here and is surrounded by capillaries • Collecting duct • Drains waste from multiple nephrons into ureter

  14. Nephron Function • Filtration • Pressure forces water and solutes (filtrate) from capillaries into Bowman’s capsule and flows into convoluted tubule • Reabsorption • Water and salt are removed and it moves down through the renal pelvis as concentrated urine • Secretion • Additional materials from body fluids join filtrate and are secreted into the convoluted tubule • Excretion • Removing the filtrate from the system

  15. Hormone Involvement • Renin-Angiotensin-Aldosterone system (RAAS) • Juxtaglomerular apparatus (JGA) • Specialized tissue near afferent arterioles – responds to decreased pressure or volume by releasing enzyme rennin into blood • Renin converts inactive angiotensin to activate angiotensin II (RAAS) • Angiotensin II increases blood pressure by: • Causing arteriole constriction • Stimulating proximal tubules to absorb more NaCl and water • Signaling adrenal glands to release aldosterone (stimulates Na+ absorption, water follows)

  16. Antidiuretic Hormone (ADH) • Enhances fluid retention by increasing water permeability of distal tubules and collecting ducts • Produced in hypothalamus, released from pituitary gland • ADH release is triggered when osmoreceptor cells in hypothalamus detect increased blood osmolarity due to excessive water loss • Alcohol and caffeine inhibit ADH release causing dehydration

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