Unit 5 Lecture 35 Flashcards Preview

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Flashcards in Unit 5 Lecture 35 Deck (20)
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1
Q

Define countercurrent mechanisms

A

mechanisms that require a countercurrent flow and osmotic gradient

2
Q

Define countercurrent flow

A

Within a tubule, (ie loop of henle) there are opposing flows that counteract one another

ex: descending is permeable to water and ascending is not

3
Q

Define osmotic gradient

A

Within fluid outside of the tube, there is a different is osmotic charges between the extratubular fluid and the fluid inside the tube

4
Q

What two processes are examples of countercurrent mechanisms?

A
  • countercurrent multiplication

- countercurrent exchange

5
Q

What does countercurrent multiplication deal with?

A

Nephron and ISF

6
Q

What does countercurrent exchange deal with?

A

Vasa recta and ISF

7
Q

How is an osmotic gradient built?

A
  1. Permeability differences in different sections of loop an CD
  2. Countercurrent flow of tube fluid through des/asc/ limbs
8
Q

What is the descending limb permeable to and why?

A

Water - higher osmolarity of fluid outside limb causes water to move out through osmosis

9
Q

What is thick ascending limb permeable to and why?

A

Solutes - symporters reabsorb Na/K/Cl

10
Q

What is the late DCT and CD permeable to?

A

water in the presence of ADH

11
Q

What direction does the descending and ascending limb carry fluid?

A

descending - Down

ascending - up

12
Q

What are the 3 major solutes involved in osmotic gradient?

A

Na/Cl/Urea

13
Q

Part 1. of countercurrent multiplication

A

Symporters in thick ascending cause a buildup of Na and Cl in renal medulla

14
Q

Part 2. of countercurrent multiplication

A

Countercurrent flow through descending and ascending limns make an osmotic gradient in renal medulla

15
Q

Part 3. of countercurrent multiplication

A

cells in CD reabsorb more water and urea

16
Q

Part 4. of countercurrent multiplication

A

Urea recycling makes buildup of urea in renal medulla

17
Q

What is urea recycling?

A

Urea leaves the CD (gets reabsorbed) due to intercalated cells and this urea concentration in the ISF causes more water to leave (be reabsorbed) in the descending limb ——> concentrated urine

18
Q

What happens during countercurrent exchange of vasa recta and ISF?

A

similar countercurrent flow and osmotic gradient

19
Q

Overall purpose of the countercurrent multiplication

A

establishes osmotic gradient through the long loop of henle

20
Q

Overall purpose of the countercurrent exchange

A

maintains the gradient by delivering nutrients to nephron cells through the vasa rects