Renal physiology (Latin renes, "kidneys") is the study of the physiology of the kidney. This encompasses all functions of the kidney, including maintenance of acid-base balance; regulation of fluid balance; regulation of sodium, potassium, and other electrolytes; filtering toxins, absorption glucose, amino acids, and other small molecules; regulation of blood pressure; the production of various hormones including erythropoietin, and the activation of vitamin D.