Meaning of Metabolism

What is Metabolism:

It is known as metabolism to the set of chemical transformations that take place constantly in the cells of living organisms.

The term “metabolism” was coined by the Prussian physiologist Theodor Schwann in the mid-19th century from a Greek root and suffix: metabolism (change) and ism (quality). In this way, Schwann conceptualized the quality of living beings to change or transform some substances through complex internal chemical processes.

how metabolism works

Metabolism is the process by which carbohydrates, proteins, fats, and other substances are transformed in the body. This transformation produces heat, carbon dioxide, water and debris, in order to produce energy to carry out essential chemical transformations for the organism and to develop muscular activity.

Metabolic activity includes the absorption, transformation, and elimination of substances that allow cells to fulfill their energetic or synthetic functions. This activity is composed of two phases.


It is a stage of the metabolic process in which the ingested substances are transformed into new organic matter.

For example: protein synthesis in muscle tissue from amino acids.


It is a phase of the metabolic process in which energy is produced and destructive chemical reactions are discarded.

For example: the breakdown of the glucose molecule that is transformed into energy and water.

The metabolic process is carried out thanks to the enzymes synthesized in the cells. While the thyroid glands and the liver act as regulators of the process. For this reason, a malfunction of the thyroid can generate conditions such as hypo or hyper thyroidism, which usually lead to metabolic problems (weight gain or loss).

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While glucose or sucrose is produced from carbohydrates in the liver, a fundamental substance for some organs that can only obtain energy from glucose, as well as being the organ in which some proteins are synthesized.

See also:

  • Anabolism.
  • Catabolism.

types of metabolism

The metabolic process can be of two types:

aerobic metabolism

Aerobic metabolism involves obtaining energy out from the combustion of carbohydrates in the presence of oxygen. This type of metabolic process is also known as pulmonary respiration or oxidative metabolism.

anaerobic metabolism

Anaerobic metabolism is carried out from the combustion of carbohydrates in the absence of oxygen in order to obtain energy. Glucose and glycogen from carbohydrates do not break down completely, as they require oxygen to do so, so they turn into lactic acid in humans.

In both processes, both anabolism (synthesis) and catabolism (degradation) take place.

See also Cellular respiration.

basal metabolism

Basal metabolism is the minimum amount of energy a cell requires to survive. and carry out essential functions, such as breathing.

This energy expenditure depends on several factors such as age, sex, height, amount of muscular energy, among others, and is calculated in kilocalories/day.

The Food and Agriculture Organization of the United Nations proposes to calculate the basal metabolic rate (BMR) as follows:

For ages between 10 and 18:

  • Women: 7.4 x weight in kilograms + 428 x height in meters + 572
  • Men: 16.6 x weight in kilograms + 77 x height in meters + 572

Basal metabolic rate can also be calculated through the Harris Benedict equations:

  • Male: 66.4730 + ((13.751 x mass (kg)) + (5.0033 x height (cm)) – ((6.75 x age (years))
  • Female: 655.1 + ((9.463 x mass (kg)) + (1.8 x height (cm)) – ((4.6756 x age (years))
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The result of these equations will indicate what the daily energy expenditure is.

See also Kilocalories.