Editing Homeostasis (section)

===Potassium concentration===
{{Main |Potassium#Homeostasis |Potassium in biology}}
High potassium concentrations in the plasma cause [[depolarization]] of the [[zona glomerulosa]] cells' membranes in the outer layer of the [[adrenal cortex]].<ref name="pmid22546854">{{cite journal |vauthors=Hu C, Rusin CG, Tan Z, Guagliardo NA, Barrett PQ |title=Zona glomerulosa cells of the mouse adrenal cortex are intrinsic electrical oscillators. |journal=J Clin Invest |volume=122 |issue=6 |pages=2046–2053 |date=June 2012 |pmid=22546854 |doi=10.1172/JCI61996 |pmc=3966877}}</ref> This causes the release of [[aldosterone]] into the blood.

Aldosterone acts primarily on the [[distal convoluted tubule]]s and [[collecting duct]]s of the kidneys, stimulating the excretion of potassium ions into the urine.<ref name=tortora3 /> It does so, however, by activating the [[basolateral]] [[Na+/K+-ATPase|Na<sup>+</sup>/K<sup>+</sup> pumps]] of the tubular epithelial cells. These sodium/potassium exchangers pump three sodium ions out of the cell, into the interstitial fluid and two potassium ions into the cell from the interstitial fluid. This creates an [[electrochemical gradient#Ion gradients|ionic concentration gradient]] which results in the reabsorption of sodium (Na<sup>+</sup>) ions from the tubular fluid into the blood, and secreting potassium (K<sup>+</sup>) ions from the blood into the urine (lumen of collecting duct).<ref name="pmid10760062">{{cite journal|year=2000|last1=Palmer|first1=LG|last2=Frindt|first2=G|title=Aldosterone and potassium secretion by the cortical collecting duct|journal=Kidney International|volume=57|issue=4|pages=1324–8|pmid=10760062|doi=10.1046/j.1523-1755.2000.00970.x|doi-access=free}}</ref><ref>{{cite journal |vauthors=Linas SL, Peterson LN, Anderson RJ, Aisenbrey GA, Simon FR, Berl T |title=Mechanism of renal potassium conservation in the rat |journal=Kidney International |volume=15 |issue=6 |pages=601–11 |date=June 1979 |pmid=222934 |doi= 10.1038/ki.1979.79|doi-access=free }}</ref>