A&P Urinary System Practice Exam – Prep, Questions & Study Guide

The kidneys play a vital role in maintaining acid-base balance in the body primarily through the mechanisms of reabsorption and secretion. The correct answer highlights that during states of acidosis (when the pH of the blood becomes too low), the kidneys excrete hydrogen ions into the urine and retain bicarbonate ions in the bloodstream.

When the body is in an acidic state, the increased concentration of hydrogen ions needs to be counteracted. To do this, the kidneys actively secrete excess hydrogen ions into the urine, which effectively reduces their concentration in the blood. At the same time, bicarbonate, a base that can help neutralize acids, is reabsorbed back into the bloodstream. This process not only helps to raise the pH back towards the normal range but also ensures that there is enough bicarbonate present to buffer any remaining hydrogen ions.

Thus, this dual action of excreting hydrogen ions and reabsorbing bicarbonate is crucial for the kidneys to help regulate and restore the acid-base equilibrium in the body. This function underscores the importance of the kidneys beyond just waste filtration; they are integral to maintaining homeostasis concerning pH levels.