17.11 Physiology: Kidney function and electrolyte balance

Question 1

How does water move out of the tubule?

Answer 1

Osmotically, bulk flow

Question 2

What do the early and late PT specifically reabsorb?

Answer 2

Early: bicarb

Late: chloride

Question 3

What is the voltage in the lumen of the late PT?

Answer 3

+3 mV (due to Cl concentration)

Question 4

What is the Na reabsorption like in the early and late PT?

Answer 4

Early PT: negative lumen voltage, little Na reabsorbed

Late Pt: Na outflow, 50% paracellular, 50% trans-cellular

Question 5

How is Na+ reabsorbed in the thin ascending limb?

Answer 5

Via passive diffusion across tight junctions (paracellular)

Question 6

What do thiazides target?

Answer 6

NaCl co-transporter (distal covoluted tubule)

Question 7

What do loop diuretic target?

Answer 7

Na/K/2Cl co-transporter

Question 8

What does Amiloride target?

Answer 8

Epithelial sodium channel (collecting duct)

Question 9

What is Frusemide often given with?

Answer 9

K+ supplements

Question 10

How is Na reabsorbed in the distal tubule?

Answer 10

Completely by transcellular route

Question 11

What do the waste products/xenobiotics use to enter late PT cells?

Answer 11

Roat1 (organic anion exchanger)

Question 12

How do we retain H+ on the basolateral membrane?

Answer 12

MCT

Question 13

How do we retain Na+ on the apical membrane?

Answer 13

NaDC1

Question 14

What is the difference between the ascending/descending limb at any point (before multiplication)?

Answer 14

200mOsM

Question 15

What inserts aquaporins?

Answer 15

ADH

Question 16

Where does aldosterone get released from? What does this do?

Answer 16

From adrenal cortex, increases sodium reabsorption (distal tubule)

Question 17

What does Ang II do in the kidneys? (3)

Answer 17

Constricts efferent arteriole (increase GFR)

Increases proximal tubule sodium reabsorption (upregulation of Na/H+ exchanger)

Acts on mesangial cells on glomerulus to contract(regulate GFR)