* Group Cases

Question 1

What changes in body fluids can cause changes in ADH release?

Answer 1

1) Small INC in plasma osmolarity (osm drop shuts off ADH release)
2) Large drop in plasma volume
3) Stress/nausea

** Alcohol inhibits ADH **

Question 2

What mechanisms control the specific gravity of urine?

Answer 2

6 things required for concentrating urine - long Loops of Henle - NaCl pump in thick ascending limb - Different permeabilities of descending/ascending limbs - ADH - Urea recycling - Low medullary blood flow (vasa recta)

Question 3

Normal range of urine osmolarity

Answer 3

50-­‐1200 mOsm/mL

Question 4

What limits ability to concentrate urine?

Answer 4

Limitations on the maximum concentration of urine: – length of LOH (the further into the medulla it travels, the more concentrated interstitium it encounters, thus allowing more concentrated urine) – strength of the Na/Cl active pumps.

Question 5

If giving ADH produces less urine, but inducing ADH does not work what does that mean? (don’t give pt water, see if they get thirsty, or produce less urine)

Answer 5

Means the problem is not in the kidney – extrarenal issue

Question 6

Osmotic diuresis

Answer 6

• excreting glucose in urine - reduced glucose reabsorption causes reduced water reabsorption (water is reabsorbed alongside glucose)–> polyurea

Question 7

Glucose reabsorption from apical membrane of tubule uses _______, and ______ on basolateral side

Answer 7

Na+/Glucose symport – apical GLUT2 transporter – basolateral