Biogerontology

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The biogerontology (gr. Bios "life," Geron "old man," logos "doctrine"), the branch is developmental biology , which is biological with the research into the causes aging ( Engl. Aging , AE aging ) and their consequences, the senescence ( lat. senescere = ' getting old') employed by single cells ( biochemistry ) and organisms ( physiology ).

Senescence comprises the generally irreversible processes that inevitably lead to the death of an organism, its organs or individual cells. Aging is one of the main causes of the death of an organism. In addition, phenomena of senescence play a role in normal catabolic metabolism ( cell breakdown ). More than 300 different theories of aging are discussed.

Biogerontology is an important basic discipline of gerontology , which is specifically geared towards human medicine . In contrast, geriatrics deals with the biological consequences of aging, i.e. the various diseases associated with age (the terms infirmity and old age are rarely used in technical jargon). The corresponding specialist field of veterinary medicine is veterinary gerontology , that of botany is general plant physiology .

Aging of fibroblasts

Causes of aging

Primary causes

From a biology perspective, primary aging, also called physiological aging, is caused by cellular aging processes that also take place in healthy organisms. Primary aging defines its maximum achievable life span for an organism, around 115 to 120 years for humans. There are different answers to the question of why organisms age. To date, none of these aging theories has been accepted as a scientifically comprehensive answer. The theories can be assigned to three biological approaches:

  • Wear theories, wear theories, even passive aging called
    • Energy consumption- related theories of aging such as the CR hypothesis ( calorie reduction ). In simple terms: the more a living being - measured by its body weight - eats, the shorter it lives.
  • Evolution related theories
  • Cell biological approaches that suspect genetic influences

Secondary causes

Helicases , which open the DNA double helix, are a prerequisite for reading ( transcription ) or doubling the stored information ( replication ), as well as for repairing DNA damage . For example, people suffering from Werner syndrome as a result of a defect in the protein WRN, a helicase , are subject to a rapid aging process.

Effects of Aging

There are many causes for aging, one of the main ones is probably attributed to the free radicals :
The mitochondria present in most cells use the inhaled oxygen to produce energy in the form of ATP . With 1 to 2% of the oxygen, however, this process (see end oxidation ) is incorrect. The oxygen atoms leave the process with an unpaired electron on the last shell and are therefore extremely reactive. These oxygen atoms form the main group of free radicals , the reactive oxygen species (ROS). If these particles hit another membrane, other proteins or chromosomes, they can be damaged or even destroyed. Antioxidant systems (vitamins A, C, E, uric acid, various enzymes) are responsible for capturing free radicals. Nevertheless, it is currently estimated that around 10,000 DNA damage per day per cell in humans can be repaired for the most part. This makes it clear that the effectiveness of the body's own repair mechanisms essentially determine the lifespan of the individual, the quality of which in turn is genetically determined. Free radicals are associated with various chronic diseases ( adult diabetes , Parkinson's disease , Alzheimer's dementia ).

Senescence in plants

In botany , phenomena of senescence (dropping of leaves from trees , death of above-ground parts of plants from perennials and the like) are part of the normal growth process. In plants, senescence can be controlled by phytohormones . Cytokinins prevent aging processes, ethylene promotes these (e.g. leaf senescence, abscission of leaves). Chronobiological relationships in particular come into consideration here.

See also

literature

Historical literature
  • W. Brandt: Chemical processes in the body during aging. Chemiker-Zeitung 67 (21), pp. 269-273 (1943), ISSN  0009-2894
Current literature
  • Hans-Jörg Ehni: Ethics of Biogerontology . Springer Fachmedien Wiesbaden 2014, 288 pp. ISBN 978-3-658-03377-4
  • Guarente, Partridge, Wallace: Molecular biology of aging . Cold Spring Harbor 2008, ISBN 978-0-87969-824-9
  • Tomas Prolla et al .: Science , Vol. 309, p. 481, 2005 (on: Mutations in mitochondrial DNA as key factors for aging)
  • Günter Ahlert: Aging - the result of ecological adaptation . Karger, Basel 1996, 67 pages, ISBN 3-8055-6361-2
  • Robert Zwilling: The Enigma of Aging. Biology in our time 37 (3), pp. 156-163 (2007), ISSN  0045-205X
  • Karin Krupinska: Aging and Age in Plants. Biology in our time 37 (3), pp. 174-182 (2007), ISSN  0045-205X
  • Ludger Rensing: Which cellular factors determine aging? The limits of service life. Biology in our time 37 (3), pp. 190-199 (2007), ISSN  0045-205X

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