Bits Of Nephron

Question 1

Loop of henle

Answer 1

15-25 percent NaCl
Urinary concentration
Magnesium reabsorption
Calcium reabsorption 
Urea recycling from the collecting duct

Question 2

Target loop diuretics?

Answer 2

na/K/2Cl cotransporter apical membrane thick ascending limb

Question 3

Distal convoluted tubule

Answer 3

5 percent NaCl

Magnesium

Question 4

Collecting duct

Answer 4

Salt and water balance
4-5 percent water
Principal cells absorb Na, secrete K, are where aldosterone and K sparing diuretics act
Type A intercalated cells mediate acid secretion and bicarbonate reabsorption under influence aldosterone
Type B inter calated cells mediate bicarbonate secretion and acid reabsorption
Urea recycling

Question 5

Liddles syndrome

Answer 5

Activating mutation in ENaC - epithelial sodium channels on principal cells - produces increase na reclamation and hypertension, Hypokalaemia, metabolic alkalosis

Note trimethoprim and pentamidine block ENaC and predispose to hyperkal

Question 6

K sparing diuretics

Answer 6

Na reabsorption creates electrical gradient in tubule and k follows down gradient
If block na reabsorption, K secretion blunted

Question 7

ANP and RNP

Answer 7

Apical or basolateral receptors on inner medullary cD cells –> increase cGMP–> reduces activity apical Na channel–> natriuresis

Question 8

Proximal tubule

Answer 8

Proximal tubule reason 60 percent NaCl and water 
Filtered bicarbonate 90percent 
Chloride re absorption
Most of glucose re absorption
Secrete organic acids and bases
Resorb amino acids 
Ammoniagenesis