ABSTRACT
Introduction The prime function of the kidney is to assist with the maintenance of the internal environment through the control of four broad physiological functions: (1) the selective control of the elimination or retention of water, (2) the selective control of the elimination or retention of electrolytes and other solutes, (3) maintenance of pH homeostasis and (4) hormone production. The first three of these functions occur through the combination of glomerular ultrafiltration, tubular reabsorption and active secretion along the length of the nephron, leading to the excretion of urine, whereas a number of hormonal processes, most notably erythropoietin (EPO) production and the activation of vitamin D, occur away from the glomerular and tubular apparatus.
