Thick Ascending Limb/Distal Tubule Renal Transport

Question 1

Is the Thick Ascending Limb permeable to water?

Answer 1

NO

Question 2

What electrolyte is mostly reabsorbed at the Thick Ascending Limb?

Answer 2

Mg - Magnesium

Question 3

Where does a majority of Mg reabsorption occur?

Answer 3

Thick Ascending limb

Question 4

The Thick Ascending Limb is also an important site for reabsorption of Na, K, Ca, and Mg. What transporter on the apical border takes up Na, K, 2Cl?

Answer 4

NKCC2

Question 5

NKCC2 is found where?

Answer 5

Apical border of Thick Ascending limb

Question 6

What is taken up into the cell using NKCC2?

Answer 6

Na+
K+
2Cl-

Question 7

At the Thick Ascending limb, once Na+ is in the cell, how does it get across the basolateral membrane to be reabsorbed?

Answer 7

Na+/K+ ATPase

Question 8

At the Thick Ascending limb, once Cl- is in the cell, how does it get across the basolateral membrane to be reabsorbed?

Answer 8

Cl- channel

Question 9

At the Thick Ascending limb, once K+ is in the cell, what are its 2 options?

Answer 9

1. Leave the cell through a channel at the basolateral border and be reabsorbed
2. Back leak through a ROMK channel at the apical border and re-enter the tubule lumen

Question 10

If K+ inside the cell is going to back leak and re - enter the tubule lumen, what transporter will it use?

Answer 10

ROMK

Question 11

NKCC2 pumps K+ inside the cell from the tubule lumen. ROMK can take K+ from inside the cell and put it back into the tubule lumen. What builds in the tubule lumen if ROMK does this?

Answer 11

K+ = POSITIVE CHARGES

Question 12

As ROMK pumps more K+ back into the tubule lumen, the (+) charges increase. What does this cause?

Answer 12

Mg and Ca to be repelled out of the tubule lumen!!

- They diffuse paracellularly and are reabsorbed!

Question 13

How are Mg2+ and Ca2+ reabsorbed at the Thick Ascending Limb?

Answer 13

Via Paracellular (btwn cells) diffusion caused by repelling the build up of K+ charges inside the tubule lumen due to ROMK on the apical border!

Question 14

This is the site of LEAST amount of solutes being reabsorbed

Answer 14

Distal Tubule

Question 15

Where is the most important site of regulation?

Answer 15

Distal Tubule

Question 16

What are the cell types at the distal tubule?

Answer 16

1. Principal cells
2. Alpha - intercalated cells
3. Beta - intercalated cells

Question 17

What are the hormones involved in regulation at the distal tubule?

Answer 17

Aldosterone

ADH

Question 18

What do the Principal cells at the Distal Tubule REABSORB?

Answer 18

Na+

Water

Question 19

What do the Principal cells at the Distal Tubule SECRETE?

Answer 19

K+

Question 20

What do the Alpha - Intercalated cells at the Distal Tubule REABSORB?

Answer 20

K+

HCO3-

Question 21

What do the Alpha - Intercalated cells at the Distal Tubule SECRETE?

Answer 21

H+

Question 22

What do the Beta - Intercalated cells at the Distal Tubule REABSORB?

Answer 22

H+

Cl-

Question 23

What do the Beta - Intercalated cells at the Distal Tubule SECRETE?

Answer 23

K+

HCO3-

Question 24

Through what transporter on the apical surface do Principal Cells REABSORB Na+?

Answer 24

ENaC

Question 25

What hormone acts on ENaC transporters of Prinicipal cells?

Answer 25

Aldosterone!! | Causes more Na+ reabsorption

Question 26

Where are principal cells, alpha and beta intercalated cells?

Answer 26

Distal Tubule

Question 27

What are the effects Aldosterone has on Principal cells in the Distal Tubule?

Answer 27

INCREASES ENaC transporters for Na+ reabsorption into the cell on the apical border INCREASES Na+/K+ ATPase for Na+ reabsorption on the basolateral border == INCREASED Na+ reabsorption and K+ secretion!

Question 28

This cell in the Distal Tubule reabsorbs Na+ and water, and it secretes K+

Answer 28

Principal cells

Question 29

This cell in the Distal Tubule reabsorbs K+ and HCO3- and secretes H+

Answer 29

Alpha - intercalated cells

Question 30

This cell in the Distal Tubule reabsorbs H+ and Cl- and secretes HCO3- and K+

Answer 30

Beta - intercalated cells

Question 31

What transporter allows for alpha and beta - intercalated cells to exchange K+ and H+?

Answer 31

H - K ATPase

Question 32

At the Distal Convoluted Tubule, what transporter on the apical side takes Ca++ into the cell?

Answer 32

TRPV5

Question 33

Action of TRPV5 at the Distal Convoluted Tubule?

Answer 33

Uptakes Ca2+ into the cell

Question 34

Where is TRPV5?

Answer 34

Distal Convoluted Tubule apical border

Question 35

At the Distal Convoluted Tubule, what transporter on the apical side takes Na and Cl into the cell?

Answer 35

NCC "Thiazide Sensor"

Question 36

Action of NCC transporter at the Distal Convoluted Tubule?

Answer 36

Uptakes Na and Cl into the cell

Question 37

At the Distal Convoluted Tubule, what transporter exchanges Ca reabsorption for sodium to be pushed back into the cell on the basolateral border?

Answer 37

NCE | - Na Ca Exchanger

Question 38

Action of NCE at the Distal Convoluted Tubule?

Answer 38

Reabsorbs Ca and puts Na back into the cell

Question 39

Where is NCC?

Answer 39

Distal Convoluted Tubule apical border

Question 40

Where is NCE?

Answer 40

Distal Convoluted Tubule basolateral border