lecture 1 Flashcards
what is the definition of aging?
The time-dependent changes in a living organism
What is the definition of senescence?
the gradual deterioration of function that results in an increase in mortality of the organism
cellular senescence
cells no longer divide
definition of longevity?
the typical length of life for a species, this term is sometimes synonymous to life-expectancy
what is geroscience?
biology of aging and age related diseases
what did George Williams study?
Pleiotropy, natural selection, and the evolution of senescence
Antagonistic pleiotropy
- George Williams
-postulates that certain genes might have opposite effects on fitness at different ages
**something beneficial early in life is harmful at post-reproductive age
what is an example of antagonistic pleiotropy?
high testosterone levels
-benefit reproduction
-increase late life risk of prostate cancer
Mitochondrial DNA activity
-MtDNA is very important in early active stages of life
-but increases in activity in mitochondria when you are younger makes for issues later in life
Disposable Soma
energy is required for:
-metabolism
-reproduction
-repair and maintenance
Thomas Kirkwood believed that because metabolism and reproduction were the major focus of an organism(greater priority), so the repair and maintenance did not receive enough emphasis and so there is a gradual deterioration
supply of food is finite– the body must compromise
what is the explanation behind the disposable soma theory?
aging results from this accumulation of unrepaired cellular and molecular damage
longevity is controlled by the genes that regulates maintenance and repair
also, different types of damage contribute to aging= meaning that it is a complex network
what are the top leading causes of death in canada 2020?
malignant neoplasms (cancerous tumors) are number 1
diseases of the heart are 2nd
Risk for covid-19 infection, hospitalization and death by age group diagram
ages 18-29 were selected as the reference group because it accounted for the largest cumulative number of COVID-19 cases compared to other groups
-rate of death is 4x higher in ages 30-39, 330x higher in those who are 85+
-hospitalizations and deaths as age increased had a higher rate when compared to the reference age group
the cost of a long life
The United States spends the most per capita on health care - yet they do not have the highest average lifespan
-Japan has the highest average life spans
as of 2020, the average lifespan for Canada is 81.75 so approx. 82. For Japan it was 84.62, and for the US was 77.28.
-The US was seen as the outlier cause they spent so much, yet had a life expectancy of around 78 while Japan was around 82
labor income and consumption
people age out and do not work anymore and this affects the economy
-consumption continues to rise while labor income is shaped like a bell curve, at a certain age it declines
chronic diseases- US based
heart disease and stroke = kills the most people, cost the healthcare system the most
cancer= second leading cause of death
diabetes, obesity, arthritis, Alzheimer’s disease, epilepsy and cavities
cavities (tooth decay) is one of the most common diseases in the united states
Life expectancy in the United states
- has had a general increase which is very good
- in 1918 there was a plummet because of the Spanish Flu, H1 N1
in 2020, there was a minor decrease in life expectancy accounted for because of covid-19
life expectancy at birth, by sex 2000-2020
- trends seen are that women live longer than men, and this is seen in mammalian groups as well
-this graph also accounted for a minor dip in 2020 due to covid-19
lifespan (laboratory mouse)
- there are some genetic predispositions to lifespan differences
-not necessarily “anti aging genetics”
-predisposition to disease
-some strains of mice have different life spans, there is even diversity within a strain as well
e.g. Fisher rats are very prone to kidney disease so they are not used as much
there are also environmental factors, diet and other stressors that can affect the results - but most of these can somewhat be controlled in a lab
Squaring the curve
-extending average lifespan, but NOT extending maximum lifespan
-mechanisms of aging need to be identified and modified
longevity increases experiment
control group: 65% calories from carbohydrates
LCD ( low carbohydrate): 70% calories from fat
KD (Ketogenic diet): 89% calories from fat
-minor increases, low carb group lived slightly longer
Healthy aging
- hand grip strength males and females 50+
declines across both males and females as age increases
also in weightlifting: there are sex differences and age too - women have a much more significant decline
powerlifting: for sure age declines, but men and women are very similar so not much sex difference
For aging studies, what system or organism?
humans?
long-lived species?
species with unusual lifespans?
short-lived species like Drosophila, C. elegans
Rodents
-many strains, and transgenics available
cells
-yeast, cell culture
slow aging organisms
giant tortoise, tuatara, rockfish, cockatoo, bowhead whale
organisms age differently : rapid?
yeast, nematode, fruitfly, bamboo
