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Flashcards in 4.4_2 Renal II Deck (35):
1

Does the medulla have high or low osmolarity?

HIGH

2

Osmolarity =

Osmoles / liter

3

What is the osmolarity of 150 nM NaCl? (in most / L)

300

4

What is the medulla's saltiness due to?

The countercurrent multiplier system in the Loop of Henle

5

Three essential features of the countercurrent multiplier system in the Loop of Henle

1. Filtrate countercurrent
2. Differential water permeability
3. Countercurrent blood flow

6

Filtrate countercurrent

Tubular fluid flows in the opposite direction in descending and ascending limbs

7

Differential water permeability

Ascending and descending limb have different permeabilities to water

8

Is the ascending limb permeable to water?

No, it is thick and impermeable to water

9

What does the ascending limb do?

Actively transports ions out of the tubular fluid into the interstitial space

10

Is the descending limb permeable to water?

Yes, the entire limb is permeable to water

11

Countercurrent blood flow

Blood in vasa recta also flows in opposite direction to the tubular fluid

12

In the ascending limb, __________ transport NaCl at ________ membrane... drags NaCl out of filtrate across _______ into ________

ATP driven pumps
Basolateral
Tubule epithelial cells
Interstitial space

13

First step of counter current multiplier

Pumps Na+ from filtrate into surrounding interstitial space
*Water can't follow*

14

Is filtrate entering the DCT dilute or salty?

Dilute

15

What happens with the vasa recite near the ascending limb?

Water from plasma chases salt into interstitial space, vasa recta plasma becomes saltier as it heads towards descending limb

16

Why does the water in filtrate move out in the descending limb?

Because it is
Chasing salt pumped out by ascending limb in interstitial space
Chasing salty blood in vasa recta

17

Vasa recta by the descending limb

Some salts leave chasing water from filtrate (adds salt to interstitial space)

18

What happens to the water left in the vasa recta

Re-enters blood, gets whisked aways to the heart

19

The combination of the Loop of Henle and vasa recta capillaries establish...

An osmotic gradient

20

What is the osmolarity of the interstitial fluid at the base of the Loop of Henle?

~1200 mOsmoles
-Super salty!

21

Is the filtrate salty or dilute at the base of the loop of Henle?

Very salty, but it does not matter because the salt will be extracted as it rises up the ascending limb

22

The filtrate is ~___mOsmoles ay the end of the Loop

100

23

Blood Osmolarity is regulated by...

Water retention (ADH)

24

Blood volume is regulated by

Retention of salts
Na, K (Aldosterone and Atrial Natriuretic Petide))

25

Sensor cells for osmolarity are in the...

Hypothalamus.. ADH neurons

26

Effectors for osmolarity regulation

The epithelial cells lining the collecting duct express ADH receptor

27

The hypothalamic cells release _____ which controls how _______ the ______ is to water

ADH
Permeable
Collecting duct

28

Hypothalamic _______ integrate signals for osmolarity

Osmoreceptors

29

ADH is produced in ________ cells in hypothalamus and released in _________

Neurosecretory
Posterior pituitary

30

_______ cells in collecting duct respond to ADH by increasing expression of _______

Principal
Water channels (aquaporins)

31

Water deficit = _______ --> Stimulates high plasma _____ --> Promotes water reabsorption in ________

High osmolarity
ADH
Collecting duct

32

Do collecting ducts have more or less aquaporins open when ADH is expressed?

More, this makes it more permeable to water

33

Why does water leave the collecting duct and enter the interstitial fluid?

Because of the saltiness that the Loop of Henle creates

34

Water excess = ______, low plasma _____ --> Water lost to the urine

Low osmolarity
ADH

35

When ADH is not expressed, collecting ducts are _____ to water, causing..

Impermeable
Water to pass by the salty medulla