AgingAgingByBy

Ahmed ZahranAhmed ZahranMD, Internal MedicineMD, Internal Medicine

“We are all amateurs; we don’t live long enough to become anything else.”

Charlie Chaplin

Stages of lifeStages of life

Aging is a syndrome of changes that are deleterious, progressive, universal and thus far irreversible

Some gerontologists prefer to use the word senescence

Who is old?

• Limit is usually 65 years (retirement)

• Young old(65-74)

• Middle old(75-84)

• The oldest old (85 and above)

Theory of Aging

Programmed aging

Aging due to something inside an organism's control mechanisms that forces elderliness & deterioration

Structural damage

Is not the result of any specific controlling program, but is the effect of the sum effect of many kinds of environmental assaults

Structural Damage Theories

• Structural damage theories of aging are based on the view that the molecular components of cells, over time, begin to malfunction and break down:

Wear and Tear Theory:• the theory postulates that the daily grind of life,

in particular abuse or overuse, degeneration of cartilage and eventual grinding of bone on bone is an example of the aging process on body joints, as wear and tear exceed the body’s ability to repair.

Waste Accumulation Theory:• As we age, our cells accumulate waste products

as a consequence of normal metabolic processes in the cells. It is believed that this build-up of toxic “sludge” eventually compromises normal cell functions.

Faulty Reconstruction Theory:

As we age, the repair process begins to produce faulty reconstruction materials that compromise the repair job and weaken the cell

Molecular Cross-linkage Theory:

Disruption of cross linking between protein molecules (collagen found in skin , ligaments) and glycation of lipids and proteins lead to disrup function of these molecules with acceleration of aging

Mitochondrial Damage Theory:

• Theory postulates that the oxidative processes occurring deep within the mitochondrial membranes eventually damage the organelle, leading to a loss of function. Once mitochondria are lost to the cell, they cannot be replaced, leading to a gradual loss of energy and function in cells over time.

Free Radical Theory of Aging

Free radicals are atoms, molecules and molecular fragments

They are powerful oxidizing agents, created by the cell’s own metabolic reactions and also present in the environmentnt

The free radicals most critical to the aging process include:

superoxide ion, hydrogen radical, hydrogen peroxide and hypochlorous acid.

In general, free radicals are extremely unstable, short-lived and very reactive chemically, inflicting substantial damage and changing the chemical nature of structural molecules within the cell.

Programmed agingProgrammed senescenceAging results from gene interference with

the ability to the cell to reproduceHormonalBiological clock alters hormone

secretion resulting in tissue changesImmunological T-Cell function decline increasing the

chance of developing infection and cancer

Telomere shortening

Shortening of telomeres in somatic cells lessens the ability of cells to divide

Telomeres consist of the six-base repeating sequence TTAGGG at the end of each chromosome

Manifestation of aging

Gray hairMenopauseGradual reduction in height and weightlossLower metabolic rate, Lower reaction times, Declines in certain memory functions, Declinesin sexual activityandFunctional decline in audition, olfaction, and vision, Declines in kidney, pulmonary, and immune functions, Declines in exercise performance, and multiple endocrine

changes.

Effect of aging on organ and systems

Cardiovascular

Slow heart rate

Increase blood pressure

Diastolic dysfunction

Postural hypotension

Atherosclerosis

Arrhythmias

Respiratory

Chest wall stiffness

Decline of maximum breathing capacity

GIT

Shrinkage of the root pulp

Decline of taste and smell

Decrease lower esophageal sphincter tone

Decrease liver weight

Tendency to constipation

Renal

Decreased GFR

Bladder wall changes

UTI

Urinary incontinence

Prostate problems

Liability to dehydration and volume depletion

Liability to electrolyte disturbances

Endocrine

Decrease G H levels

Thyroid abnormalities

Hypoclcemia and hyperparathyroidism

Impaired insulin response to glucose

Decreased testosteron

Menopause

Immune system

Decrease size of thymus gland

Decreased cellular and humoral immunity

Increased susceptability to infections

Hematological

Less response to increased demands

Less response to erythropoetin

Muscloskeletal

Decrease bone mass and density

Tendons and ligaments become more lax

Cartilage become more calcified

Liability to osteoporosis and fractures

Neurological

Brain shrinkage

Decreased ability to distinguish colors

Hearing loss

Change of sleep patterns

Decreased cognitive function

Memory disturbances

Delerium and dementia

Prevention of aging

Caloric restriction and periodic fasting

Vegetables and fruits

Avoid smoking

Exercise programms

Social life

Antioxidants

Early diagnosis of diseases