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Renal Exam 2 > K+ Regulation > Flashcards

K+ Regulation Flashcards

1
Q
  • Normal serum K+
A

3.5-5.0 mEq/L

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2
Q
  • Role of epinephrine in the regulation of K+
A
  • Lowers serum K+ by uptake into cells of extrarenal tissues
  • Stimulates K+ excretion in the kidney
  • Differing response for alpha versus beta stimulation
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3
Q
  • Role of insulin in the regulation of K+
A
  • Stimulates Na+/K+ ATPase causing a flux of K+ into cells and efflux of Na+ out of cells
  • Can be used with glucose to treat hyperkalemia
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4
Q
  • Role of aldosterone in regulation of K+
A
  • Renal: Increase in K+ excretion
  • Extrarenal: INcreased K+ secretion into intestinal fluids and saliva
  • Enhances acid secretion via production of systemic alkalosis
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5
Q
  • Hypokalemia is associated with which change in acid base balance?
A

HypOkalemia is associated with AlkaLOSIS

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6
Q
  • Insulin efect on K+
  • Mechanism
A
  • Enhanced cell uptake
  • Na+/K+ ATPase
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7
Q
  • Beta catecholamines effect on potassium
  • Brief mechanism
A
  • Enhanced cell uptake
  • Increased activity of the Na+/K+ ATPase via increased activation of cAMP
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8
Q
  • Alpha catecholamine effect on K+
  • Brief mechanism
A
  • IMPAIRED cell uptake
  • Decreasing activity of the Na+/K+ ATPase via inhibition of cAMP
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9
Q
  • Acidosis effects on K+
  • Brief mechanism
A
  • IMPAIRED cell uptake
  • Donnan effect;inhibition of the Na+/K+ ATPase
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10
Q
  • Alkalosis effects on K+
  • Mechanism
A
  • Enhanced cell uptake
  • “k is lo” alkalosis
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11
Q
  • External K+ balance effect on K+
  • Mechanism
A
  • Loose correlation
  • Ratio vs total body K+ until severe states
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12
Q
  • Hyperosmolarity effect on K+
  • Mechanism
A
  • Enhanced cell efflux
  • D/t contraction of ICF volume and increased intracellular [K+]
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13
Q
  • Strenous exercise effect on K+
  • Mechanism
A
  • Enhanced cell efflux
    *
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14
Q
  • Insulin and catecholamines activate which transporters? (MORE THAN ONE!)
A
  • Na+/K+ ATase
  • Na+/H+ Exchanger
  • NKCC
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15
Q
  • FIltered load of K+
A

Filtered load= GFR x [X]plasma x % filterability

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16
Q
  • What things are reabsorbed in the proximal tubule?
  • What things are excreted into the proximal tubule?
  • Major mechanism for reabsorption of K+?
A
  • Na+, Cl-, Glucose, Amino Acids, H2O, K+, Bicarb
  • H+, Organic acids, bases
  • Na+/K+ ATPase of the basolateral membrane
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17
Q
  • Changing _ reabsorption has considerable effevts on distal tubular _ and _ delivery, which impacts K+ later on
A
  • NaCl
  • Flow
  • Na+
18
Q
  • What drives K+ reabsorption in the PT?
A
  • Lumen positive transepithelial difference (TEPD)
19
Q
  • How does TEPD work in the transepithelial tubule?
A
  • In early PT, Na+ is reabsorbed primarily with HCO3-
  • Cl- gets left behind
  • Negative TEPD builds up
  • Cl- is repelled and reabsorbed
  • Positive TEPD builds up as Cl- is reabsorbed
  • Positive TEPD repels K+
  • K+ is reabsorbed paracellularly
20
Q
  • How does LOH trabnsport and medullary recycling of K+ occur?
A
  • K+ secreted into cortical collecting duct
  • K+ is reabsorbed by the outer medullary collecting duct and innner medullary collecting duct
  • K+ floats into the interstitium
  • K+ is secreted into late Proximal tubule/Descending thin limbs of the LOH
21
Q

Goal of medullary K+ recycling

A
  • Increase presence of medullary KC
  • Large K+ presence decreases NKCC2 reabsorption by thick ascending limb
  • Enhanced Na+ delivery to the distal tubule
  • Stimulates Na+ reabsorption and K+ secretion
  • Helps you excrete K+ during dietary loading
22
Q
  • K+ is secreted or reabsorbed in _ according to the needs of the body
A
  • Late distal tubule and cortical collecting duct
23
Q
  • What types of cells secrete K+?
A
  • Principal cells
  • Beta intercalated cells
24
Q
  • Most important factors stimulating K+ secretion
A
  • Increased ECF [K+]
  • Aldosterone
  • Increased tubular flow rate
25
Q
  • What types of cells reabsorb K+
A
  • Alpha intercalated cells
26
Q
  • Function of principal cells
A
  • Reabsorb: Na+, H2O
  • Secrete: K+
27
Q
  • Function of alpha intercalated cells
A
  • Reabsorb K+ and HCO3-
  • Secrete H+
28
Q
  • Function of beta intercalated cells
A
  • Reabsorb H+ and Cl-
  • Secrete K+ and HCO3-
29
Q
  • Major factors regulating K+ secretion (buildup of extracellular [K+])
A
  • Na+/K+ ATPase activity on basolateral membrane is increased
  • Reduced back leakage of K+ from ICF to renal interstitium,
  • Increased synthesis of K+ channels and instertion into the luminal membrane
  • Increased aldosterone secretion
  • Increased distal tubular flow rate
30
Q
  • _ is important in helping to preserve normal K+ excretion during changes in Na+ intake and aldosterone levels
A
  • Increased tubular flow rate
31
Q
  • Define alkalosis
A
  • Decrease in H+ ion concentration in the ECF
32
Q
  • Define alkalemia
A
  • Physiologically high blood pH
33
Q
  • Define acidosis
A
  • Acute process that increases H+ ion concentration in the ECF
34
Q
  • Define acidemia
A
  • Physiologically low blood pH
35
Q
  • What occurs physiologically during acute alkalosis
A
  • Increased activity of the Na+/K+ ATPase pump
  • Increased [K+]i
  • Increased passive diffusion of K+ into tubule lumen
  • Increase in K+ channels
  • Increase in K+ secretion
  • End result=hypokalemia (k+ is lo)
36
Q
  • What occurs physiologically during acute acidosis?
A
  • Decreased activity of the Na+/K+ ATPase
  • Decreased [K+]i
  • Decreased passive diffusion of K+ into tubule lumen
  • Decrease in K+ channels on apical membrane?
  • Decrease in K+ secretion
  • End result=hyperkalemia
37
Q
  • What is the key difference between acute v chronic acidosis?
A
  • Chronic acidosis stimulates K+ secretion
  • Why?
    • Chronic metabolic acidosis decreases reabsorption of water and solutes from PCT by inhibiting Na+/K+ ATPase
    • Increased tubular flow to DT and CD
    • RAAS is stimulated d/t lack of water reabsorption and decrease in ECF volume
    • K+ secretion increases
38
Q
  • What factors increase K+ secretion
A

ADH

Luminal flow rate

Alkalosis

Glucocorticoids

Anion Delivery

39
Q
  • What factors decrease K+ secretion
A
  • Acidosis
40
Q
  • Diuretics that inhibit Na+ reabsorption willl promote K+ _
A
  • secretion

Renal Exam 2 (8 decks)

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