Chapter 2 Acid-Base/Potassium Flashcards Preview

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Flashcards in Chapter 2 Acid-Base/Potassium Deck (9)
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What percentage of filtered bicarbonate is resorbed in the proximal tubule?

80 - 85% of filtered bicarbonate is resorbed in the proximal tubule.

*Distal bicarbonate resorption is small but can increase in disorders of the proximal tubule.


What transporter is used in acute metabolic acidosis?

The sodium-bicarbonate transporter NBC-1 is recruited into the basolateral membrane to enhance bicarbonate resorption in acute metabolic acidosis.


What happens to NBC-1 in metabolic alkalosis?

The NBC-1 transporter is redistributed to the cytoplasm in metabolic alkalosis, thereby reducing bicarbonate resorption.


What happens to NBC-1 in respiratory acidosis?

NBC-1 protein synthesis is unregulated in respiratory acidosis.


Where does H+ secretion occur?

Secretion of hydrogen ions occurs predominantly in the late distal tubule, connecting segment and collecting tubules.


What four factors are necessary for optimal secretion of hydrogen ions and potassium?

1. Adequate sodium delivery to the distal nephron
2. Presence of aldosterone
3. Intact ENaC
4. Good urine flow


What is the substrate for ammoniagenesis?

Glutamine is the substrate for ammoniagenesis.


What two factors stimulate ammoniagenesis?

1. Metabolic acidosis
2. Hypokalaemia


What should lead you to suspect renal tubular acidosis?

1. Non-anion gap metabolic acidosis
2. Positive urine anion gap
3. Urine osmolality gap < 150 mEq/kg