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Chapter 5

SOC375 Chapter Notes - Chapter 5: Cardiac Output, Stress Management, High Tech

Course Code
Kwame Boadu

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Chapter 5- Personal Health and Illness
- Maximum life span- the maximum number of years a member of a species can live
o Scientists think the maximum human life span of somewhere between 110 and 125 years has stayed the same for
the past 100,000 years
o Thee is o ko eat figue fo this oept ut it’s ofte take to e the ea life spa of the ost log-lived
10% of a given cohort
- Life expectancy- the number of years at birth an average member of a population can expect to live
o Human life expectancy at birth has increased in the past 2,000 years from an average of 22 years in ancient Rome
to around 75-80 years today
o Varies by region and even within a population of one country has improved considerably in most nations
o Women have gained more in life expectancy than men in the past century
o Technology and biomedical science continue to extend life expectancy, and if this trend continues, more and more
people will live close to the maximum human life span
- Study of personal health and illness has 2 goals to understand changes in the body that come with age and to apply this
knowledge to extend and improve human life
Biological Aging
- The gradual and progressive decay in physical function that begins in adulthood and ends in death in virtually all animal
- Biologists and physiologists distinguish between 2 types of aging:
o Intrinsic aging- changes within the body due to normal wear and tear, genetic mutation, and other internal
sources of change including a decrease in lung capacity, hardening of the arteries, and arthritis
Four criteria for intrinsic (or true) aging:
It takes place in all members of a species
It’s asi to the ogais
It’s pogessie
It leads to decline in physical function increases risk of illness/death
These criteria describe senescence normal decline that takes place in the body over time
Olde people ae at highe isk of illess ad death as the od’s futioal apait delies
Genetics and the influence of the environment (ex. exposure to the sun) will lead to faster/slower decline
o Extrinsic aging- changes due to external circumstances, including the effects of smoking, sunlight, and noise
Theories of Biological Aging
- Biological theories often reflect the methods scientists use in their studies and their field of research
- 2 types of theories exist:
o Programmed theories
Look to the atio of a peso’s gees to fid the soue of agig the same processes that promote
growth and health also lead to senescence and death
View aging as a normal part of growth and development link senescence to growth, development, and
the od’s oal futios
Programmed senescence (Hayflick and Moorehead)
Found that cell division has limits and these limits differ for different species
o Hayflick limit- refers to the number of cell divisions a cell can undergo in an organism
before the cell dies; this limit differs for different species
Based on these findings, they estimated the human life span at 110-120 years
Went further in their research; looked inside the cell to see why cell division stopped
o Phase III phenomenon- studies found that cells took longer to double in number, debris
accumulated in the cells, the cells gradually stopped dividing, and in the end the cells
Related to less production of energy and slower production of enzymes in the
cells allows waste to pile up
Recent research looks at the molecular and genetic structure of the cell to understand the
Hayflick limit
o Foud a elatioship etee teloee shoteig and the aging of cells
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Telomeres exist as a repeated series of nucleotide bases at the ends of
chromosomes and play a role in the replication and stability of the
When cells divide, some of the telomere gets removed, and the cell then loses
the protective effect that the telomere provides
Gradual erosion of telomeres is believed to be the primary factor of the
Hayflick limit
o The accumulation of cells in the body that can no longer replicate leads to loss of
function, and ultimately death
Another genetic process, apoptosis, also plays a role in limiting cell division
o Apoptosis- this poess sithes off the ell’s ailit to diide; eal i life this poess
controls growth and produces normal development, but it leads to cell death and
breakdown in the body over time
o Plays a part in muscle loss in later life
Sarcopenia- loss of muscle mass and function in later life
Some genes serve a positive function early in life, but damage the system later (pleiotropic
genes); scientists refer to this as antagonistic pleiotropy
o Ex. calcium useful for growth and development early in life but can create deposits in
arteries later in life
Endocrine and immunological theory
Glands in the endocrine system secrete hormones into the blood; these hormones act on
specific sites in the body
o Endocrine system controls growth, metabolism, reproduction, and stress response;
responds to internal and external changes in the body
o Sex hormones decrease with age; timing of hormonal release and the responsiveness of
tissues also declines with age
Lead to changes in sexual response
o Adrenal glands produce androgens and estrogens that produce secondary sex
characteristics; these hormone secretions decline with age too
o Pituitary gland stops producing hormones to stimulate the ovaries at about age 55
(starts the process of menopause)
Immune system also ages (as early as age 20) T and B cells play the most important role in its
adaptive function over time
o Each of these cells has a receptor that identifies a foreign substance (antigen)
o B cells secrete antibodies that inactivate pathogens in the blood; if a pathogen enters
the cell from the blood, the T cells take over and attack the antigen
o T ells ill oe up agaist the Haflik liit; the’ll eoe seeset ad uale to
reproduce beyond a certain point deeases the od’s ailit to esist attak
o The decline in T cells from the thymus gland and their decline in function lead to a
reduced ability to fight infection and disease
o Error theories
View aging as a by-product of errors/mistakes within the body
Some of these errors come about through normal cell function; others from external sources
In both cases, errors lead to a decline in cellular and physical function
Somatic mutation theory
Mutation theories link aging to mistakes that take place in the synthesis of proteins
DNA, RNA, and proteins face constant attack from inside and outside the body (ex. radiation
from X-rays, chemicals in the body)
o Damage to DNA can lead to mutations when the cell divides can lead to changes in
mRNA and in turn to damaged proteins
o Large number of defective proteins would lead to cell and tissue death
Cross-linking theory
Long-term exposure of proteins to glucose molecules leads to glycation- the binding of a sugar
molecule to a protein
o This, in turn, leads to cross-linking- the binding of proteins to one another
o This processes increases with age
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o Cross-links toughen tissue and cause some of the damage associated with aging
(including stiffened connective tissue, hardened arteries, and loss of nerve and kidney
o Foreign chemicals can also create links between DNA strands which may stop strands
from dividing (ex. pollutants)
The body does have a way to combat cross-links
o Macrophages- cells that seek out glucose molecules, engulf them, destroy them, and
send them to the kidneys for elimination
o This defence breaks down with age as kidney function declines and macrophages
become less active cross-links increase over time
Accumulation of cross-links leads to physical system breakdown
Medicine may one day be able to prevent this process
Free radicals theory
Oxygen poses a paradox we need it to live, but it can also damage cells/their contents
Free radicals due to oxygen production in the body serve as one source of damage that leads to
o Free radicals- molecules that have an unpaired electron, a large amount of free energy,
and a tendency to bond with other molecules; these molecules can damage tissues and
other molecules (such as DNA, RNA, and cell proteins)
Normal cell metabolism produces free radicals
o Cells in the heart, brain, and skeleton face a high risk of free radical damage because of
the oxygen in their environment
Free radicals act in 3 phases:
o Body produces free radicals in the course of metabolism, and an extra electron gets
attached to molecular oxygen
o They then roam through the body and take an extra electron from another molecule
creates a new free radical
This chain reaction produces harmful chemicals in the body
o Free radicals react with molecules like DNA or RNA ends the process but damages the
Free radical damage to DNA increases rapidly with age can lead to diseases such as late-onset
diabetes, arthritis, cataracts, hypertension, etc.
Ca also daage poteis hih auses a hage i the potei’s stutue makes it unable to
perform its function
o Repair systems in older cells become less efficient, and older cells produce fewer
Antioxidants- chemicals in the body that bind and neutralize free radicals (ex.
nutrients, vitamins C and E, some enzymes, etc.)
Can lead to an accumulation of chemical by-products in the cell
o Create large fatty molecules lipofuscin
As lipofusi takes up oo i the ell, it a itefee ith the ell’s ailit to
create enzymes, release energy, and get rid of wastes leads to more sluggish
Blocks cell reproduction and leads to cell death
o Other theories
These approaches explain aging through population dynamics, the life history of the organism, and the
theory of natural selection
Molecular genetics and the life course
Looks at the mutual impact of genetics and the environment (ex. poverty/malnutrition)
o Expression of the genome is dynamic and changes in response to socially situated
3 models of interaction between the environment and genetic processes:
o Sensitive period model- highlights the effect of the environment on the individual at
critical points of development
Ex. poor nutrition in childhood can lead to poor bone development which can
lead to frailty in old age
o Accumulation model- deficits early in life can lead to cumulative disadvantage
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