Aging (18) Flashcards
Are there reliable biomarkers for aging?
No…the best way to measure age is chronological age.
Usually measure the deather rate and the span of life at the population level
What is the Gompertz law of human mortality?
Death rate increases exponentially with age in a protected environment where external causes of death become negligable
What is mean lifespan defined as?
Age at which 50% of the members in a cohort have died
What is maximum lifespan?
Defined as age which oldest known member of a species has died (longest lived 10% of a population)
What is the programmed theory of aging?
Evolution selected genes for aging, to limit population size and to survive with limited resources
What is the mutation accumulation theory of aging?
Aging is a matter of neglect…random accumulation of alleles with late deletorious effects to accumulate over the generations with little or no effect
What is the antagonistic pleiotropy theory or aging?
Aging is a reflection of imperfection.
Some genes are selected for beneficial effects on reproductive and survival success early in life are not so good for later in life
What is the disposal soma theory of aging?
Age is a matter of resource allocation. Aging is driven by reduced soma maintenance and repair, as a trade-off of reproductive success
What is a method to delaying the aging process?
Increasing healthspan time…slowing down the aging process may delay the onset of aging related degenerative disorders (“compression of morbidity”
What are the 9 major hallmarks of aging?
1- genomic instability
2- telomere attrition
3- epigenetic alterations
4- proteostatic stress
5- deregulated nutrient sensing
6- mitochondrial dysfunction
7- cellular senscence
8- Stem cell exhaustion
9- altered intercellular communications
What does the free radical theory of aging predict?
That toxic byproducts of metabolism can damage cell components…notably the hydroxyl radical
What is the supportive evidence of free radical theory of aging?
Proven damage to DNA, lipids and proteins
Increase in abnormal mitochondrial with age
Acceleration of age with ionizing radiation
Why is the free radical theory of aging being challenged?
Because animals deficient in or overexpressing antioxidant enzymes do not generally have a longer lifespan
Naked more rats (live longer) have higher, rather than lower oxidative stress
What are the effects of mitochondrial dysfunction?
Energy depletion
Increased the propensity of mitochondrial permeability in response to stress…so there is an increase in apoptotic or necrotic cell death
Defective iron-sulfer biosynthesis…affects nuclear genome stability
Alters redox and ROS signaling
Affects global protein homeostasis
What is the cell senscence/ telomere shortening theory of aging?
Most somatic cells do not express telomerase and when telomeres get too short a double strand DNA break like DNA damage response is triggered and cells enter into senescence
