What Is the Difference Between Respiratory and Metabolic Acidosis and Alkalosis?

According to the Merck Manual, alkalosis and acidosis are medical terms that describe the acid and base balance, or pH, of the blood. Acidosis is present when the level of acidic compounds in the blood is too high. When the level of bases in the blood rises, alkalosis occurs. Acidosis and alkalosis are classified as either respiratory or metabolic depending on the physiologic process that creates the abnormality.

The Merck Manual explains that the body has several mechanisms to ensure proper acid-base balance. One of these is the regulation of carbon dioxide, which is a mildly acidic waste product of oxygen use when we breathe. This acidic waste accumulates in the blood and is exhaled through the lungs. As blood becomes more acidic, the brain sends a signal to the lungs that causes breathing to speed up and become deeper. Thus, the lungs release more carbon dioxide, which causes a decrease in acidity and an increase in blood pH. When the lungs do not remove carbon dioxide efficiently, respiratory acidosis occurs. Similarly, if breathing speeds up and deepens suddenly, it causes a drop in carbon dioxide levels, resulting in respiratory alkalosis and increased blood pH.

According to Bright Hub Education, the kidneys also regulate acid-base balance by retaining or releasing acidic and basic compounds in response to shifts in blood pH. Additionally, the kidneys are responsible for the release of bicarbonate. The body's primary buffer, bicarbonate binds to hydrogen in the body to create carbon dioxide and water, which are then eliminated by the kidneys and the lungs. Acidosis or alkalosis that is caused mainly by a malfunction in the kidneys is referred to as metabolic.