3.0 Introduction of acid-based regulation

Acids are by definition substances that can release one or more protons (H⁺ ions) whereas bases are substances that bind protons. The stronger the acid, the more H⁺ released and the lower the pH. The pH is the concentration of unbound H⁺ ions. The stronger the base, the more H+ it can bind and the higher the pH. At low pH, there is an  excess of H⁺, and at high pH there is an excess of hydroxide ions (OH^–).

Acids (H⁺) are able to react with other molecules. It is for this reason that low pH, for example, can inhibit or even destroy proteins, such as enzymes.

So it is important that the body’s pH must be carefully controlled

Learning Outcomes

After studying the chapter on acid-base regulation, you should be able to:

• describe what an acid and a base is, and explain what is meant by pH
• describe the pH scale
• explain the physiological pH values
• explain what a buffer is and what are the main substances that act as buffers in the body
• explain how respiration is involved in the regulation of pH
• explain how the kidney is involved in the regulation of pH
• explain the concepts of alkalosis and acidosis