Final answer:
Proteins and some minerals act as buffers, particularly the bicarbonate system, to prevent changes in the acid-base balance of body fluids by absorbing excess hydrogen and hydroxide ions.
Step-by-step explanation:
The substances that help prevent changes in the acid-base balance of body fluids are proteins and some minerals. These substances act as buffers, which absorb excess hydrogen ions (H+) and hydroxide ions (OH-) to prevent drastic changes in pH. In the human body, buffers maintain the pH of blood and other fluids within a narrow range, thereby ensuring proper physiological functioning.
An important buffer system in the human body is the bicarbonate system, which is the primary buffering system of the interstitial fluid (IF) surrounding the cells in tissues. Additional buffer systems include plasma proteins, phosphate, as well as hemoglobin inside red blood cells. Both the respiratory and renal systems also contribute to maintaining acid-base homeostasis by regulating the removal of carbon dioxide (CO2) and hydrogen ions from the body.