16. Transport in the distal connective tubule and the collecting tubule

Question 1

connecting tubule (CNT)+ cortical collecting tubule (CCT) =

Answer 1

mineralcorticoid dependent Na+ reabsorption

Question 2

cortical collecting tubule (CCT)

Answer 2

ADH-dependent water reabsorption

Question 3

carbon chain length (MCT)

Answer 3

ADH-dependent water and urea reabsorption,
ANP-dependent Na+ excretion

Question 4

Mineral corticoid dependent Na+/K+ transport: what pumps are present

Answer 4

Basolateral sodium/potassium pump and luminal sodium and potassium channels.

Question 5

Mineral corticoid dependent Na+/K+ transport: Na+ channel inhibited by

Answer 5

amiloride

Question 6

Mineral corticoid dependent Na+/K+ transport: potassium transport

Answer 6

The transport of potassium is passive in both directions: luminal (secretion) and basolateral (reabsorption).

Question 7

Mineral corticoid dependent Na+/K+ transport: Potassium excess

Answer 7

potassium is in excess = z. glomerulosa produce more aldosterone = more luminal Na+ and K+ channels are expressed

Question 8

Active water transport: how does h20 move

Answer 8

paracellularly

Question 9

Active water transport: CCT and MCT

Answer 9

In CCT and CNT or MCT sections:
the water transport is a hormonally regulated process which is linked to the special water channel protein of the principal cells (aquaporin-2)

Question 10

Acid-base balance: who is the most important tubule to maintain the regulated acid/base balance

Answer 10

CCT AND CNT

Question 11

Acid-base balance: Intercelar cells

Answer 11

Potassium secretion (hydrogen pump) and hydrocarbonate reabsorption goes on

In case of alkalosis: significant independent
hydrocarbonate production and secretion occurs.

Question 12

Acid-base balance: Defence agains acidosis step 1

Answer 12

The H+ of the water of the cell is
forwarded to the lumen by electrogenic luminal H+ pump (ATPase).

Question 13

Acid-base balance: Defence agains acidosis step 2

Answer 13

• The carbonic anhydrase unites the CO2 entering from the blood side with the OH group.

Question 14

Acid-base balance: Defence agains acidosis step 3

Answer 14

• The formed new HCO - is carried 3 out to the blood by the Cl-/HCO - antiporter. The Cl- 3
  leaves through a passive channel.

Question 15

Acid-base balance: Defence against alkalosis step 1

Answer 15

H+ ion originating from the dissociation of water on the basolateral side is removed by the H+/K+ ATPase pump to the interstitium.

Question 16

Acid-base balance: Defence against alkalosis step 2

Answer 16

The HCO -/Cl- antiporter located on 3 the luminal side removes HCO - 3 from the cell into the lumen

Question 17

Acid-base balance: Defence against alkalosis step 3

Answer 17

The excess potassium accumulated in the cell through a passive K+ channel gets back to the interstitium.

Question 18

K+ transport: what is it

Answer 18

The potassium ion concentration of the plasma is regulated very precisely by the organism, as its concentration change affects all irritable tissues

Question 19

K+ transport: In CCT

Answer 19

CCT principal cells: reabsorption of sodium and mineralcorticoid dependent secretion of potassium.

Question 20

K+ transport: in CNT

Answer 20

CCT intercalary cells: reabsorption with H+/K+ exchange.