Renal Phys ML: 6

Question 1

What are the two routes water can take to be reabsorbed?

Answer 1

paracellular and transcellular

Question 2

What is the main water route in proximal tubule

Answer 2

paracellular

Question 3

What is the main water route in the collecting ducts

Answer 3

transcellular

Question 4

Which route requires aquaporins

Answer 4

transecullar because it has to go through the cell

Question 5

How are aquaporins regulated

Answer 5

by ADH

Question 6

Diuresis

Answer 6

loss of fluid via urine

Question 7

What secretes adh

Answer 7

posterior pituitary

Question 8

What does ADH do

Answer 8

secretes more aquaporins and it reduces amount of water in urine by increasing reabsorption

Question 9

Where is AQP2 located

Answer 9

on the apical membrane

Question 10

Where are AGP3 and 4 located

Answer 10

on the basolateral membrane

Question 11

Proximal Tubule:

Answer 11

Na+ reabsorption is high and constant (non regulated)
H20 permeability is high and constant (not regulated)
Reabsorption of Na+ and H20 are coupled

Question 12

Descending Loop of Henle

Answer 12

H20 reabsorption is high and constant (not regulated); No Na+ reabsorption

Question 13

Ascending Loop of Henle

Answer 13

Na+ reabsorption is high and constant ( not regulated); No H20 reabsorption

Question 14

Collecting duct

Answer 14

Na+ reabsorption is variable, is regulated by aldosterone and is NOT directly couple to water reabsorption
Water permeability is variable is regulated by ADH and requires the renal medullary gradient

Question 15

What creates and maintains the renal medullary gradient?

Answer 15

juxtamedullary nephrons with long loops of henle

Question 16

What relies on the gradient?

Answer 16

all nephrons flow through it and rely on it for water reabsorption

Question 17

As you go deeper into the medulla what happens

Answer 17

osmolarity increases

Question 18

What two mechanisms create the gradient

Answer 18

countercurrent multiplier system
urea recycling

Question 19

What is the mechanism that maintains this gradient

Answer 19

vasa recta circualtion

Question 20

What is the highest possible concentration at the bottom of the medulla

Answer 20

1400 mOsm

Question 21

How does the vasa recta maintain the gradient

Answer 21

it returns reabsorbed water and solutes to the circulation, without washing out the gradient

Question 22

What is happening in the vasa recta circulation

Answer 22

solutes keep getting exchanged between ascending and descending vasa recta and are trapped in the medulla