Aging Flashcards
What is the general vs specific view of aging?
General view: aging is the sum of all structural / functional changes occurring over time
Specific view: post-maturational period of decline in health (senesence), ultimately resulting in death
What generally causes cellular aging?
Progressive decline in cellular function due to accumulation of cellular / molecular damage, especially genetic abnormalities
What organism is ageless?
Bacteria
On a survival curve, what is the maximum life span potential?
The time at which the last individual in the population dies (0% survival)
What does life expectancy mean on a survival curve?
50% or median survival of a population / cohort
What are the two shapes of survival curves, and which one do humans exhibit?
- Exponential decline -> due to constant environmental hazards, a constant fraction dies overtime. Characteristic of “the wild”
- Sigmoid decline -> diminishment of environmental hazards, characteristic of non-wild conditions (fraction dying changes overtime). This is a property of civilization = humans exhibit this. Shows the phenomenon of aging.
Have LE and MLSP changed significantly overtime? Why?
LE - has increased. The median survival has grown higher and higher. This is thought to be a product of reduction in environmental hazards.
MLSP - seems to be intrinsic and based on senescence, has not changed overtime. Even 2000 years ago, there were some elders who lived as long as our oldest people. (species-specific).
What is the mode of inheritance of Hutchinson-Guilford syndrome, what is it also called, and what is the nature of the defect?
Infantile progeria syndrome -> defect in lamin A gene, a nuclear membrane protein.
Autosomal recessive
Average life expectancy is about 12 years
What is the mode of inheritance of Werner syndrome, what is it also called, and what is the nature of the defect?
Adult progeria syndrome
-> defect in DNA helicase gene, involved in DNA repair and recombination
Autosomal recessive
Average life expectancy is about 40 years
Are progeria syndromes identical to normal aging?
No, there are a lot of other pathological processes going on, but certainly there are shared features.
What did the Hayflick experiments demonstrate?
The number of doublings of fibroblast-like cells is finite, and is followed by deterioration.
Organisms with greater possible fibroblast doublings tended to have a longer lifespan
After about how many divisions are telomeres lost?
~50
What are sirtuins and what are a few of their functions?
NAD-dependent protein deacetylases
Function in DNA repair, gene expression, apoptosis, and aging
-> have a protect effect against DNA damage via deacetylation of proteins which are active to cause DNA dysfunction
What is the mechanistic basis for dietary caloric restriction reducing certain age-related diseases?
A reduction in oxidative metabolism reduces the rate of oxidative / free radical damage
- > longevity
- > some theory that we may have a maximum lifetime energy usage allowance
What piece of evidence seems to imply that acquiring, processing, and transmitting knowledge is useful to overall survival of the species?
Brain size directly correlates with longevity
What do genomic mechanisms of aging suggest?
Specific aging genes, including genes which control cell doubling (telomerase), apoptosis, and gene regulation sirtuins, control the ultimate senescence of the organism.
What is the somatic mutations theory?
A wear and tear mechanism of aging, which suggests that cumulative DNA damage from processes such as radiation or chronic insult leads to impairment of cell / organism survival.
What are wear and tears mechanisms of aging?
Aging occurs through the accumulation of damage due to random events, i.e. free radicals, glycosylation, etc
What are the regulatory system mechanisms of aging based on?
Aging occurs due to dysfunction in one of the major organ systems, which acts as sort of biological clock
What is the immunologic system theory?
Changes in immune system lead to abnormal immune function, increasing incidence of autoimmune disease and neoplasms
-> form of regulatory system mechanism
What is the neuroendocrine model of aging?
HPA axis controls aging, based on the idea that puberty is on a biological clock
-> thus far, the “pacemaker” or “timekeeper” is yet to have been found.
Based on the rate of living / metabolic energy theory, what governs how long you live?
Lifespan energy potential (LEP) -> MLSP is proportional to the amount of energy which can be consumed by the organism during its lifetime
What is an age-related vs age-dependent disease?
Age-related = increases in frequency with aging, but not directly caused by it
Age-dependent = diseases related directly to effects of age / chronic exposures
What are some age-related diseases?
Atherosclerosis / CVD, septicemia, pnuemonia, cancers, Alzheimer’s and Parkinson’s
