Introduction to Human Aging

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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

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Introduction to Human Aging
B. Number and percentage of the elderly

• In the US, more persons gt 65 than lt 25 years of
  age

2. Median age was 32 in 1995 was 36 in 2000,
and will be 42 by 2040
year pop. number gt 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
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Introduction to Human Aging
C. Percentages of the elderly
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Introduction to Human Aging
D. Problems for younger members of society

• 30 of health care resources used by persons gt65
  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.
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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.

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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
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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.

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Introduction to Human Aging
H. What is a feedback system?
1. Negative feedback
2. Positive feedback
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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

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Introduction to Human Aging
J. General aging changes in the body

• Body structural changes

a. gradual decline in height beginning in the
late 30s

• 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
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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-50s, then
lose
ii. women gain weight into the 60s, then lose
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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
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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
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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 gt70 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

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