A tale of two kidneys

Abstract

Little has changed in our basic physiological understanding of the kidneys in the last 70 years. Indeed, the renal system functions to maintain acid-base homeostasis, eliminate detoxified substances, and regulate the plasma ion concentration and volume in response to endogenous or exogenous stimuli.^1–3 The by-product of these processes is the production of urine, the composition of which changes according to the physiological needs of the individual. Additionally, the kidneys also produce hormones such as renin, erythropoietin, and the active form of vitamin D.⁴

This article serves as a summary of some important concepts that occur relating to renal function: tubuloglomerular feedback, ion exchange in the nephron, and the countercurrent multiplier and exchange systems.