Regulation of Extracellular Fluid Potassium Concentration and Potassium Excretion

Flashcards covering essential vocabulary related to potassium regulation and homeostasis.

Extracellular fluid potassium concentration

Normally regulated at about 4.2 mEq/L, rarely fluctuating more than ±0.3 mEq/L.

Hyperkalemia

A life-threatening condition characterized by increased plasma potassium concentration.

Hypokalemia

A condition resulting from low plasma potassium concentration.

Potassium excretion

Primarily regulated by the kidneys, crucial for maintaining potassium balance.

Aldosterone

A hormone that increases potassium uptake into cells and regulates potassium balance.

Insulin

Stimulates sodium-potassium ATPase activity, promoting potassium uptake into cells post-meal.

Acidosis

A condition that may enhance extracellular potassium concentration.

Alkalosis

A state that can lead to decreased extracellular fluid potassium concentration.

Cell lysis

A process that releases potassium into extracellular fluid, potentially causing hyperkalemia.

Renal potassium excretion determination

Calculated as the sum of filtered load, reabsorption and secretion rates.

Principal cells

Cells in the distal tubules and collecting ducts that are critical for potassium secretion.

Na+-K+ ATPase pump

Transport protein that facilitates potassium uptake from the interstitial fluid into the tubular cells.

H+ secretion

The process by which excess hydrogen ions are excreted from the body, influencing potassium handling.

Ammonium ion (NH4+)

A form of nitrogen that is crucial in the tubular secretion of H+ during acidosis.

Bicarbonate buffering

A major system that helps maintain pH balance in kidney function and extracellular fluid.

Causes of hyperkalemia

Includes renal failure, medications, and excessive dietary intake.

Causes of hypokalemia

May result from excessive vomiting, diarrhea, or diuretic use.

Potassium homeostasis

Maintained by dietary intake, excretion, and shifts between intracellular and extracellular compartments.