Loop Of Henle/ Collecting Duct

Question 0

Ascending limb

Answer 0

Impermeable to water
Na+/2Cl-/K+ symporter
K+ leaks in to lumen->more positive->drives reabsorption
Na+/H+ anti porter leads to HCO3- reabsorption
Sodium pump

Question 1

Descending limb

Answer 1

Highly permeable to water->diffusion

Impermeable to NaCl

Question 2

Early distal tubule

Answer 2

Impermeable to water
Sodium pump in bassolateral membrane
Na+/Cl- symporter, Cl- leaves via diffusion
Ca+ and Mg+ reabsorption
H+ secreted by Na+/H+ exchanger-> bicarbonate reabsorption or buffers

Question 3

Late distal tubule,principal cell

Answer 3

Na+ reabsorption by diffusion and 3Na+/K+ exchanger

Cl- by diffusion

Question 4

Late distal tubule, intercalated cell

Answer 4

Secretion of H+, reabsorption of HCO3- and K+ (K+/H+)

Generation of new bicarbonate because of high carbonic anhydrase

Question 5

Aldosterone

Answer 5

Enhances Na+ reabsorption
Enhances K+ secretion
Enhances H+ secretion

Question 6

ADH

Answer 6

Insertion of AQP 2, mainly in principal cells-> increased water reabsorption. Insertions via vasopressin and cAMP activation.
Also increases permeability of inner medullary collecting duct to urea-> increased urea reabsorption