Bio Aging Ch 1 notes.txt

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Bio Aging Ch 1 notes.txt
2012-10-20 19:42:38

bio aging ch 1
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  1. Metaphysics
    • Part of philosophy concerned with 'how do we age?'
    • Seen as positive or negative event
    • Positive: Robert Browning, fulfillment of life' journey
    • Negative: Dylan Thomas, it's the END of all achievements
  2. Gerontology
    • Branch of science asking the question 'what is aging?'
    • Observational: Shakespeare's 7 ages of development & Aristotle's LOSS of heat with age theory
    • Experimental: Metchnikoff and Raymond Pearl 1st to carryout aging experiments & Alex Comfort compiled data of aging of different organisms
  3. Ethics
    • part of Philosophy concerned with 'should we interfere with aging process?'
    • Hayflick: opposes attempts to INCREASE max lifespan
    • Walford: in FAVOR of increasing max life
    • Robert Arking (txtbook author): favors attempts to heal sick and increase lifespan but does not believe or desire human immortality
    • Thomas: agrees with Walford in desire for immortality, although social upheal would result
  4. Bernard Strehler criteria for age-related changes leading to senescence
    • 1. cumulative- increase over time
    • 2. progressive - change in one direction, NOT in reverse
    • 3. intrinsic - generated internally, not stopped by envir
    • 4. deleterious - REDUCE fxn, lead to INCREASE in mortality rates over time
  5. Most widely used method to measure if aging is occurring in a population
    Age-specific mortality rate
  6. Type I, II and III survivorship patterns on semi-log survivorship plot
    • Type I (senescence): convex slope going downwards, showing INCREASE mortality with age
    • Type II(nonsenescence): linear slope going down, constant mortality and life expectancy
    • Type III(antisenescence): concave slope going down, showing DECREASED mortality and increased life expectancy with age
  7. Halley
    made 1st human life table
  8. Weismann
    • proposed DISPOSABLE SOMA theory of aging
    • Theorized that somatic tissues always aging
    • Germ cells, however, do NOT age
  9. Charles Child
    • dissection with flatworms showed if cutting off head, able to regenerate infinite # of times
    • if cut the tail, worm eventually dies
  10. Leonard Hayflick
    human diploid fibroblasts have LIMIT to amount of cell divisions can occur in tissue culture (aka Hayflick limit)
  11. Why population data, although can suggest whether of not Type I aging is occurring, shows potential problems to predict patterns
    • 1. pop. avgs can lose some info about INDIVIDUALS
    • 2. Death rates altered by ENVIRON. changes
    • 3. Death thresholds may Differ among indiv.
    • 4. Accidental deaths may mask changes in age-related deaths
  12. To reduce problems with population data
    • Longitudinal data: info on same indiv. @ multiple timepoints, vs. cross-sectional data (all members of pop @ one timepoint)
    • Baltimore Longitudinal Study & Framingham Study: largest longitudinal studies in world
  13. Biomarkers of aging
    Consistent changes in phyisiological parameters with age in diff. indiv.
  14. Bottoms up approach to study aging
    free radical theory by Denham Harman: major success of this approach, by examining free radical
  15. Top-down approach to study aging
    iron-accumulation hypothesis supports this approach, although can only divide pop so much before accidental deaths & other factors occur
  16. Problems to gerontology
    • Longitudinal studies must take mortality rates into account, and hard for rodents who have longer lifespans, vs fruitflies for example
    • protozoa do not have this problem
  17. Intraspecific plasticity
    • Longevity can be influenced by ENVIRONMENTAL changes
    • organisms with high reliability predictions with specific environments:
    • 1. salmon - all die w/in same month after spawning upriver, from parasite infections
    • 2. perennial plants - all die within same week in response to light & temp stimuli
  18. Interspecific plasticity
    • a. Caleb Finch: wide range of aging patterns observed in nature classified into 3 groups:
    • 1. Rapid
    • 2. Gradual
    • 3. Negligible senescence
    • Problem is that it some species can be classified in more than 1 throughout their life (ie: bamboo, perennial plants)
    • b. Raymond Pearl: classified based on Type I, II and III.
    • Has advantage of NO ambiguity