Introduction to nutrition

Abstract

Nutrition is a collective term for the processes by which an organism obtains chemical compounds for the release of energy, for growth and repair, the production of secretions and the maintenance of a steady internal environment. The chemical compounds are nutrients and their sources vary according to the type of nutrition concerned. Autotrophic (self-feeding) organisms include the pigmented plants and chemosynthetic bacteria. They are able to build up complex organic nutrients from simple inorganic substances by methods described in chapter 5. Heterotrophic organisms need a supply of readymade organic nutrients from their environment and include all the animals and fungi, most bacteria and a few flowering plants which lack photosynthetic pigment. Heterotrophic nutrition is discussed in chapter 6.