Growing old {aging, development} changes DNA, protein, hormones, cells, tissues, and organs.
causes
Autoimmunity or immune-system breakdown can cause aging. Pituitary hormone and/or thymosin decrease can cause aging. Thymus thymosin keeps immune system active. Structural-molecule changes, as collagen has more cross-links and stiffens, can cause aging.
effects
Aging impairments typically result from disease, trauma, or disuse, not age itself.
effects: biology
Brain deterioration causes most aging effects. Random brain activity increases. Serum globulin becomes higher. Fracture-healing rate decreases.
effects: behavior
Performance ability peaks at 26 and then slowly declines. Slower decision making, especially for tasks in which responses cause signals for next response, slows activities slightly. Older people pay attention to responses more, rather than to next task.
Older people learn facts and skills more slowly but do not forget more rapidly. Verbal ability peaks at 50 and sharply declines after 70.
effects: senses
Signals from sense organs to brain and among brain parts become weaker. Ability to understand speech does not decrease with age, unless people cannot hear frequencies below 1800 Hz, three octaves above middle C. Trauma causes most hearing loss. Aging causes reduced sensitivity to vibration and pain. Smell loses sensitivity.
Aging causes reduced fine-joint-movement sensitivity, reduced clear-focus distance, reduced resting pupil size, increased yellow eye pigment, reduced overall acuity, slight visual-field narrowing, color-discrimination loss, and increased glare susceptibility.
effects: personality
Personality has few trends with age. Adjusting to aging does not relate to health or wealth.
individual differences
Aging rate and effects differ among individuals, and differences become greater with age.
defenses
Aging defenses are apoptosis, suppressor genes, gene redundancy, DNA editing, RNA editing, DNA repair, anti-oxidant free-radical scavenging, defective-protein removal, and damaged-cell removal by immune system.
long life
Physical fitness, genetic factors, low mental pressure, low-fat diet, low-calorie diet, psychological well-being, and living in highlands can contribute to long life. Lowering body temperature and food-intake rate slows aging in animals.
theories
Mammals, even wild animals in zoos, age after adulthood. Perhaps, genetics determines aging, and childhood, sexual maturity, adulthood, and senescence involve separate genetic programs. Perhaps, aging results from diminished energy, slower repair, and increased damage. Perhaps, aging results from free-radical oxidation.
Biological Sciences>Zoology>Development>Aging
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Date Modified: 2022.0224