Renal Transport Mechanisms - Pierce Flashcards

1
Q

Proximal convoluted tubule reabsorbs what
100%
mostly
very little

A

glucose + aa = 100%
Na, K, P, Ca, H2O = 70%
only 30% Mg

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2
Q

where is most of the Mg reabsorbed

A

thick ascending limb (also Distal straight tubule)

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3
Q

how do solutes get reabsorbed (order of layers crossed)

A
  1. apical membrane of tubule
  2. Basolateral membrane of tubule
  3. epithelium of BV
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4
Q

where can you find the brush border

A

apical side facing lumen of tubule

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5
Q

things that cross apical side of PT

not H2O

A
  1. Na/glucose (SGLT)
  2. Na/ aa
  3. NA/ HCO-3
  4. Na/ H+ (antiport) (NHE)
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6
Q

things that cross basolateral side of PT

not H2O

A
  1. Na/K+ ATPase

2. HCO-, aa, glucose (GLUT), H+ , Cl- all diffuse over to BV

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7
Q

which BV is around the PT

A

peritubular capillary

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8
Q

how does water cross the PT

A

passive transport by AQP channel on both apical and basolateral
enters BV by bulk flow

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9
Q

when reabsorbing H2O

A

NA always follows

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10
Q

which part of the LOH is h2o permeable

A

the thin LOH (think ascending and thin descending)

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11
Q

Thick Ascending Limb (TAL) reabsorption of what

A

X WATER

  1. Na,
  2. K
  3. Ca
  4. Mg *
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12
Q

TAL reabsorption on apical side

A
  1. NKCC2 channel (Na-K-2Cl)

2. ROMK (EXCRETE K+ back to urine)

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13
Q

TAL reabsorption on basolateral side

A
  1. Mg+, Ca paracellulary
  2. Na/K ATPase
  3. Cl- channel
  4. K+ channel
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14
Q

what is the role of ROMK

A

back leak of K+ into the urine (lumen) which bulids up gradient and helps Mg and Ca paracellulary leave

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15
Q

Distal convoluted tubule reabsorption + role

A
minimal reabsorption (X WATER)
MAINTAIN REGULATION site
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16
Q

ADH and Aldosterone act on what

A

principal cells of Distal convoluted tubule

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17
Q

3 cell types of DCT

A
  1. principal cells
  2. a- intercalated cells
  3. B-intercalated cells
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18
Q

principal cells role

A

REAB : Na+, H2O

SECRETE: K+

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19
Q

a- intercalated cell role

A

REAB : K+, HCO-3

SECRETE: H+

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20
Q

B- intercalated cell role

A

REAB : H+, Cl-

SECRETE: K+, HCO-3

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21
Q

DCT uses what to reabsorb at apical end

A
  1. NCC (Na, Cl-) thiazide-sensitive
  2. TRPV5 (ligand Ca+2 channel)
  3. ENaC (Na, H2O)
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22
Q

DCT uses what to reabsorb at basal end

A
  1. Cl- channel
  2. Na/K+ ATPase
  3. NCE (Ca+ out to BV and Na+ into cell)
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23
Q

principal cells use what to reabsorb Na+ and H2O

apical

A

ENaC on apical side

*where aldosterone binds to

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24
Q

principal cells use what to reabsorb Na+ and H2O

basolateral

A

Na/K ATPase

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25
Q

principal cells use what to secrete K+

A

ROMK + BK, when Na+ is reabsorbed by ENaC

26
Q

B-intercalated cells use what on apical side

A
  1. HCO-3/Cl- (HCO-3 to urine, Cl- reab)

2. K+ leak channel

27
Q

B-intercalated cells use what on basal side

A
  1. Cl- channel

2. H+/K+ ATPase channel (H+ to BV, K+ to cell)

28
Q

a-intercalated cells use what on apical side

A
  1. H/K ATPase (K into cell, H to urine)

2. Cl- channel

29
Q

a-intercalated cells use what on basal side

A
  1. K+ leak channel

2. HCO-3/Cl- (HCO-3 to BV, Cl- into cell)

30
Q

4 things causing NA reabsorption

A
  1. NA deficiency
  2. Hyponatremia
  3. severe diarrhea (loss of NA)
  4. too much H2O (normal Na levels however very dilute)
31
Q

2 things causing NA secretion

A
  1. hypernatremia

2. ANP

32
Q

salt deficiency what happens in steps

what kind of urine will you have

A
DIURESIS
1. decrease ADH (to increase osmo of envir)
2. more water will be excreted
3. decrease in BP and Blood Volume 
4. Renin and NA reab.
= hypotonic urine
33
Q

salt excess what happens in steps

what kind of urine will you have

A
ANTI- DIURESIS
1. increase ADH (to dilute Envir)
2. increase water reab
3. increase BP and Blood volume
4. stimulate ANP
5. inhibit aldosterone = no na+ reab
= hypertonic urine
34
Q

what 2 things cause K+ secretion

A
  1. Aldosterone

2. increased K+ in serum (nothing to do with water amount)

35
Q

where is most K+ reab

A

PT

36
Q

where is most K+ secreted

A

CD

37
Q

what 3 things cause K+ reabsorption

A
  1. severe diarrhea (K+ loss)
  2. K+ deficiency
  3. Hypokalemia
38
Q

ADH is sensitive to what

A

changes in osmolality

not Blood volume

39
Q

what gets activated to activate ADH

A
  1. Osmoreceptors : hypothalamus and liver

2. Baroreceptors : aortic and carotid sinus

40
Q

dail recommended Na intake``

A

500mg/dl

41
Q

3 roles of ADH

A
  1. act on principal cell AQP2 to reab H2O
  2. increase Urea reab. to interstitium (inner medulla CD)
  3. increase NKCC2 on TAL (reab Na, Cl, K) + K+ backleak(Mg, Ca)
42
Q

how does ADH cause Urea diffusion out of tubule

A

more h2o is reabsorbed the father you get down the CD = urea builds up and then diffuses out
—-> goes to LOH to be secreted*
= makes medulla salty during high NA in blood

43
Q

the longer the LOH and CD

A

the more concentrated the bottom can get (up to 1200 in humans)

44
Q

countercurrent exchange

A

NaCl leaves Ascending LOH
H2O leave Descending LOH
= the NaCl causes the interstitium to get more and more salty and the BV cant pick up as much moving down (also getting more and more salty)
= the h2o is reab on the way up diluting the interstitium and BV

45
Q

BV involved in LOH

A

vasa recta

46
Q

what impacts CC exchange

A

BF rate (going in opposite direction) needs time to pick up Na and H2O

47
Q

Countercurrent Multiplication

A

NaCl leaves Ascending LOH
H2O leave Descending LOH
= new fluid is continuously put into descending LOH, increasing H2O diffusion out as it travels down( concentrated urine)
= Na+ keeps getting reab on the way up to dilute urine

48
Q

what 2 things determine how salty the medulla can get

A
  1. BF rate

2. the length of the LOH

49
Q

what prevents the medullary high osmolality from disappearing

A

the vasa recta

50
Q

what will a vasodilator or increased arterial P do

A

both increase BF rate through the kidney = the urine will not get as concentrated at the most inner medulla

51
Q

osmolar clearance

what is it and how to calculate it

A

how to clear all of a solute from blood

Cosm = (Uosm x V) / (Posm)

52
Q

free water clearance

what is it and how to calculate it

A

how fast the body excretes water with NO solutes in it
Ch2o = V - Cosm
V = urine flow rate

53
Q

free water clearance is -

free water clearance is +

A
  1. excess solutes in urine (conserving water)

2. excess h2o in urine (dilulte)

54
Q

Obligatory urine volume is calculated how

A
OUV = (minimum solute you need to excrete) / Max urine concentration ability
OUV = 600/ 1200
OUV = 0.5L / day of urine (to not have excess solute build up)
55
Q

minimum solute you need to excrete per day for the average person and their diet

A

600mOsm/ day

56
Q

reason drinking sea water makes you dehydrated even more

A
  1. you are ingesting 1800mOsm if you drink 1L
  2. OUV = 1800/ 1200
    OUV = 1.5 L per day
  3. you did not even drink that much
  4. body takes water from cells to excrete all the solutes and make 1.5L
57
Q

Diuresis is what

A

REAB SOULTES

EXCRETE H2O

58
Q

Anti-diuresis requires what

A
  1. high ADH (body needs water)

2. high osmolality in renal medulla INTERSTITIAL FLUID (medulla is too hyperosmolalitied)

59
Q

what 2 things makes the medulla salty

A
  1. NaCl

2. Urea

60
Q

Natriuresis
what is it
what 3 things causes it

A

LARGE NA+ EXCRETION that is NOT preportional to amount of H2O excreted

  1. Drug
  2. H (ANP)
  3. high renal perfusion pressure = Na+ doesn’t have time to get reabsorbed