1. Comparative Vertebrate Physiology
Osmoregulation in Mammals

2. Kidney anatomy

3. Nephron anatomy

4. 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

5. Glomerular filtration
A good marker: Inulin
Renal clearance
GFR x P(In) = U(In) x V

6. Regulation of GFR 3 mechanisms Renal autoregulation Neural control
Renin-angiotension system (JG apparatus)

7. JG apparatus

8. Regulation of GFR

9. Countercurrent multiplication
65%
19%
15%

10. Reabsorption
Sodium moves passively across the apical membrane and actively into the plasma

11. Antidiuretic hormone Arginine vasopressin (mammals)
Posterior pituitary, increases the number of aquaporin water channels in the CD

12. Diuresis Atrial natriuretic peptide (ANP)
Atrium of the heart, decreases Na+ and water reabsorption