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* Is the gradual deterioration of structure and function in the body's organ systems. It has five
fundamental features CUPID.
1- First, aging changes are Cumulative, they accumulate gradually over time beginning (20-
30) years of ages.
2- These changes are Universal; they affect all individuals.
3- The changes are progressive; they do not reverse themselves. Exercise delay muscle and
skeletal atrophy; but it does not reverse them in the long run.
4- We presume aging to be Intrinsic to cell and tissues rather than imposed from outside by
disease or chronic environmental sources ex. Tobacco or air pollution.
5- Finally, aging is Deleterious (harmful) and ultimately lead to Death.
* The human life cycle proceed through the stages of infant, child, adolescent, young, adult,
middle aged adult, and elderly adult.
* The aging process is far from uniform among different individual the ages of or in various
parts of the body. An average between the ages of 30-75 a man loses of 64 % of his taste,
44% of the glomeruli in his kidneys, 37% of the axon in his spinal nerve the blood supply to
his brain is 20% less. Some of these declines can be significantly lessened by modifying the
lifestyle (e.g. diet and exercise).
* The aging process is marked by a decrease in homeostatic response to stress.
makes
inheritance and environmental stress
Most aging occurs because a combination of
*
the individual less able to respond to additional stressors .
* Certainly some genetically programmed developmental events do seem to be related to the
aging process .Cells that normally stop dividing when they differentiate appear to be more
subject to the changes of aging than are those that continue to divide throughout life.
Furthermore , cells taken from an older person can divide fewer times than those from a
younger person .
* Cellular aging appears to be related to the fact that most normal human somatic cells are
an enzyme that
,
active telomerase
genetically programmed to lose the ability to produce
replicates the DNA .This loss help protect the individual against the growth of tumors .
* Genetically programmed cell death , apoptosis ; is an essential developmental mechanism
that may play a role in aging .However ,it is thought that most aging is not a direct
mistakes in control of
consequence of the genetic program leading to apoptosis instead ,
may lead to certain degenerative conditions ; such as Alzheimer's disease ,or in
apoptosis
some of the cell deaths that following a heart attack .
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* Aging may be accelerated by certain environmental influences and may vary because of
inherited differences among individuals .
There is evidence that premature aging can be precipitated by :
*
1- hormonal changes
2- by various malfunctions of the immune system ;including autoimmune responses ,
3- by the accumulation of specific waist products within the cell ;
4- by changes in the molecular structure of macromolecules such as collagen ;
5- by damage to DNA by continued exposure to cosmic radiation & X rays .
* Example of aging :
1- Skin becomes wrinkled & losses its elasticity.
2- Hair becomes gray.
3- Bone loses mass & break more readily than the resilient bones of younger people.
4- Muscle mass declines & skeletal muscle fibers atrophy.
5- Lung loses their elasticity & exposed less surface where air oxygenates the blood.
6- The nervous system loses cells ,especially after 60 years.
7- The immune system loses some of its ability to detected foreign substances.
8- Menopause is the major aging event in the reproduction system.