1. Urinary and Renal The Countercurrent Multiplier
The Coutercurrent Exchanger
Making Urine
Diuretics
Be able to explain what occurs in the descending and ascending Loop of Henle. (aquaporins and pumps)
What do we mean by a countercurrent?
Be able to describe how the osmotic gradient is used to produce urine of different concentrations.
Be able to discuss diuretics.
Marieb: 25 1

2. Three “Rules” of Osmolarity
(Molarity of compound) x
(How many molecules that compound splits into in solution)
Osmolality adds Up
H2O moves from low to high osmolality

3. The Loop of Henle and the Osmotic Gradient
Descending Limb
Interstitial Fluid
Ascending Limb
1200

4. Aquaporins and the descending LH4

5. Na+/K+ ATPase and the Ascending LH
Na is brought into the cell and kicked out
ATP needed
200 mOsm difference

6. The Loop of Henle and the Osmotic Gradient
Countercurrent Multiplier
1200

7. Take Home Message
Juxtamedullary Loops of Henle set up an osmotic gradient
H2O leaves from the descending arm
Na+ leaves from the ascending arm
Gradient depends on aquaporins and the active transport of Na+

8. Vasa Recta Large, slow moving capillary
Found next to Juxtamedullary Loops of Henle

9. Countercurrent Exchanger
300 mOsm
Maintains osmotic gradient by removing excess H2O
300 mOsm
600 mOsm
600 mOsm
1200 mOsm
1200 mOsm

10. 1200 mOsm
1200 mOsm
1200 mOsm
1200 mOsm

11. Urine Volumes Excess osmolality of 400 mOsm/day Normal Urine
Concentrated Urine
Dilute Urine

12. Diuresis and the Collecting Tube
100
DCT at 100 mOsm
Aquaporins
ADH
300
500
700
900
1100
1200

13. Making Concentrated Urine
100
300
More ADH
More Aquaporins
Less urine
500
700
900
1100
1200

14. Making Dilute Urine Less ADH Less Aquaporins More urine 100 300 500
700
900
1100
1200

15. Diuretics
100
Alcohol
300
500
700
900
1100
1200

16. Loop Diuretics

17. Diuretics
100
Osmotic diuretics
300
500
700
900
1100
1200