Medical Physiology, 3rd Edition

CHAPTER 28. Acid-Base Physiology

Walter F. Boron

Acid-base physiology is really the study of the proton, or hydrogen ion (H+). Although they are present in exceedingly low concentrations in most intracellular and extracellular fluids, protons nevertheless have a major impact on biochemical reactions and on a variety of physiological processes that are critical for the homeostasis of the entire body and individual cells. Not surprisingly, the body has evolved sophisticated systems to maintain [H+] values within narrow and precise ranges in the blood plasma, intracellular fluid, and other compartments.

This chapter provides the introduction to acid-base physiology, including the chemistry of buffers, the image buffer system, the competition between the image buffer system and other buffers, and the regulation of intracellular pH. In other chapters, we discuss how blood pH—and, by extension, the pH of extracellular fluid—is under the dual control of the respiratory system, which regulates plasma [CO2] (see Chapter 31), and the kidneys, which regulate plasma [image] (see Chapter 39). In addition, we discuss the control of cerebrospinal fluid pH in Chapter 32.

pH and Buffers

Acid-Base Chemistry When Is the Only Buffer

Acid-Base Chemistry in the Presence of and Buffers—The Davenport Diagram

pH Regulation of Intracellular Fluid