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PHYSIOLOGY OF AGING

PHYSIOLOGY OF AGING. Dr. Ed Soltis Department of Neurosciences Spring 2005. Physiology of Aging. “We are all amateurs; we don’t live long enough to become anything else.” Charlie Chaplin. Significance of Human Aging. People live longer now than ever before

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PHYSIOLOGY OF AGING

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  1. PHYSIOLOGY OF AGING Dr. Ed Soltis Department of Neurosciences Spring 2005

  2. Physiology of Aging “We are all amateurs; we don’t live long enough to become anything else.” Charlie Chaplin

  3. Significance of Human Aging • People live longer now than ever before • By 2030, 20% of the US population will be 65 and older • Significant challenge to medicine - ethical, financial, etc.

  4. Significance of Human Aging • What is “normal” in the aging process - primary aging • More susceptibility to disease - secondary aging • More heterogeneity in the elderly population • Onset indeterminable and progression varied • Genetic and environmental factors

  5. Significance of Human Aging • Gender is a significant factor • Lifestyle a primary factor • Various theories of aging attempt to explain the process - bottom line, there is disruption of homeostasis

  6. Stages of Life • Chronological age typically used to note life’s transitions

  7. Stages of Life • Adulthood is attainment of physiologically optimal integrated function • Function in adulthood is the standard measure • Unsound and incorrect to state that changes with aging are necessarily “abnormal” • Three observations of the elderly: • Greater heterogeneity in responses • Changes in function do not occur simultaneously • Changes in function do not occur to the same degree • Old age should not be viewed as a “disease” nor should a time clock be put on aging

  8. Human Longevity • Significant increase in longevity over past centuries • Due to decline in deaths resulting from infectious disease along with improved public health • Heart disease, cancer and stroke now most common cause of death • Death rates have actually declined in the elderly • Is there a limit to human life span and should we prolong life at the expense of overall health? • We should be talking in the context of “health span” not life span

  9. Successful Aging • Chronologic age and physiologic age not the same • Due to complex interactions of genetics and environment • Individuals “age” at different rates and there is significant variability

  10. Successful Aging • Prevalence of disease increases with age • Proposed pathways of aging: • Aging with disease and disability • Usual aging; absence of pathology but presence of decline in function • Healthy aging; no pathology or functional loss • Pathway goals: • De-emphasize aging characterized by decline • Emphasize heterogeneity among elderly • Underscore positive pathway of aging • Highlights possible avoidance of disease associated with aging

  11. Successful Aging - homeostasis less efficient, but still present

  12. Successful Aging • Heterogeneity of various values and functions • Many associated with physical inactivity

  13. Successful Aging • Recent research: • Elderly individuals with weak muscles are at greater risk for mortality than age-matched individuals • Increase in amount and rate of loss of muscle increases risk of premature death • Physical inactivity is 3rd leading cause of death in US and plays role in chronic illnesses of aging

  14. Aging and Disease • Aging is associated with increase in incidence and severity of disease • Factors predispose individuals to functional losses later in life

  15. Cell Senescence and Death • Cell senescence much like apoptosis • Occurs throughout life • Arresting growth of damaged/dysfunctional cells • Beneficial early in life; may contribute to aging later

  16. Cell Senescence and Death • Inducers can cause cancer • Senescence allows cells to respond to inducers, but cells withdraw from growth cycle - incapable of tumorigenesis • Contribution of cell senescence to aging: • Altered secretions of cells • Proteases, inflammatory cytokines, growth factors • Erosion of structure and integrity of tissues

  17. Current Areas of Research • Caloric Restriction • Altered dietary intake • Insulin-like growth factor (IGF) • Pharmaceuticals • Most, if not all, of these have a similar goal of targeting reactive oxygen species, underscoring what appears to be a substantial role of oxidants in the aging process

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