Renal Transport Mechanisims

Question 1

What are the two types of transport and define them

Answer 1

Trans-epithelial transport - through the membrane

Paraepithelial transport - through the TJ

Question 2

What does the PCT absorb most

Answer 2

Glucose 100%
AA 100% 
Urea 50%
Na 70% 
K 70% 
Phosphate 70% 
Ca 70% 

H2O 70%

Question 3

What does the PST absorb most

Answer 3

Phsophate

Question 4

What does the TDLoH absorb

Answer 4

WATER

Question 5

What does the ThALoH absorb

Answer 5

SOLUTES ONLY!

Na
K
Ca
Mg

Question 6

What does the DCT and CD absorb

Answer 6

Fine tunes the urine, can absorb or not absorb water or solutes

Question 7

Where is most of the water REBS in the nephron

Answer 7

In the PCT

Question 8

What pump powers the REBS of the Na in the PCT

Answer 8

The Na/K Pump

Question 9

Define symporter

Answer 9

Facilitated transport of two or more solutes in the same direction

Question 10

Define antiporter

Answer 10

Movement of two solutes in opposite directions

Pushes one down its gradient and one up its gradient with the use of ATP

Question 11

What does the Na/K Pump create within the cell

Answer 11

A low intracellular Na concentration, thus allowing for Na to move down its gradient

A negative apical side charge which attracts the Na to it

Question 12

transcellular route Transport across the basolateral membrane involves what and why

Answer 12

The lateral intracellular spaces which receive ions as well as the IF

Question 13

How does water move in the PCT through the cells

Answer 13

Through the TJ

Question 14

Na REBS is almost always an active transport where

Answer 14

The transcellular route

Question 15

While the NHE3 moves Na with active transport, how does Na enter the cells with passive transport, and why

Answer 15

Enters via Na leak channels

Using the same reasons as the NHE3, low intracellular Na bc of Na/K Pump

Question 16

With the Na being transported into the cell, what else will come with it

Answer 16

Water

Question 17

How does the water and Na enter the peritubular capillary

Answer 17

Via ultrafiltration, a passive process driven by hydrostatic and colloid osmotic pressure

Question 18

What is the Antiporter used in the PCT to move Na in and H out

Answer 18

NHE3

Question 19

Most of the Na that enter the tubule cells does so how

Answer 19

Via NHE3

Question 20

How does the newly made HCO3 in the cells enter the IF to be taken to the peritubular capillaries

Answer 20

Via a NaHCO3 Co-Transporter

Question 21

How does the Cl concentration behave within the tubule and what does this mean physiologically

Answer 21

Rises as it proceeds which, along with less water and Na from the proximal PCT, allows Cl to freely diffuse across the apical membrane into the cell of the distal PCT.

Question 22

What is the major mechanism for chloride REBS

Answer 22

Paracellular movement

Question 23

What does the presences of TJ’s do in regards to water REBS

Answer 23

Prevents water REBS

Question 24

So where, would you find excessive TJ’s and little or no AQPs (no water permeability)

Answer 24

ThALoH and the CD

Question 25

What do AQPs do

Answer 25

Utilize the transcellular movement of water and allows it pass easier

Question 26

Where is AQP - 1 found

Answer 26

Int he PCT

Question 27

Where is AQP - 2 found

Answer 27

In the CD

Question 28

What is AQP - 2 under the control of

Answer 28

ADH

Question 29

While the PCT has many TJ, it also has what which allows it top be permeable to water

Answer 29

AQP - 1

Question 30

All water REBS is what

Answer 30

Passive

Question 31

Glucose is REBS via what type of transport

Answer 31

Active

Question 32

# Define SGLT1 Where is it located, what is its physiological status, and what GLUT does it go with

Answer 32

Is a high affinity, low capacity transport protein that is found in the distal PCT S3 region on the apical side Because it is high affinity, is used to pick up what glucose is left behind from SGLT2 in the proximal PCT, which means it can operate at low concentrations Is paired with GLUT1on the basolateral membrane side

Question 33

Define SGLT2 and it’s physiological status

Answer 33

Is found in the S1 and S2 parts of the PCT. Is a low affinity, high capacity transporter which allows the proximal PCT to REBS most of the glucose Links the movement of Na down its concentration gradient with the uphill REBS of glucose, even when glucose concentration inside the cell is higher than tubular fluid concentration Is paired with GLUT2

Question 34

What happens if the SGLTs reach their Tm

Answer 34

No more Glucose can be REBS, thus the patient has way too much Glucose in their blood and this is indicated by the presence of Glucose in their urine

Question 35

What does the TDLoH REBS and what does this mean physiologically

Answer 35

REBS WATER NOT SOLUTES This means as the TF moves along, it becomes more concentrated until reaching the ThALoH This movement of water is caused by the increased osmol. Of the If from the REBS of solute from the ThALoH

Question 36

The TALoH and ThALoH REBS what and not what and what is the physiological consequence of this

Answer 36

REBS 40% of Na and Cl NOT WATER This means the TF becomes much less concentrated as it approaches the DCT because the solutes are being REBS

Question 37

Is Na REBS linked to other solutes within the ALoH?

Answer 37

No

Question 38

Define the NKCC2 transporter and why it acts the way it does

Answer 38

Is a symporter which moves 1 Na, 1 K, and 2 Cl into the cell from the apical side Is able to do this bc of the gradient est. but the Na/K pump

Question 39

Due to the Na/K pump moving Na out of the cell, what is made on the apical membrane and what does this allow for

Answer 39

A (-) charge is made which allows for the movement of Na, Ca, and Mg via paracellular REBS

Question 40

Define the NCC transporter and what it does physiologically

Answer 40

Is a Na/Cl co transporter in the DCT which REBS NaCl when told to do so by Aldosterone

Question 41

How does Thiazide work

Answer 41

Inhibits the REBS of Na and Cl in the DCT by acting on the NCC and inhibiting it, thus allowing for more NaCl in the TF and more water concequently It also increases Ca REBS which helps to treat Ca kidney stones

Question 42

How do Loop Diuretics work

Answer 42

Inhibits the NKCC2 transporter in the THALoH which causes a decreased REBS of Na, K, and Cl and also diuresis

Question 43

How do K + Sparing Spironolactone work

Answer 43

Inhibits Na/K echange in the DCT and CD which promotes K retention, Na retention, and water loss