Renal Regulation of Ions Flashcards
Increase in extracellular potassium stimulates….
Increase in aldosterone secretion
What is the normal intracellular concentration of potassium ion?
140 mEQ/L
Reabsorption of potassium ion occurs where?
Proximal tubule and the ascending limb of Henle
Where does secretion potassium occur?
In the late tubule and collecting duct
What stimulates secretion of potassium by principal cells?
Potassium concentration and aldosterone
Where are principal cells found?
Late distal tubule and cortical collecting tubules
What causes large changes in aldosterone secretion?
Small changes in potassium concentration
What secretes aldosterone?
Adrenals
What does increased sodium intake cause?
decrease in aldosterone secretion and therefore potassium excretion
However, increased sodium intake also increases GFR and decreases proximal tubular reabsorption of sodium
What decreases calcium excretion?
Increased levels of PTH, plasma concentration of phosphate and metabolic acidosis
What stimulates the uptake of potassium by cells?
Aldosterone and insulin
What does hypokalemia result from?
Excess secretion of aldosterone (Conn’s syndrome)
What does hyperkalemia result from?
Deficiency in aldosterone secretion (Addison’s disease)
How much calcium is reabsorbed by the kidney?
Almost all of the filtered calcium is reabsorbed
