Health Sciences 2711A/B Lecture Notes - Lecture 3: Activity Theory, Calorie, Thymus
27 Jun 2018
School
Department
Course
Professor
Theories of Aging
Theory: the construction of explicit explanations in accounting for empirical findings
makes sense of WHY behind what was observed in research
Used to build understanding (knowledge) in systematic and cumulative way
guides for future research
must be able to be disproven
theory comes from observations
Why do we Need Thories?
Good Theory links intervention to outcomes
What works best in different situaitons
allows selection of best action for predicted outcome
Helps with prediction in new circumstances
guides professional practice
Theory -> RCTs -> Best practice guidelines
if you don’t understand the problem how can you fix it?
If we didn’t have a theory we can’t follow what’s systematically known about it to be
able to fix it
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Cellular: 1. programmed cell death, 2. waste product there, 3. cross linkage theory
1. Cells have an intrinsic fixed limited capacity to divide therefore aging process is
controlled by cellular clocj
2. Many human cell systems accumulate the age pigment lipofuscin which is believed to
disrupt cell metabolism and cause aging
3. Irreversible covalent cross-linking of DNA molecules leads to cellular dysfunction and
aging
Physiological theoreis: 1. Exhaustion of irreplaceable supplies, 2. decline in K and less
gluthione
1. With aging body, water composition declines 30% loss of sodium and consequential
loss of potassium is blamed for it
2. supplies of glutathione (anti-oxidant in human lens) decrease literally with age and
can’t be replaced from elsewhere in the body
This is how we age due to resources being depleted
Organ Based Theories: 1. Immune Theories, 2. Calorie Restriction, 3. Neuro-endocrine
Theories
1. Atrophy of thymus gland with age decreases immune system efficiency leading to
infections, autoimmune disease and cancer
2. Eat less live longer - calorie restricted diet increases a person’s lifespan
Biosphere 1 and biosphere 2
rats with lower caloric intake in diet reproduced less because compensating
reproduction than survival
is there an optimal amount of calories that allow us to live longer?
3. reductions in number of neuro - endocrine cells leads to aging
20% smaller brain at age 90 compared to over lifetime
neurons has a pacemakers that determines biological clock
Genetic Theories:
A. Programmed
1. Aging is a result of a pre-written program that controls growth, development and aging
2. certain genes are suppressed until achievement of reproductive potential
3. genes beneficial in early life become harmful later in the lifespan
4. aging is caused by prevailing loss of non-repeated information the genome
large increase in reoccurring DNA would increase longevity
B Un-programmed: best theory
1. Radiation causes genetic mutations that lead to cellular dysfunction and death
2. Ability to repair somatic mutations is directly correlated with lifespan potential
3. random errors in synthesis of proteins lead to accumulation of defective DNA
4. Molecules of ionized oxygen (have one extra electrion) readily bond with proteins
preventing them to carry on their functions
Free radicals - naturally occurring highly reactive chemicals that form in the
presence of oxygen and cause damage to protein and DNA
5. Telomeres - repetitive DNA sequences at the end of chromosomes are progressively
shortened
telomeres is also shortening
Bio - Theories - summary
all in genes - aging is controlled at the most basic level of organic life (DNA)
Disease and senescence are the product of natural selection through evolution
Each species has a max lifespan - it is genetically determined
biomarkers - 24 distinct physiological functions that declines with age
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Document Summary
Theory: the construction of explicit explanations in accounting for empirical ndings makes sense of why behind what was observed in research. Used to build understanding (knowledge) in systematic and cumulative way guides for future research must be able to be disproven theory comes from observations. What works best in di erent situaitons allows selection of best action for predicted outcome. Helps with prediction in new circumstances guides professional practice. If we didn"t have a theory we can"t follow what"s systematically known about it to be able to x it. This is how we age due to resources being depleted. Theories: atrophy of thymus gland with age decreases immune system e ciency leading to infections, autoimmune disease and cancer, eat less live longer - calorie restricted diet increases a person"s lifespan. 20% smaller brain at age 90 compared to over lifetime neurons has a pacemakers that determines biological clock.
