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15 Cards in this Set
- Front
- Back
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Why use theories? |
- Summarize and explain observations - Help us understand the aging - Serve as foundations for new ideas to current concepts |
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Stochastic Theories |
Aging is caused by a series of adverse changes in the cell that subsequently lead to replicative errors * Environmental |
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Non-Stochastic Theories |
Aging is caused by replicated errors that are intrinsic and predetermined/preprogrammed |
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Wear & Tear Theory |
* Stochastic - Assumes that continued physical use of the body "wears it out" - Accumulation of cellular by-products expedites the wear & tear process |
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Problems with Wear & Tear Theory |
- The body has repair mechanisms to prevent system failure - Increased use is actually beneficial; bone and muscle deteriorate without use |
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Error Theory |
- Also known: Somatic Mutation Theory - Cell death is causes by negative effects of the internal/external environment - Damage to the genetic structure within cells -> faulty cellular reproduction -> cell death |
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Problems with Error Theory |
Research has not provided adequate support for the theory |
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Cross-linking Theory |
* Stochastic theory - Involves collagen and elastin *Loosely associated -> highly flexible - Chemical reactions create bonds between molecules normally separate - As age increases, collagen and elastin become more closely associated |
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Problem with Cross-Linking Theory |
Theory doesn't provide any sore of preventative mechanism |
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Free Radical Theory |
*Stochastic theory - Cell damage occurs because of oxidation - Cell use oxygen to metabolize energy -> produces a byproduct called a "free radical" - Aggressively attack/destroy cells protective enzymes and anti-oxidants can neutralize free radicals |
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Programmed Aging Theory |
*Non-stochastic - Hayflick & Moorhead suggest a biological clock * Hayflick Limit -> Cells can only divide/multiple a certain number of time before senescence (cell death - Aging is preprogrammed at the cellular level |
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Determined maximum life span for various species |
- Mouse cells -> 15 cellular doublings -> 3 years - Galapagos Tortoise -> 130 doublings -> 100+ years - Human embryo- 50-60 doublings -> 120 years - Human cells- 14-29 doublings -> 120 years |
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Telomeres |
- Stabilize and protect the chromosome during cell division - Shorter the length, higher the risk of cellular death, genetic mutations |
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Immunological Theory |
*Non-stochastic - Decreased immune response & increased autoimmune response - Immune system becomes less effective at warding off invading microbes - Our body becomes less effective at distinguishing own cells from invading cells |
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Stress Theory |
- Response controlled by the endocrine system * Glucocorticoids (cortisol)- increase in energy levels |
