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Introduction to Human Aging. A. Methods used to study aging. longitudinal studies of humans cross-sectional studies of humans lower animal studies. known genetic make-up controlled environment short life spans. Introduction to Human Aging. B. Number and percentage of the elderly.
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Introduction to Human Aging A. Methods used to study aging longitudinal studies of humans cross-sectional studies of humans lower animal studies known genetic make-up controlled environment short life spans
Introduction to Human Aging B. Number and percentage of the elderly • In the US, more persons > 65 than < 25 years of age • 2. Median age was ~32 in 1995; was 36 in 2000, and will be ~42 by 2040 yearpop.number > 65% of elderly 1900 75.6 mil 3.1 mil 4.1 1940 132.3 mil 9.0 mil 6.8 1960 181.0 mil 16.6 mil 9.2 1980 228.0 mil 25.6 mil 11.2 1990 250.0 mil 31.2 mil 12.5 2000 268.5 mil 34.9 mil 13.0 2030 304.7 mil 64.6 mil 21.2
Introduction to Human Aging C. Percentages of the elderly
Introduction to Human Aging D. Problems for younger members of society 30% of health care resources used by persons >65 years (will increase to 50% by 2030) 2. Older persons require more social services and specialized recreational facilities; these require money (increased taxes) 3. The burden of support falls now and will fall more heavily on the younger generations.
Introduction to Human Aging E. General effects of aging • 1. Aging is a continuing, normal process. • 2. Begins at maturity, ends with death • 3. Effects of aging increase at age 40 • Aging is influenced by interactions of genetics • and environmental factors.
Introduction to Human Aging F. Estimated declines in some functions with age (age 30 = 100%) % at age 60% at age 80 nerve conduction velocity 96 88 basal metabolic rate 96 84 cardiac index 82 70 kidney function 96 61 renal plasma flow 89 51 vital capacity 80 58 maximal breathing capacity 80 42
Introduction to Human Aging G. What is homeostasis? 1. based on two Greek roots “homoi” = same “stasis” = standing still • 2. Homeostasis is the sum of all bodily processes, maintaining constancy within limits. • In the absence of homeostasis, dysfunction of the organ systems is more likely, and aging increases the likelihood of death.
high function steady state low time Introduction to Human Aging H. What is a feedback system? • 1. Negative feedback • 2. Positive feedback
Introduction to Human Aging I. Common terms related to aging • Aging • Senescence • Senility • Elderly vs. old vs. very old • Gerontology • Geriatrics • Longevity (mean vs. maximum) • Demography
Introduction to Human Aging J. General aging changes in the body • Body structural changes • a. gradual decline in height beginning in the late 30’s • shortening of lower limbs due to decreasing joint size and feet arches • shortening of trunk due to increase in normal vertebral column curvature and compression of discs • b. gradual deterioration of muscle, causing shoulder width to decrease • c. increased fat deposition in abdomen, hips increase in width
Introduction to Human Aging J. General aging changes in the body • Body structural changes • loss of lung elasticity, leading to increased respiratory effort and increased thoracic circumference • e. changes in body weight • i. men increase weight until mid-50’s, then lose • ii. women gain weight into the 60’s, then lose
Introduction to Human Aging J. General aging changes in the body • 2. Body compositional changes • total body water • young man -- average water = 60% of body weight; drops to 54% with aging • ii. young woman -- average water = 52% of body weight; drops to 46% • b. changes in skin thickness • in general there is a gradual but steady decline in skin thickness • ii. extra adipose tissue accumulates around organs rather than in hypodermis
Introduction to Human Aging J. General aging changes in the body • 3. Body functional changes • Most noticeable changes • movement becomes more difficult • breathing becomes more difficult • elevated blood pressure • changes in dietary habits • changes in urinary frequency and bowel movementsC • b. Functional changes dependent on genetic make-up, lifestyle history, and environment
Introduction to Human Aging K. Importance of regular health exams • 3. Body functional changes • Generally accepted standard intervals • Baseline info for the MD as patient ages • Early detection of problems • Examples • physicals = >70 annualy; 60-70 biannual; 40-60 triannual; 20-40 every 5 years • blood pressure and Pap smear = yearly • cholesterol = every 5 years • proctosigmoidoscopy = every 3 years at 40; yearly at 50 end