Unit 7 - Introduction to Aging Flashcards
how is aging related to disease?
overall progressive impairment of organ/tissue function, which predisposes to disease
- physiological process after reproductive phase of life, whose ultimate consequence is death
- but NOT a disease
what is sarcopenia? is it aging?
it is not aging, but a progressive loss of skeletal muscle mass from 1.5 to 1% per year after age 25
-aging “process” that causes frailty, but not necessarily disease and death
what is the Gompertz law of human mortality?
death rate increases exponentially with age in a protected environment, where external causes of death (famine, disease) are negligible
- after age of mid-20s, probability of dying doubles every 8 years
- shows mean lifespan (age at which 50% of population has died) and max lifespan (age at which oldest known member of a species has died, or mean lifespan of most long-lived 10% of the population)
how is life expectancy calculated?
average number of hears of life remaining in a given age, and uses number of births to calculate
-life expectancy is decreased due to childhood death and aging
what is the more accepted of the “programmed” theory of aging?
aging and death result from a decline in the force of natural selection on traits acting in late life
- so genes that have ill effeccts only at a later age are not exposed to presence of natural selection (b/c prior to reproductive age)
- thus the principal determinant in evolution of longevity is level of extrinsic mortality
what is the mutation accumulation theory of aging?
due to the extrinsic mortality and rarity of aged animals in a natural population, the force of selection is too weak to oppose accumulation of germ line mutations with late-acting deleterious effects
-“selection shadow” allows for a wide range of alleles with late deleterious effects to accumulate over generations with little or no check (dementia, osteoporosis, cataracts, etc.)
what is the disposal soma theory of aging?
somatic organism is maintained only for reproductive success, and that the soma becomes disposable after that
- limited amount of metabolic recourses that have to be divided between reproductive activities and maintenance of non-reproductive aspects of organism
- aging is the result of natural accumulation of damage, that can be repaired by organism at expense of reproductive effort (IOW: longevity has its cost)
what is lifespan determined by?
balance of resources invested in longevity VS reproductive fitness in a specific natural environment
- carries evolutionary trade-off that reduces reproductive fitness
- function of reproductive strategies in a specific environment
- shaped as a result of selective pressures to optimize reproductive fitness of organisms that die from predation and environmental hazards in specific environments
what does evolution act to do, and when is the longevity trait chosen for?
evolution primarily maximizes reproductive fitness, and longevity is only selected for if it’s beneficial for reproductive success
what is the antagonistic pleiotropy theory of aging?
some genes may be selected for beneficial effects on reproductive and survival successes early in life, but the same genes have unselected deleterious effects with age, which contribute directly to aging
- so if extrinsic hazards are high, investment in reproductive success becomes high, and deleterious genes accumulate at earlier ages, so there is a short life expectancy, and vice versa
- best example: rats (4 year lifespan; high reproduction) VS naked molerats (30 year lifespan; higher soma maintenance)
what is compression of morbidity?
age-associated diseases are compressed in last 5% of life
- slowing down aging process may delay onset of aging-related degenerative disorders
- may improve “healthspan”
what is one known way to increase healthspan?
in people with early onset degenerative diseases
-manipulating aging process could be used to treat this disease to extend BOTH lifespan and healthspan
what are the 9 hallmark/theories of aging?
- genome instability
- telomere attrition
- epigenetic alterations
- proteostatic stress
- deregulated nutrient sensing
- mitochondrial dysfunction
- cellular senescence
- stem cell exhaustion
- altered intercellular communication
what does the free radical (oxidative stress) theory of aging require to be valid?
- oxidative damage increases with size
- extended lifespan should correlate with attenuated age-related oxidative damage
- genetic or nutritional manipulations that increase oxidative stress should shorten lifespan and those reducing ROS production should extend lifespan
what happens in animals that are deficient in, or overexpress antioxidant enzymes?
don’t support oxidative stress theory of aging
-they have no shortened or increased lifespan, even though all the activity increased/decreased