Osmoregulation

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• Osmoregulation
• The active regulation of osmotic pressure of body
  fluids so that homeostasis is maintained
• Excretory systems
• Help maintain homeostasis by regulating the
  concentration of body fluids

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• Principal waste products of animal metabolism
• Water
• Carbon dioxide
• Nitrogenous wastes
• Ammonia (excreted mainly by aquatic animals)
• Urea
• Uric acid

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Osmo-regulationin fishes
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• Terrestrial vertebrates
• Must conserve water
• Endotherms have high metabolic rate
• Produce a large volume of nitrogenous wastes
• Conserve water through efficient kidneys and
  other adaptations

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Excretory organs in terrestrial vertebrates
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• Vertebrate kidney
• Functions in excretion and osmoregulation
• Is vital in maintaining homeostasis
• Its structure and function are adapted to the
  lifestyle of the animal

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The human urinary system
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Structure of the kidney
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Structure of the nephron
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Detailed view of Bowmans capsule
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General regions of filtration, reabsorption, and
secretion
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Filtration membrane of the kidney
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Movement of water, ions, and urea through the
renal tubule and collecting duct
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Concentration of the filtrate as it moves through
the nephron
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• Urine volume is regulated by ADH
• Released by the pituitary gland in response to an
  increase in osmotic concentration of the blood
• ADH increases the permeability of the collecting
  ducts to water
• As a result, more water is reabsorbed

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Regulation of urine volume by ADH
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• Aldosterone andatrial natriuretic peptide work
  antagonistically
• When blood pressure decreases, cells of the
  juxtaglomerular apparatus secrete renin, which
  leads to production of angiotensin II
• Angiotensin II stimulates aldosterone release,
  which raises blood pressure