Class Notes (807,921)
Canada (492,921)
Gerontology (160)
GRT2111 (18)

Theories of Aging.docx

4 Pages
Unlock Document

University of Ottawa
Vanessa Taler

Theories of Aging What is Aging?  Changes in multiple physiological systems  Increased risk for various diseases: cancer atherosclerosis osteoporosis osteoarthritis skin aging immune senescence How we Think about Aging  “accidental” theories of aging (a.k.a. stochastic theories): aging is caused by a series of adverse events in cells that lead to replicative errors  programmed-aging theories (a.k.a. non-stochastic theories): intrinsic & predetermined /programmed changes in cells  evolutionary theories Stochastic Theories of Aging Wear & Tear Theory  Accumulation of normal injury due to continued use  But humans are not like cars!  Our bodies repair themselves, replace lost cells & damaged proteins, make new mitochondria and molecules, fix DNA, etc.... Somatic Mutation Theory  Mutations occur in cells (soma) due to repeated replication, exposure to toxins, radiation or ultraviolet light.  The body cannot correct/destroy all mutations, but not all of them, and eventually the mutated cells accumulate. Error-Catastrophe Theory  Extension of somatic mutation theory  Aging is caused by cumulative errors in DNA/RNA Free Radical Theory  Cells are damaged by free radicals  Free radicals are chemical byproducts of normal cell metabolism involving oxygen Cross-Linking Theory  Proteins (e.g., collagen, elastin) become cross-linked and thus less flexible Accumulation Theory  a.k.a waste accumulation theory  Aging is caused by the accumulation of substances in cells  e.g., lipofuscin, a brownish pigment left over from the breakdown and absorption of damaged blood cells. Disposable Soma  Preferential allocation of energy resources for reproduction rather than maintenance of somatic cells (i.e., cells forming body of organism).  This allocation of energy causes the body to gradually deteriorate with age. Non-Stochastic Theories of Aging Programmed Aging theory  States that the aging process is determined by a biological/genetic clock  Every organism has a physiological lifespan that is highly characteristic for its species Immunological Theory  Decreased immune function in older adults results in: (a) reduced resistance to disease (b) greater incidence of autoimmune disorders Evolutionary Theories Of Aging Antagonistic Pleiotrophy  Alleles with beneficial effects at young ages may have deleterious effects in later life.  e.g., in humans the p53 gene directs damaged cells to stop reproducing or die.  This helps prevent cancer in younger people, but may be partly responsible for aging by impairing the body’s ability to renew deteriorating tissues.  Thus, altering genes to improve late-life fitness could have a detrimental effect on health at younger ages. Mutation Accumulation  Over evolutionary time, late-acting mutations accumulate at a much faster rate than early-acting mutations.  These late-acting mutations will thus lead to declining viability and/or fertility
More Less

Related notes for GRT2111

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.