Metabolism (introduction)

METABOLISM

Metabolism is the continuous vital process of breaking down organic matter and forming new substances within the body's tissues. The word is derived from the Greek word metabole, meaning “change”. Indeed, the body is in a constant state of change.

The breaking-down process is called catabolism, whereas the forming process is called anabolism. Metabolic reactions are affected by several reaction-accelerating body enzymes (biocatalysts). In addition, metabolism is regulated by hormones, various growth factors, vitamins, and minerals as well as the autonomic nervous system. Vitamins will be discussed in more detail in part 3 and hormones in part 4. Examples of metabolism include the breaking down of carbohydrates, proteins, and fats into energy (the citric acid cycle), the removal of superfluous ammonia through urine (the urea cycle) and the breaking down and transfer of various chemicals.