briefly explain causes of ageing
Answers
Answer:
Explanation:The causes of aging are uncertain; current theories are assigned to the damage concept, whereby the accumulation of damage (such as DNA oxidation) may cause biological systems to fail, or to the programmed aging concept, whereby internal processes (such as DNA methylation) may cause aging.
Answer:
Explanation:Ageing or aging (see spelling differences) is the process of becoming older. The term refers especially to human beings, many animals, and fungi, whereas for example bacteria, perennial plants and some simple animals are potentially biologically immortal. In the broader sense, aging can refer to single cells within an organism which have ceased dividing (cellular senescence) or to the population of a species (population ageing).
In humans, aging represents the accumulation of changes in a human being over time[1] and can encompass physical, psychological, and social changes. Reaction time, for example, may slow with age, while knowledge of world events and wisdom may expand. Aging is among the greatest known risk factors for most human diseases: of the roughly 150,000 people who die each day across the globe, about two-thirds die from age-related causes.
The causes of aging are uncertain; current theories are assigned to the damage concept, whereby the accumulation of damage (such as DNA oxidation) may cause biological systems to fail, or to the programmed aging concept, whereby internal processes (such as DNA methylation) may cause aging. Programmed aging should not be confused with programmed cell death (apoptosis).
Contents
1 Definitions
2 Aging versus immortality
3 Effects
4 Biological basis
4.1 Programmed factors
4.2 Damage-related factors
5 Prevention and delay
5.1 Lifestyle
5.2 Medical intervention
5.3 Research projects and prizes
6 Society and culture
6.1 Economics
6.2 Sociology
6.3 Health care demand
6.4 Self-perception of aging
6.5 Successful aging
6.6 Cultural references
7 See also
8 References
9 External links
Definitions
Mortality can be used to define biological aging, which refers to an organism's increased rate of death as it progresses throughout its lifecycle and increases its chronological age.[2] Another possible way to define aging is through functional definitions, of which there are two main types[2] The first describes how varying types of deteriorative changes that accumulate in the life of a post-maturation organism can leave it vulnerable, leading to a decreased ability of the organism to survive. The second is a senescence-based definition; this describes age-related changes in an organism that increase its mortality rate over time by negatively affecting its vitality and functional performance.[2] An important distinction to make is that biological aging is not the same thing as the accumulation of diseases related to old age; disease is a blanket term used to describe a process within an organism that causes a decrease in its functional ability.[2]
Aging versus immortality
Immortal Hydra, a relative of the jellyfish
Human beings and members of other species, especially animals, age and die. Fungi, too, can age.[3] In contrast, many species can be considered immortal: for example, bacteria fission to produce daughter cells, strawberry plants grow runners to produce clones of themselves, and animals in the genus Hydra have a regenerative ability by which they avoid dying of old age.
Early life forms on Earth, starting at least 3.7 billion years ago,[4] were single-celled organisms. Such organisms (Prokaryotes, Protozoans, algae) multiply by fission into daughter cells; thus do not age and are innately immortal.[5][6]
Aging and mortality of the individual organism became possible with the evolution of sexual reproduction,[7] which occurred with the emergence of the fungal/animal kingdoms approximately a billion years ago, and the evolution of seed-producing plants 320 million years ago. The sexual organism could henceforth pass on some of its genetic material to produce new individuals and could itself become disposable with respect to the survival of its species.[7] This classic biological idea has however been perturbed recently by the discovery that the bacterium E. coli may split into distinguishable daughter cells, which opens the theoretical possibility of "age classes" among bacteria.[8]
Even within humans and other mortal species, there are cells with the potential for immortality: cancer cells which have lost the ability to die when maintained in a cell culture such as the HeLa cell line,[9] and specific stem cells such as germ cells (producing ova and spermatozoa).[10] In artificial cloning, adult cells can be rejuvenated to embryonic status and then used to grow a new tissue or animal without aging.[11] Normal human cells however die after about 50 cell divisions in laboratory culture (the Hayflick Limit, discovered by Leonard Hayflick in 1961).[9]