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Renal > Renal part 3 for final > Flashcards

Renal part 3 for final Flashcards

0
Q

Changes in extracellular K+ can impact what?

A

resting membrane potential

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1
Q

What percent of total body K+ is intracellular?

A

98%

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2
Q

Increase in extracellular K+ does what?

A

decrease resting membrane potential–>increase excitability

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3
Q

What is the total extracellular fluid K+ content?

What does this mean?

A

~56mEq (14L X 4mEq/L)

Ingestion of small amounts of K+ from the GI tract could have significant effects on plasma conc. if retained within the ECF

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4
Q

How are dietary induced changes in [plasma K+] prevented?

A

RAPID cellular uptake of K+
(epinephrine, insulin, aldosterone->increase Na+K+ATPase)

SLOWER renal excretion

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5
Q

‘obligatory’ reabsorption of ~90% of the filtered load of K+ occurs where?

A

proximal tubule

thick ascending limb

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6
Q

If only 10% of filtered load K+ if delivered to the distal nephron, why is there higher filtered load percentages excreted in the urine?

A

Because K+ is SECRETED into the late distal and collecting tubule

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7
Q

How is K+ typically secreted into the distal and collecting tubule?

A

Uptake across basolateral membrane via Na+K+ATPase

Efflux across luminal membrane via: K+ channels and K+Cl- cotransp.

Na+ reabsorption creates lumen-negative potential which also promotes K+ secretion

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8
Q

What occurs in K+ depletion?

A

K+ secretion ceases and K+ reabsorption increases

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9
Q

Mechanism for K+ reabsorption during a state of K+ depletion.

A

Uptake across luminal membrane via energy-depend. K+H+ anti-porter
Efflux across basolateral membrane via K+selective channels

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10
Q

Hypertonic ECF causing the cell to shrink results in what?

regarding [K+]

A

Increases intracellular [K+] causing increase K+ efflux resulting
in hyperkalemia

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11
Q

What is the result of cell lysis releasing K+ into the ECF?

Whats an example that causes this phenomenon?

A

local hyperkalemia

Exercise-induced muscle breakdown

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12
Q

Metabolic alkalosis (decrease ECF H+) = ___plasma K+

A

decrease

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13
Q

Metabolic acidosis (increase ECF H+) = ___plasma K+

A

increase

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14
Q

How is plasma K+ effected from metabolic acidosis due to inorganic acids VS organic acids

A

Metabolic acidosis due to inorganic acids (HCl,H2SO4) increases plasma K+ to a much greater extent than organic acids (lactic acid, keto acids)

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15
Q

Do respiratory acid-base disorders have effect on plasma K+?

A

no

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16
Q

Increases in ECF [K+] increases K+ secretion and thus increases urine K+ excretion by what methods?

A

Directly increase Na+K+ATPase activity on the DISTAL nephron cells

Directly increase aldosterone secretion: Inc. Na+K+ATPase activity
Inc. luminal memb. K+ permeability

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17
Q

Increase in tubular flow does what to K+ secretion?

A

Increases

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18
Q

Extended use of loop diuretics does what?

A

increases K+ excretion and can lead to hypokalemia

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19
Q

Maintenance of normal plasma Ca2+ is dependent on what hormone?

A

parathyroid hormone

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20
Q

Where does PTH stimulate Ca2+ reabsorption in the kidney? And whats being stimulated there?

A

distal tubule

Ca2+ ATPase
Na+Ca2+ exchanger on the basolateral membrane

21
Q

Maintenance of normal plasma Ca2+ is dependent on parathyroid hormone-mediated effects on what?

A

kidney
GI tract
bone

22
Q

Resorption of bone releases what?

What could this potentially cause?

A

HPO4 2-

hyperphosphatemia

23
Q

how is hyperphosphatemia prevented?

A

inhibitory effects of PTH on renal HPO4 2- reabsorption

24
Q

An increase in PTH does what to HPO4 2- in the PROXIMAL tubule?

A

Decrease HPO4 2- reabsorption in the proximal tubule due to the inhibition of Na+-HPO4 2- co-transporter on the LUMINAL membrane

25
Q

What are the 3 “lines of defense” that help prevent fixed acid-induced acidification of body fluids?

A 
Physicochemical buffering
Respiratory compensation (CO2 elimination)
Renal compensation (H+ excretion; generation of HCO3-)
26
Q

What is the “isohydric” principle?

A

The combined effect of ALL buffers in a given compartment determine the free [H+] (pH)

27
Q

What is the most important extracellular buffer system? Why?

A

HCO3/CO2

lungs regulate CO2 levels
kidneys regulate plasma [HCO3-]

28
Q

Where do red blood cells transport CO2?

A

from tissues to lungs (for elimination)

29
Q

what is “chloride shift”

A

HCO3- diffuses out of the rbc in exchange for Cl-

30
Q

what is H+ buffered by?

A

de-oxygenated hemoglobin

31
Q

Where is the chloride shift process reversed?

A

at the lungs

32
Q

Under normal conditions, what controls arterial pCO2?

A

alveolar ventilation

33
Q

What is alveolar ventilation regulated by?

A

arterial pCO2

plasma [H+]

34
Q

Where is more than 99% of filtered HCO3- reabsorbed?

A

proximal tubule

35
Q

In the proximal tubule, is the reabsorptive process of HCO3- direct or indirect? Why?

A

indirect since HCO3- transport proteins are not present on the luminal membrane

36
Q

an increase in pCO2 arterial blood does what to HCO3- reabsorption?

A

increases

37
Q

an increase in Na+ reabsorption does what to HCO3- reabsorption?

A

increases

38
Q

Where does renal generation of new bicarbonate predominantly occur?

A

DISTAL nephron…intercalated collecting tubule cells

39
Q

What is the generation of NEW HCO3- dependent upon?

A

the availability of urinary buffers to accept secreted H+

“titratable acid” (HPO4 2-/H2PO4-)

40
Q

Where can HCO3- be generated from?

A

glutamine metabolism in the proximal tubule

41
Q

What hormone regulates HCO3 synthesis?

A

Aldosterone

42
Q

What state increases glutamine metabolism and thus

HCO3 synthesis/NH3 availability?

A

metabolic acidosis

43
Q

Acidemia has a blood pH of what?

A

<7.45

44
Q

Respiratory disturbances involve renal compensatory responses at what type of pace?

A

relatively slow

45
Q

What is the mechanism to restore plasma [HCO3] to normal?

24 mEq/L

A

Reabsorb ALL filtered HCO3

Generate NEW HCO3

46
Q

What is normal plasma [HCO3]?

A

24 mEq/L

47
Q

What is normal pCO2?

A

40 mmHg

48
Q

If pCO2 < 40mmHg, what is the diagnosis? What compensates?

A

RESPIRATORY acidosis

Renal compensation

49
Q

If [HCO3] is <24 mEq/L, what is the diagnosis? What compensates?

A

METABOLIC acidosis

Respiratory compensates

50
Q

If arterial pH > 7.4 due to [HCO3]> mEq/L, what is the diagnosis? What compensates?

A

Metabolic alkalosis

Respiratory compensation

51
Q

If arterial pH is >7.4 due to pCO2<40mmHg, what is the diagnosis? What compensates?

A

Respiratory alkalosis

Renal compensation

Renal (3 decks)

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