Term
| What areas of the nephron regulate potassium levels? |
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Definition
PCT: Bulk Flow Resorption
Thick Ascending: Na-K-Cl Absorption with partial leakage
Collecting Ducts: K Secretion |
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Term
| What is the mechanism of K secretion in the Principal Cells? And what factors can alter the amount of secretion? |
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Definition
Na/K-ATPase Basally
K Channels on the Lumen Side
Factors: Flow Rate, Amount of Sodium reaching Principal Cells, pH, Aldosterone |
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Term
| What are the mechanisms of aldosterone that favor K secretion? |
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Definition
Increase Na/K ATPase Activity
Increase ENaC Channel for Sodium
Increase K channels on the lumenal side |
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Term
| What stimuli will temporarily shift potassium into the intracellular space? |
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Definition
Insulin
Beta-Agonists
Refeeding (By generating more cytoplasm)
Alkalemia |
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Term
| What are the signs of Hyperkalemia and what are the signs of Hypokalemia? |
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Definition
Hypo: Muscle Weakness and EKG U wave
Hyper: EKG-Spiked T waves, Wide QRS |
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Term
| What are the major reasons for potassium loss and what is the mechanism of each? |
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Definition
Diarrhea
Vomiting: Direct loss in vomit and Alkalosis from acid loss-> more bicarb at the principal cells-> K secretion
Diuretics: More Na @ Principal-> K secretion
Hyperaldosteronism
Renal Toxicity: Amphotericin, Aminoglycoside
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Term
| How do you discern the source of potassium loss? |
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Definition
| Check Urine Potassium, if high, the hypokalemia is a renal regulatory problem |
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Term
| What are some causes of insufficient excretion of Potassium? |
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Definition
Acute Renal Failure
NSAIDS used in impaired kidneys
Adrenal Insufficiency
K-Sparing Diuretics |
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Term
| What factors would cause a shift of potassium out of cells leading to Hyperkalemia? |
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Definition
B-blockage
Cell Injury
Acidosis
Hyperglycemia |
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Term
| What is the treatment for hyperkalemia? |
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Definition
Ca Infusion: Stabilize heart
Insulin+Glucose
B-Agonist
Kalexelate: Trades Na for K |
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Term
| Under what conditions can drugs such as Spironolactone, Ace Inhibitors, Heparin, NSAIDS, B-Blockers cause serious Hyperkalemia? |
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Definition
| When the kidney has already been insulted |
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Term
| When is Hypokalemia an urgent situation? |
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Definition
Below 3mEq/L
Digitalis or Ischemia Induced |
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Term
| Why would you expect a uncontrolled diabetic to exhibit hyperkalemia |
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Definition
| low insulin levels and hyperglycemia favor potassium leakages from cells into the Extracellular fluid |
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