Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Phsyiology 210 B > Renal 3. Water Balance: Water Reabsorption Medullary Osmotic Gradient (Countercurrent Multiplier) > Flashcards

Renal 3. Water Balance: Water Reabsorption Medullary Osmotic Gradient (Countercurrent Multiplier) Flashcards

1
Q

Water input and output is ~

A

2.5L / day, 2.5L go in and 2.5L go out.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What’s are the roles of the kidneys in water balance

A

They reabsorb a lot of water, increase reabsoption when we are dehydrated, or stop reabsroption when we are fully hydrated.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Do we secreted water?

A

We never secrete water. No active water movement, all done by concentration gradients (osmolarity), following NaCl and protein.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How os water balance done, how is it moved?

Transporters?
Pumps?
Gradients?
Channels?

A

all done by concentration gradients (osmolarity), following NaCl and protein.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Countercurrent multiplication :

A

The process of using energy to generate an osmotic gradient that enables you to reabsorb water from the tubular fluid and produce concentrated urine.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How many litres are lost out of the body in one day, total losses

A
  • Feces = 0.1L
  • Other losses 0.9L
  • Urine = 1.5L
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

The Kidney Can Generate a Urine as Dilute as

A

30 mOsm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

The Kidney Can Generate a Urine as concentrated as

A

1200 mOsm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What’s the formula for osmoles extracted/day?

A

Osmoles excreted/day (1200 If dehydrate or 30 if hydrated) =

(urin osmolarity Uosm) X ( urin output/day V)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the formula for urine osmolarity

A

Urine osmolarity Uosm =

(Osmol excreted/day) 600 mOsmol/day
——————————— = ————. =
(urin output/day V). 1.5L/day

400 mOsm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Osmolarity gives indication of how

A

many solutes dissolved in solution.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Osmolarity can go up either by:

A
  1. Adding concentration of. Solute

2. Lower concentration of water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

For proper function, regardless of hydration, one requires an osmoles level of ______/day

A

600 /day.

If not 600, serious problem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Normal urine osmolarity should be

A

400 mOsm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Known urine osmolarity is slightly

A

hyper osmotic compared to blood plasma which is around 300

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What’s the formula for urine volume output /day?

A

Osmol excreted /day
——————————- V (urine output)
Uosm.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

For extreme water dieresis, what’s the volume of urine excreted / day ?

A

Osmol excreted /day 600mOsm/day
——————————- = ——————. =
Uosm. 30mOsm

20L/day

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

For extreme water dieresis, what’s the volume of urine excreted / day ?

A

Osmol excreted /day 600mOsm/day
——————————- = ——————. =
Uosm. 1200mOsm

0.5 L/day

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the absolute maximums for urine volume excretion?

A

Max hydrated —> 20 L/day

Max dehydrated —> 0.5 L/day

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Medullary Osmotic Gradient (Countercurrent Multiplier)

A

This how the kidney creates the environment in the medulla required so that when we do need to reabsorb more or less water, via the countercurrent multiplier system.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

In the proximal tubule, Tubule Fluid (TF) Is

A

Isosmotic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

By the time water reaches the end of the loop of henle,

A

Become diluted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Once water passes through the loop of henle, it goes through the collecting tubules (CCT, OMCD, IMCD), where it will

A

Either remain Diluted or becomes concentrated.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How does the distal tubule know when to make it concentrated or diluted?

A

Tells the Kidneys/nephrons (at the distal tubule) to reabsorb more or less water depending on hydration status.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Isosmotic:

A

Means that concetration of solvent and solute are EQUAL.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is isosmotic osmolarity # and where’s it found?

A

300 and found in proximal tubule.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Steps for water passing through the nephron

A

1) Proximal tubule
2) Loop of henle
3) Distal tubule
4) Collecting tubules (CCT, OMCT,IMCDT)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Steps for water passing through the nephron

1) Proximal tubule:

A

isosmotic, reabsorb 70% remaining 30% reabsorbed throughout the rest of nephron.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Steps for water passing through the nephron

2) Loop of henle

A

No matter hydration status, INCREASE in tubular fluid as it does down the DESCENDING limb.

30
Q

How does the loop of henle cause an increase in tubular fluid ?

A

Because THIN Ascending limb is ALWAYS permeable to H2O, no matter. No movement of solutes at the ascending.

THIN ascending reabsorb H2O into tubule = Osmolarity increases (HYPERTONIC) [300]

THICK Ascending limb (impermeable to H2O) Adds solutes = DECREASES osmolarity [200]
———->
Goes back down to be HYPOSMOTIC (LESS solutes, osmoles goes from 300 —> 200).

31
Q

When you add / removed solutes, what happens to osmolarity?

A
  • Add solutes = solutes increase = hypertonic (lower osmolarity)
  • remove solutes = solutes decrease = hypotonic (higher osmolarity)
32
Q

Steps for water passing through the nephron

3) Distal Tubule

A

At the beginning of the distal tubule, kidneys are signalled to either reabsorb water or not

  • becomes permeable to water to do so.
33
Q

Is the distal tubule permeable to water ?

A

Usually its not but it can become permeable if its told to reabsorb water (if dehydrated)

34
Q

When the distal tubule decides to :

A) reabsorb water
B) not reabsorb after

A

A) reabsorb water: osmolarity increases cuz more fluid

B) not reabsorb after : osmolarity decreases cuz less fluid

35
Q

Steps for water passing through the nephron

4) Collecting Tubules (CCT,OMCD,IMCD)

A

Two cases:
A)H2O reabsorbed. B)No reabsorption

A)H2O reabsorbed: distal tubule signals the collecting tubules to add more H2O = increases reabsorption (osmolarity increases)

B) NO reabsorption: distal tubules DOESNT signal the collecting tubules, so NO reabsoption of H2O (osmolarity decreases)

36
Q

If the collecting tubules were signalled by the distal tubule to reabsorb water, the urine will be

A

Concentrated (1200)

High solutes and low H2O

37
Q

If the collecting tubules were NOT signalled by the distal tubule to reabsorb water, the urine will be

A

Diluted (30)

High H2O
LOW solutes

38
Q

Depending on the hydration status, the kidneys/nephron will create a

A

Environment in the medulla nephron that’s favourable for the hydration status,

  • Water reabsorption if dehydrated
  • NO water reabsorption if hydrated
39
Q

How is the THIN descending limb permeable to water ?

A

Through AQP-1 transporter that allows to reabsorb H2O, present in the environment at all times, not matter.

40
Q

The steps to change environment in medulla

A

1) . Fluid enters —> active transport of Na+, Cl-, K+ ions into medullary interstitial fluid = increases osmolarity [300]
2) . Water moves out of DESCENDING limb by osmosis
3) . DESCENDING limb is iso-osmotic; osmotic differences between descending [400] and ascending [200]
4) . More fluid enters tubule = pushes fluid via bulk flow. ——> active transport of Na+, Cl-, K+ ion into medullary interstitial fluid (outside tubule) = osmolarity increases in the interstitial space to [400]
5) . Water moves out of DESCENDING limb by osmosis = changes osmolarity of medullary space [300/400—> 350/500]
6) iso-osmotic state in DESCENDING limb; osmotic difference between descending and ascending [350/500 —> 300/150]
7) more water enters tubule, process continues. System is in ready state, the osmotic gradient has been established.

41
Q

The steps to change environment in medulla

STEP 1)

A

Fluid enters —> Na+, Cl-, K+ ions moved into medullary space (via active trasport) by the THICK ascending limb
= increases osmolarity [300]

  • enter system at this point is isosmotic
    [everything is @ 300]
42
Q

The steps to change environment in medulla

STEP 2)

A

2). Water moves out of DESCENDING limb by osmosis

  • medullary space osmolarity increases
    [from 300–> 400]
  • the removed solutes from the THICK ascending limb causes decrease in osmolarity [from 300 —> 200]

** we now have favourable env for water reabsorption from THIN descending limb to medullary space —-> blood **

43
Q

Where do all the things in the medullary space end up?

A

In the blood

44
Q

The steps to change environment in medulla

STEP 3)

A

3) . DESCENDING limb is iso-osmotic; theres an osmotic differences between descending [400] and ascending [200]
- THIN descending osmolarity increases cuz of reabsorbed H2O = [400]
- Ascending limbs osmolarity decreases [from 300 —> 200]

45
Q

The steps to change environment in medulla

STEP 4)

A

4) . More fluid enters tubule = pushes fluid (via bulk flow). ——> active transport of Na+, Cl-, K+ ions by the THICK ascending limb into medullary interstitial fluid (outside tubule) = osmolarity increases in the interstitial space to [400]
- new fluid causes early THIN descending osmolarity to decrease = [300 —> 300/400]

  • new fluid causes early THICK ascending limb causes osmolarity increase =
    [200 —> 400/200] (this is the reason why the THICK ascending osmolarity is ALWAYS low) creates H2O reab ravorbale env
46
Q

How is fluid pushed down the tubule?

A

Via bulk flow

47
Q

At what step do we gain an env that’s favourable for water reabsorption at the thin descending limb? Why?

A

Step 2 because of the bulk flow of fluid pushed down the tubule = osmolarity of THIN dl decreases/

48
Q

The steps to change environment in medulla

STEP 5)

A

5) . Water moves out of DESCENDING limb by osmosis = changes osmolarity of medullary space [300/400—> 350/500]
- new fluid being pushed is exposed to hyperosmotic env as it travels down = favours H2O reabsorption out of the THIN descending limb and into medullary space.
- new fluid = osmolarity of THICK ascending limb decreases = [200/400 —> 150/300]

  • THIN DL = hyperosmotic
  • THICK AL = hypo-osmotic
49
Q

The steps to change environment in medulla

STEP 6)

A

6) iso-osmotic state in DESCENDING limb; osmotic difference between descending and ascending [350/500 —> 300/150]
- new fluid pushed down fluid, slowly becoming [350/500] in the THIN DL
- the gradient for water reabsorption from THIN DL to the medullary space is now establish [350/500]

50
Q

The steps to change environment in medulla

STEP 7)

A

7) more water enters tubule, process continues. System is in ready state, the osmotic gradient has been established.
- gradient in medullary space changes after maximum number of turns —> [300/500/900/1200/1400]
- osmolarity is at 1200/1400 at the depth of tubule. 1400 = max turns

51
Q

What’s is the osmolarity of the cortex ?

A

It’s 300, it’s ALWAYS 300 and it never changes. Unlike the medullary space osmolarity which is responsible for H2O gradient

52
Q

The size of the cortex compared to the medullary interstitial space determines the

A

maximum osmolarity as well as length of the tubule.

53
Q

How does the size of the cortex determine the maximum osmolarity and length of tubule?

A

As water exits the lumen of tubule, with limited area permeability, luminal [urea] increases

Although the urea gradient opposes water reabsorption, the NaCl gradient is so large that is net effect is water reabsorption

54
Q

What cause the osmolarity in the medullary space to be 1200-1400?

A

Half is due to NaCl and half Is due to urea.

55
Q

The late Distal tubule and collecting duct being impermeable to water is the case if

A

The body is hydrated.

  • Distal tubule always at [300]
  • osmolarity of the collecting ducts is [100] throughout the entire thing = no gradient = impermeable to H2O reabsorption
56
Q

The late Distal tubule and collecting duct being permeable to water is the case if

A

The body is dehydrated = received signal to become permeable = H2O reabsorption

  • Distal tubule is always 100 —> favours H2O reabsorption from distal to cortex (not medullary)
  • collecting duct = permeable = osmolarity in both the collecting tubule and medullary space go up = HYPO-OSMOTIC = favours H2O reabsorption = GRADIENT !
57
Q

How do you tell the distal tubule or the collecting duct to become permeable to water?

A

Through the release of antidiuretic hormone (ADH) and vasopressin AVP

58
Q

Antidiuretic Hormone (ADH) (Arginine Vasopressin (AVP)) increases

A

water permeability = increases H2O reabsorption =

more fluid in blood and less in urine

59
Q

How ADH increases water permeability

A

First ADH binds to receptor on basolateral membrane = sets of cascade of events = increase the number of AQP-2 (not AQP-1 or 3 or 4) channels on the apical membrane in the distal tubule and collecting ducts. ——->

More channels = More water that moves from the tubule gets into the principle cell, then AQP-3 on the basolateral will then facilitate water moving from the cell and eventually into the peribular fluid and into the blood to be reabsorbed.

60
Q

Where is ADH released from?

A

ADH released in the brain at the hypothalamus, released by the posterior pituitary.

61
Q

What kind of receptors used for water reabsorption under ADH influence?

A
  • AQP-2 on the apical side (these the ones that are increased by ADH) takes water from distal/collecting to increase cell.

And

  • AQP-3 on the basolateral side that takes water from cell into blood
62
Q

Blood flow in the nephron is

A

countercurrent

63
Q

The Vasa Recta’s Countercurrent

Exchange Mechanism and Relatively Low Blood Flow Minimize the

A

Washout of the Medullary Hypertonicity

64
Q

KEEP GOING I LOVE YOU AND KEEP LOVING YOUR SELF CUZ

A

You amazing btich !

65
Q

How does the vasa recta maintain osmotic gradient and prevent washout?

A

Vasa recta capillaries run parallel to loops of Henle. Vasa recta slows down the blood flow which helps maintain the osmotic gradient required for water reabsoption

66
Q

Main function of the vasa recta:

A

They remove the water and solute that is continuously added to the medullary interstial space by the nephron. Maintains the osmolarity in the blood.

67
Q

Where is the vasa recta connected to ?

A

The loops of Henley, both descending and ascending

68
Q

What’s does counter current mean

A

The vasa recta and loops of henle

69
Q

What is countercurrent exchange in kidney?

A

Countercurrent multiplication in the kidneys is the process of using energy to generate an osmotic gradient that enables you to reabsorb water from the tubular fluid and produce concentrated urine.

70
Q

As the filtrate I’d entering the descending limb, it progressively is becoming

A

More concentrated as it losses water into the medullary space.

71
Q

As the as descending limb is pumping out Na,K,Cl ions inot the medullary space, the filtrate becomes more

A

hypertonic

72
Q

Blood in the vasa recta removes water leaving the

A

Loop of henle

Phsyiology 210 B (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions