Renal Transport Cont. Flashcards

1
Q

Factors that stimulate Na+ Reabsorption?

A
  • Na + deficiency

- Hyponatremia

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2
Q

Factors that stimulate Na+ Secretion?

A
  • Hypernatremia
  • Prostaglandins
  • ANP
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3
Q

If there is a problem with Na+ concentration, the problem is usually involved with?

A

Water

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4
Q

Factors that stimulate K+ Secretion?

A
  • K+ Excess

- Aldosterone

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5
Q

Factors that stimulate K+ Reabsorption?

A
  • K + deficiency

- Hypokalemia

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6
Q

What 2 things cause ADH to be released?

A
  1. Hyperosmolarity

2. Volume Depletion

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7
Q

ADH is more sensitive to small changes in?

A

Osmolality!

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8
Q

What are the 3 mechanisms of ADH?

A
  1. Increase water permeability
  2. Increase Urea permeability
  3. Increase activity of NKCC2
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9
Q

Where does ADH increase water permeability?

A

Principal cells in the distal tubule

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10
Q

How does ADH increase water permeability at principal cells in the distal tubule?

A

Inserts AQPs into apical membrane

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11
Q

Which AQP does ADH insert on to the apical membrane of principal cells in the distal tubule?

A

AQP - 2

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12
Q

Since ADH can insert AQP - 2 on to principal cells, what will this cause?

A

Water will be REABSORBED

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13
Q

Under the action of ADH, water is reabsorbed. What is left behind in the tubule?

A

UREA

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14
Q

Where in the nephron is the [urea] really HIGH?

A

Inner Medullary Collecting Duct

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15
Q

What happens when the [urea] is really high in the inner medullary collecting duct?

A

It will diffuse out passively

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16
Q

Describe how Urea is recycled under the actions of ADH

A

ADH causes more water to be reabsorbed at the distal tubule

  • This leaves Urea behind in the distal tubule with concentrations increasing
  • Once at the inner medullary collecting duct, urea will passively diffuse out of the tubule
  • Urea will then eventually diffuse back into the tubule upstream
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17
Q

ADH also increases the activity of the NKCC2 at the thick ascending limb. What does this cause?

A

More reabsorption of Na, K, 2Cl. Further, due to back leak of K+ this indirectly causes more reabsorption of Mg and Ca!

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18
Q

Where is the Kidney Interstitium and what does it contain?

A

Between tubules and vessels

- contains Interstitial fluid, ECM and cells

19
Q

As you move from the Kidney’s cortex, to outer medulla, to inner medulla, what increases?

A

Interstitium Osmolality!

20
Q

The kidney interstitium osmolality increases as you move towards?

A

Inner medulla

21
Q

What 2 mechanisms control urine concentration?

A
  1. Counter Current Multiplier

2. Counter Current Exchanger

22
Q

With the Counter Current Multiplier, what leaves the Ascending limb and enters the kidney interstitium?

A

NaCl

23
Q

With the Counter Current Multiplier, as NaCl enters the interstitium, what does this cause to happen to the interstitium?

A

It becomes hyperosmotic

24
Q

With the Counter Current Multiplier, as NaCl enters the interstitium, what will leave the Descending limb?

A

Water

25
Q

With the Counter Current Multiplier, as water enters the interstitum, what does this cause to happen to the hyperosmotic interstitium (due to NaCl from ascending limb)?

A

Equalizes the osmolality

26
Q

With the Counter Current Multiplier, as more fluid enters the descending limb, what will this create?

A

A gradient

27
Q

The length of the loop of Henle determines?

A

SIZE OF GRADIENT

28
Q

What determines the size of the gradient?

A

Length of the loop of Henle

29
Q

After the Counter Current Multiplier, then what occurs?

A

Counter Current Exchanger

30
Q

With the Counter Current Exchanger, water has entered the interstitial fluid from the Descending limb. Where does it get reabsorbed?

A

Vasa Recta

31
Q

The medullary osmolality is due to what 2 molecules?

A

NaCl

Urea

32
Q

This vessel minimizes solute washout from interstitium

A

Vasa Recta

33
Q

What is Osmolar Clearance?

A

Total clearance of ALL solutes from the blood

34
Q

What is the equation for Osmolar Clearance?

A

U * V/(P) – same as renal clearance but for all solutes

35
Q

What is Free Water Clearance?

A

The rate at which the body excretes SOLUTE - FREE WATER

36
Q

What is the equation for Free Water Clearance?

A

V - Cosm

37
Q

If Free Water Clearance is (+), what does that mean?

A

FREE WATER WAS EXCRETED

38
Q

If Free Water Clearance is (-), what does that mean?

A

More solutes than free water were excreted

39
Q

What is the Obligatory Urine Volume (OUV)?

A

Minimum amount of urine required to secrete waste products

40
Q

What is the equation for Obligatory Urine Volume?

A

Minimum solute excretion per day/Maximum urine concentrating ability

41
Q

Continuously reabsorb solutes and NOT water

excreting lots of water

A

Diurersis

- High volume and dilute urine

42
Q

Requires high ADH and high Osmolality of interstitial fluid (water reabsorption)

A

Antidiuresis

43
Q

Excretion of large amounts of Na+

A

Natriuresis