Comparative Vertebrate Physiology

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Comparative Vertebrate Physiology

• Osmoregulation in Mammals

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Kidney anatomy
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Nephron anatomy
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Glomerular filtration rate

• Total amount of filtrate formed per minute
• Measured by a marker
• Characteristics
• Freely filtered by the glomerulus
• Not reabsorbed or secreted
• Must not alter GFR

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Glomerular filtration

• A good marker Inulin
• Renal clearance
• GFR x P(In) U(In) x V

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Regulation of GFR

• 3 mechanisms
• Renal autoregulation
• Neural control
• Renin-angiotension system(JG apparatus)

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JG apparatus
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Regulation of GFR
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Countercurrent multiplication
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15
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Reabsorption

• Sodium moves passively across the apical membrane
  and actively into the plasma

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Antidiuretic hormone

• Arginine vasopressin (mammals)
• Posterior pituitary, increases the number of
  aquaporin water channels in the CD

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Diuresis

• Atrial natriuretic peptide (ANP)
• Atrium of the heart, decreases Na and water
  reabsorption