WHAT MAKES US AGE? Life Cycle II

JOHN TURNER AGE 67 AGE 77

AGE 90 AGE 80 ELEANOR HYNDMAN

WHY DO WE AGE? IS IT GENETICS? ENVIRONMENTAL DAMAGE?

THE BIG QUESTION DEVELOPMENTAL— GENETIC THEORIES Genetic makeup determines factors directly affecting aging Programmed & directed in the body Aging is Predetermined ENVIRONMENTAL— NON- GENETIC THEORIES Due to random events that occur over time Aging caused by environmental damage Controlled extrinsically

Theories of Aging Finite Lifespan Immune System Failure Hormonal Energy/Caloric Restriction Error Theory Redundant DNA Transcription Cross-Linking

Finite Limit Theory Hayflick & Moorehead (1961) Landmark Study--Cells Have Time-clock Cells Have Limited Life Span –Apoptosis=Programmed cell death Cells Proliferated and Divided Alterations & Degeneration Cessation of Growth & Division

Neuroendocrine & Hormonal Theory Denckla (1974) Endocrinologist Gerontologist Aging Mediated in Brain Functional Decrements in neurons and associated hormones dictates aging rates

Immunological Theory Walford (1969, 1979) Reduced T-cell function with age –Decline in Immune System Function Immune System unable to distinguish between self & non-self –Age associated increase in autoimmune disorders –Lupus, Scleroderma

Free Radical Theory Accumulates Over Time from Oxygen Metabolism –Charged Ion with unpaired electron –Damages membrane proteins, mitochondria, etc. –Decreased cellular integrity Free radicals associated with atherosclerosis, cancer

Metabolism, Free Radicals, & Life Span Metabolic Rate Directly Related to Free Radical Production Inverse Relationship Between Metabolic Rate & Life Span Hypothesis--Lower metabolic rate, lower free radical production, increase life span

Caloric Restriction Theory Walford (1987)--”Dr In Vivo” Restriction of Caloric Intake High quality nutrient/low calorie diet increases longevity –Supplements with vitamins/minerals/moderate exercise Gradually lose weight until maximal metabolic efficiency, retards aging

Error Theory Orgel (1963) “Any accident or error in either the machinery or the process of making proteins would cascade into multiple effects” DNA--RNA--protein synthesis Accumulation of errors over time “Error Crisis” result in impaired cell function

Redundant DNA Medvedev (1972) Combination of Finite Limit & Error Ability to repair errors to genetic material decreases with age Errors in Cellular DNA Reserve DNA (error free) utilized Cell death when reserve DNA gone

Cross-Linking Theory Bjorksten (1942) Proposed Chemical reaction of Cross Linking of Macromolecules related to aging –Occurred during sun tanning--lose elasticity –Loss of Tissue Elasticity

“Number of hypotheses is generally inversely proportional to the clarity of the problem.” --Frolkis WHY SO MANY THEORIES?

Biologic Gerontology New Field Can One Single Theory Explain All Aging Processes? IS THERE A RIGHT ANSWER?