theory of aging
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presentation about aging theory by doctor ahmad zahranTRANSCRIPT
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