Questions i got wrong Flashcards
(14 cards)
Briefly explain how aldosterone affects potassium secretion in the collecting duct.
Aldosterone stimulates Na⁺ reabsorption via ENaC and increases K⁺ secretion by increasing ATPase activity and luminal K⁺ channel permeability, promoting K⁺ movement into the lumen.
How does insulin affect plasma potassium levels?
Insulin promotes potassium uptake into cells by stimulating Na⁺-K⁺-ATPase, lowering plasma [K⁺].
Why does loop diuretic use increase the risk of hypokalaemia?
Loop diuretics block the Na⁺-K⁺-2Cl⁻ symporter, leading to less reabsorption of K⁺ and increased distal flow, which enhances K⁺ secretion and loss.
What is the effect of acute metabolic acidosis on renal potassium handling?
Decreases potassium secretion
Which cells reabsorb potassium during severe hypokalaemia?
Intercalated cells
What is the role of intercalated cells in the collecting duct?
Maintain acid-base balance by secreting H⁺ or reabsorbing HCO₃⁻.
What is the correct formula for estimating plasma osmolarity (in mmol/L)?
D. 2[Na⁺] + [K⁺] + [Glucose] + [Urea]
Role of macula densa?
Macula densa senses low Na⁺ → signals juxtaglomerular cells → renin release → RAAS activation → vasoconstriction and increased Na⁺ reabsorption.
What ratio of bicarbonate to carbon dioxide is typically found in plasma for effective buffering?
20:1
