Renal Transport Mechanisms

Question 1

What is reabsorption powered by?

Answer 1

the Na-K-ATPase

Question 2

what are the symporters associated with Na+?

Answer 2

glucose, amino acids, Pi, and HCO3-

Question 3

what are the antiporters associated with Na+?

Answer 3

H+ and organic solutes

Question 4

How does Na+ cross the basolateral border?

Answer 4

via the Na-K-ATPase

Question 5

what transporter does the Na-glucose use on the apical membrane in the PCT?

Answer 5

the SGLT

Question 6

what transporter/exchanger does the H+/Na+ use on the apical membrane in the PCT?

Answer 6

the NHE

Question 7

what transporter does glucose use on the basolateral membrane?

Answer 7

GLUT

Question 8

How is water reabsorbed transcellularly in the PCT?

Answer 8

via AQP channels

Question 9

how is water reabsorbed paracellularly in the PCT?

Answer 9

passively

Question 10

where does most reabsorption of Mg2+ take place?

Answer 10

in the TAL

Question 11

What is present on the apical membrane of the TAL?

Answer 11

NKCC2 and ROMK channels

Question 12

How does Na get out of the TAL cells?

Answer 12

through the Na-K-ATPase

Question 13

how does Cl- get out of the TAL cells?

Answer 13

through a Cl- channel

Question 14

how does K+ get out of the TAL cell?

Answer 14

either through a K+ channel on the basolateral membrane or through the ROMK channel that is on the apical membrane and back into the tubular lumen

Question 15

What is the result of the K+ being secreted back into the tubular lumen of the TAL through the ROMK?

Answer 15

there will be a + charge build up in the TAL especially as we ascend

Question 16

what does the buildup of the positive charge in the TAL cause?

Answer 16

Ca2+ and Mg2+ will squeeze out through paracellular diffusion

Question 17

what is the most important site for regulation of the nephron?

Answer 17

the distal tubule

Question 18

what are the cell types involved in the distal tubule?

Answer 18

principal cells, alpha-intercalated cells, and beta-intercalated cells

Question 19

What do the principal cells reabsorb?

Answer 19

Na+ and H2O

Question 20

what do the principal cells secrete?

Answer 20

K+

Question 21

what do the alpha intercalated cells reabsorb?

Answer 21

K+ and HCO3-

Question 22

what do the alpha intercalated cells secrete?

Answer 22

H+

Question 23

what do the beta intercalated cells reabsorb?

Answer 23

H+ and Cl-

Question 24

what do the beta intercalated cells secrete?

Answer 24

K+ and HCO3-

Question 25

What is the concentration of the tubular fluid in the DCT?

Answer 25

since the DCT is impermeable to H2O and NaCl is continuing to be reabsorbed, the tubular fluid in the DCT becomes diluted

Question 26

how does NaCl cross the apical membrane in the DCT?

Answer 26

via the Na-Cl-cotransporter (NCC)

Question 27

What is the NCC sensitive to?

Answer 27

thiazide

Question 28

How does Ca2+ cross the apical border in the DCT?

Answer 28

via the TRPV5 channel

Question 29

How does Ca2+ cross the basolateral membrane in the DCT?

Answer 29

via the Na-Ca exchanger (NCE)

Question 30

where are the principal cells located?

Answer 30

in the late distal tubule and collecting ducts

Question 31

What is located on the apical membrane of the principal cell of the late distal tubule/collecting duct/ how is Na+ reabsorbed in the principal cells?

Answer 31

via the ENaC

Question 32

What is located on the apical membrane of the principal cell of the late distal tubule/collecting duct that helps with K+ secretion?

Answer 32

an ROMK channel

Question 33

What effect does aldosterone have on the principal cells?

Answer 33

aldosterone is going to increase the expression of the ENaC and Na-K-ATPase, which increases Na+ reabsorption and increases K+ secretion

Question 34

How is K+ secreted in the principal cells and beta-intercalated cells?

Answer 34

passive diffusion out of the cell into the tubular lumen or through ROMK channels or BK channels

Question 35

how do alpha-intercalated cells reabsorb K+?

Answer 35

through a H-K-ATPase on the apical membrane to get into the cell and then it passively diffuses across the basolateral membrane