Urine Concentration and Dilution Flashcards Preview

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Flashcards in Urine Concentration and Dilution Deck (32)
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1

What is ADH?

Antidiuretic hormone

  • Produced in pituitary gland in response to high osmolarity sensed by osmoreceptors in hypothalamus (triggers release of ADH)
  • Affects collecting duct  to place aquaporins to increase H2O reabsorption 
  • brings osmolarity back down to 300 mOsm

2

Descending loop of henle is a ____ segment

concentrating

Permeable to H2O, impermeable to solutes

3

Thick asending limb of henle's loop are _____ segments?

Diluting

Permeable to solutes, impermeable to H2O

4

Where is the majority of loop of henles?

Juxtamedullary- mainly in medullary interstitium

Cortical nephron (majority)- mainly in cortex

5

Which nephrons are responsbile for creating concentration gradient?

Juxtamedullary

6

All collecting ducts run though the  _____

medulla

7

60-70% of filtrate is reabsorbed in the ___ ___.

Proximal tubule

8

At end of proximal tubule, osm in nephron is ____

300 mOsm (isoosmotic d/t absorption of solute and H2O)

9

What is osm at bottom of loop of henle?

>300 mOsm. Can be as high as 1200

10

What is the osm at end of ascending loop of henle?

100-150 d/t dilution from absorption of solutes

11

What is reabsorbed in distal tubule?

  Na, Ca, Cl reabsorbed. K secreted

12

What is osm at end of distal tubule?

hypoosmotic

13

What happens in collecting duct without ADH?

Only absorbs solutes. Urine will be hypotonic

14

What happens in collecting duct with ADH?

Reabsorb H2O via aquaporins

Also absorb solutes

Make hypertonic urine

15

What affects ADH release?

  • OSM
  • Decreased BP
  • Cold

16

ADH allows water to leave duct only if the area is ____

concentrated

17

What is the medullary countercurrent multiplier system?

  • What creates osmotic gradient in the loop of henle
  • U-shape is essential for its function (creates countercurrent essential to establishing osmotic gradient)

18

Where does the change in concentration gradient start in the loop of henle?

Starts in ascending loop of henle by Na/Cl/K transporter creating 200mOsm gradient (that transporters Tmax) between ascneding loop of henle and interstitium

19

What happens after osmotic gradient is created in ascending loop?

The interstitium (which is 200 mOSM higher than ascending limb) equalizes with descening limb (making it 400 mOsM as well)

20

What are the drivers of the concentration gradient in the loop of henle?

Ascending limb transporters 

21

What is the Tmax of the acending limb transporters (NA/CL/K)

Max 200 mOsm gradient

22

In loop of henle, the more fluid we move, the more the gradient will

increase

23

24

How does collecting duct become hypertonic?

It will equilibrate with whatever the osmolarity is in the interstitium (interstitium is same osm on both sides of ascending loop of henle)

When ADH present, aquaporin channels are placed and water will move to concentration gradient, concentrating urine

25

Urea contributes to about ___ of th eosmolarity

40%

26

Urea is _____ and gets ____ in gradient and contributes to gradient.

recycled; stuck

27

What is the vasa recta?

U-shaped capillaries around loop of henle

28

Why is the vasa recta u-shaped?

So that nutrients won't be washed away. Maintains concentration gradient and keeps solutes where they area

29

Main characteristics of vasa recta?

  • preserves concentration gradient created in medulla
  • also has countercurrent
  • maintains low blood flow so gradient won't be washed away

30

The vasa recta is also called the ___ ___ ___

counter current exchanger