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Intrinsic ageing and extrinsic ageing are terms used to describe cutaneous ageing of the skin and other parts of the integumentary system, which while having epidermal concomitants, seems to primarily involve the dermis. [1] Intrinsic ageing is influenced by internal physiological factors alone, and extrinsic ageing by many external factors.
Intrinsic mortality is defined as mortality due to ageing, the physiological decline due to innate processes, whereas extrinsic mortality is the result of environmental factors such as for example predation, starvation, accidents and others. Flying animals such as bats, for example, have fewer predators, and therefore have a low extrinsic ...
Extrinsic mortality is implicit in both classical theories of aging and non-classical studies of aging. In both cases, its existence causes a selective pressure for either longer lifespans and later reproductive periods or shorter lifespans and earlier reproductive periods.
These are examples of how the free-radical theory of aging has been used to neatly "explain" the origin of many chronic diseases. [24] Free radicals that are thought to be involved in the process of aging include superoxide and nitric oxide. [25]
External signs of aging are here understood as those signs of biological aging that qualify as bodily changes in structure occurring outside viscera and visible to the unaided eye See also: Intrinsic and extrinsic aging
How to slow aging. The “Essential 8,” based on guidance from the heart association: Eat better. Consume a diet with a variety of fruits and vegetables, whole grains, healthy protein sources ...
Senescence (/ s ɪ ˈ n ɛ s ə n s /) or biological aging is the gradual deterioration of functional characteristics in living organisms. Whole organism senescence involves an increase in death rates or a decrease in fecundity with increasing age, at least in the later part of an organism's life cycle.
In populations where extrinsic mortality is low, the drop in reproductive probability after maturity is less severe than in other cases. The mutation accumulation theory therefore predicts that such populations would evolve delayed senescence. [5] One such example of this scenario can be seen when comparing birds to organisms of equivalent size.