Cellular aging is a natural process that occurs over time as a result of both intrinsic genetic factors and environmental exposures. While the average lifespan has increased significantly from 20-25 years historically to nearly 80 years now, the maximum human lifespan remains around 110 years. As people age, they experience deterioration in multiple organ systems such as the cardiovascular, nervous, musculoskeletal, visual, auditory, immune, and integumentary systems which makes them more vulnerable to disease. Cancers also become more common starting at age 50.

1. CELLULAR AGING
Old age is a concept of longevity in human beings. The consequences of aging appear after reproductive age.
However, aging is distinct from mortality and disease although aged individuals are more vulnerable to
disease.
The average age of death of primitive man was barely 20-25 years compared to life-expectancy now which is
approaching 80 years, survival being longer in women than men
However, the maximum human lifespan has remained stable at about 110 years. Generally, the life expectancy
of an individual depends upon the following factors:
1. Intrinsic genetic process i.e. the genes controlling response to endogenous and exogenous factors initiating
apoptosis in old age.
2. Environmental factors e.g. consumption and inhalation of harmful substances, diet, role of antioxidants etc.
3. Lifestyle of the individual such as diseases due to alcoholism (e.g. cirrhosis, hepatocellular carcinoma),
smoking (e.g. bronchogenic carcinoma and other respiratory diseases), drug addiction.
4. Age-related diseases e.g. atherosclerosis and ischaemic heart disease, diabetes mellitus, hypertension,
osteoporosis, Alzheimer’s disease, Parkinson’s disease etc.
ORGAN CHANGES IN AGING
Although all organs start showing deterioration with aging, following organs show
evident morphologic and functional changes:
1. Cardiovascular system: Atherosclerosis, arteriosclerosis with calcification, loss
of elastic tissue from aorta and major arterial trunks causing their dilatation.
2. Nervous system: Atrophy of gyri and sulci, Alzheimer’s disease, Parkinson’s
disease.
3. Musculoskeletal system: Degenerative bone diseases, frequent fractures due to
loss of bone density, age related muscular degeneration.
4. Eyes: Deterioration of vision due to cataract and vascular changes in retina.
5. Hearing: Disability in hearing due to senility is related to otosclerosis.
6. Immune system: Reduced IgG response to antigens, frequent and severe infections.
7. Skin: Laxity of skin due to loss of elastic tissue.
8. Cancers:80% of cancers occur in the age range of 50 and 80 years.