Physiology is the study of how living things function. Scientists who study physiology are called physiologists. Their studies range from the most basic unit of organisms, the cell, to complex organs and organ systems, such as the brain and digestive system.
Physiologists study how different parts or organs of an organism work together to achieve a particular function. In people, for example, the digestion of food involves the action of hormones and other chemicals produced by the stomach, liver, and pancreas. Muscle contraction occurs through the action of chemical messengers produced by nerves that supply the muscle.
By learning how the body functions normally, physiologists and doctors are better able to understand what happens when organs function abnormally. They can then prescribe the best treatment. For example, the thyroid gland uses iodine to make thyroxine, a hormone that affects the entire body. If iodine is too low in the diet, the thyroid gland expands, forming a large mass called a goiter. This condition can be corrected by including iodine in the diet. Studies of the circulatory and nervous systems have helped doctors understand and treat heart disease, stroke, and high blood pressure. Cell physiologists, who study the properties of individual cells, hope to learn what causes some cells to become cancerous.
