Catabolism is the set of metabolic pathways that break down large molecules such as polysaccharides, lipids, nucleic acids, and proteins into smaller units like monosaccharides, fatty acids, nucleotides, and amino acids. This breakdown releases energy, some of which is used to synthesize adenosine triphosphate (ATP), the primary energy carrier for cellular processes. Catabolism is the destructive part of metabolism, complementing the constructive anabolic reactions. Examples include glycolysis, the citric acid cycle, and the breakdown of fat in adipose tissue. Cellular wastes like carbon dioxide and urea are produced during oxidation processes that release chemical energy.
Catabolic hormones
There are many signals that control catabolism. Most of the known signals are hormones and the molecules involved in metabolism itself. Endocrinologists have traditionally classified many of the hormones as anabolic or catabolic, depending on which part of metabolism they stimulate. The so-called classic catabolic hormones known since the early 20th century are cortisol, glucagon, and adrenaline (and other catecholamines). In recent decades, many more hormones with at least some catabolic effects have been discovered, including cytokines, orexin (known as hypocretin), and melatonin.
| Hormone | Function2 |
|---|---|
| Cortisol | Released from the adrenal gland in response to stress; its main role is to increase blood glucose levels by gluconeogenesis. |
| Glucagon | Released from alpha cells in the pancreas either when starving or when the body needs to generate additional energy; it stimulates the breakdown of glycogen in the liver to increase blood glucose levels; its effect is the opposite of insulin; glucagon and insulin are a part of a negative-feedback system that stabilizes blood glucose levels. |
| Adrenaline | Released in response to the activation of the sympathetic nervous system; increases heart rate and heart contractility, constricts blood vessels, is a bronchodilator that opens (dilates) the bronchi of the lungs to increase air volume and oxygen supply in the lungs, and stimulates gluconeogenesis. |
Etymology
The word catabolism is from Neo-Latin, which got the roots from Greek: κάτω kato, "downward" and βάλλειν ballein, "to throw".
See also
- Autophagy
- Dehydration synthesis
- Hydrolysis
- Nocturnal post absorptive catabolism
- Psilacetin § Pharmacology
- Sarcopenia
External links
- Media related to Catabolism at Wikimedia Commons
References
de Bolster, M.W.G. (1997). "Glossary of Terms Used in Bioinorganic Chemistry: Catabolism". International Union of Pure and Applied Chemistry. Archived from the original on 2017-01-21. Retrieved 2007-10-30. https://web.archive.org/web/20170121172848/http://www.chem.qmul.ac.uk/iupac/bioinorg/CD.html#8#8 ↩
This article incorporates text available under the CC BY 4.0 license. Betts, J Gordon; Desaix, Peter; Johnson, Eddie; Johnson, Jody E; Korol, Oksana; Kruse, Dean; Poe, Brandon; Wise, James; Womble, Mark D; Young, Kelly A (June 8, 2023). Anatomy & Physiology. Houston: OpenStax CNX. 24.1 Overview of metabolic reactions. ISBN 978-1-947172-04-3. 978-1-947172-04-3 ↩