Unit 2 - Chaper 3 of Text Flashcards
What is the rate-of-living theory of aging?
- Organisms have only so much energy to expend in one lifetime
- Reducing one’s caloric intake can influence longevity
- The age at which a mammal becomes mature is related to longevity
What is the cellular theory of aging?
- Focuses on the number of times a cell can divide before dying
- Called the Hayflick Limit, after its discoverer
What are the 3 cellular theories of aging?
- The number of times a cell can divide
- Cross-linking
- Free radicals
What are telomeres?
A word used to describe the tips of chromosommes
- They play a major role in aging by adjusting the cell’s response to stress and growth stimulation based on cell divisions and DNA damage
- Healthy, normal telomeres help regulate the cell division and reproduction process
What does the enzyme telomerase needed for?
- Telomerase is needed in DNA replication to fully reproduce the telomeres when cells divide
- Telomerase is not generally present in somatic cells, so with each replication, the telomeres become shorter
- Eventually, the chromosomes become unstable and cannot replicate because the telomeres are too short
How might exercise influence tolomeres?
Exercise may slow the rate at which telomeres shorten, which may help slow the aging process
What is the second cellular theory of aging?
- Based on a process called cross-linking, in which certain proteins in human cells interact randomly and produce molecules that are linked in such a way as to make the body stiffer
- These proteins make up 1/3 of the protein in the body and are called collagen
What purpose does collagen serve?
- Collagen acts like reinforcing rods in concrete
- The more cross-links there are, the stiffer the tissue will be
- Explains why tissue hardens as we age (such as heart and arteries)
What is the third cellular theory of aging?
- Aging is caused by unstable molecules called free radicals
What are free radicals?
- Unstable molecules which are highly reactive chemicals produced randomly in normal metabolism
- Free radicals interact with nearby molecules and problems may result
- For example … free radicals may cause cell damage by changing the oxygen levels in cells
What are antioxidants?
- Prevent oxygen from combining with susceptible moleccules to form free radicals
- Common antioxidants include vitamins A, C, & E, coenzyme Q
- Ingesting antioxidants postpones the appearance of age-related diseases such as cancer, cardiovascular disease, and immune system dysfunction
- No direct evidence that antioxidants increase the life span
What are programmed-cell-death theories?
- Aging may be programmed into our genetic code
- When cell death appears random, researchers believe that such losses may be part of a master genetic program that underlies that aging process
- Programmed-cell-death appears to be a function of physiological processes, the innate ability of cells to self-destruct and the ability of dying cells to trigger key processes in other cells
- Don’t know how the self-destruction process is initiated
What mechanism is thought to underlie programmed cell death?
What diseases/disorders may be examples of programmed-cell-death?
- Osteoporosis
- Alzheimer’s disease
Both have the ability to change brain cells
What are the 3 general research-based approaches to slowing aging?
- Delay chronic illnesses of old age
- Research aimed at slowing the fundamental processes of aging so that the average life span is increased to over 110 years
- Seeking to arrest or even reverse aging, perhaps by removing damage inevitably caused by metabolic proccesses
What 4 developmental forces interact in biological and physiological aging?
1) Biological
2) Psychological
3) Sociocultural
4) Life cycle
What factors account for the changes we see as our skin ages?
1) Wrinkling - skin ges thinner, more fragile, and loses some of its flexibility
2) Ultraviolet rays from the sun which breaks down the skin’s connective tissue
3) Smoking, which restricts the flow of blood to the skin around the lips
How does our hair change as we age?
1) Becomes thinner and loses its colour
2) Hair loss is caused by destruction of the germ centres that produce the hair follicales
3) Colour loss from a cessation of pigment production
How do our voices change as we age?
- Older adults’ voices tend to be thinner or weaker
- Age-related changes in one’s voice include lowering of itch, increased breathlessness and trembling, slower, less precise prronunciation, decreased volume
What changes in body build do we experience as we age?
1) Decrease in height - height remains fairly stable until the 50s, but between the mid-50s and mid-70s men lose 1 inch and women lose 2 inches. Caused by compression of the spine
2) Fluctuations in weight weight gain in middle life is often followed by weight loss in old age. People gain weight between their 20s and 50s and then lose weight through to old age. Older adults who have normal body weight at age 65 have longer life expectancy and lower rates of disability than 65 year olds in other weight categories
What systems are involved in the changes of mobility that aging people experience?
- Muscles and balance
- Bones
- Joints
What changes to muscles and balance do older people experience?
- The amount of muscle tissue declines with age
- At age 70 the loss is about 20%
- At age 80 the loss is about 40
- Muscle endurance diminishes with age but at a slower rate
- As lower body strength declines, the likelihood of balance problems and falls increases, as do oblems with walking
What changes to bones do older adults experience?
- Bone loss begins in the late 30s, accelerates in the 50s and slows down by the 70s
- Women lose bone mass twice as fast as men
- Women have less bone mass than men so they start with less ability to withstand bone loss
- Depletion of estrogen after menopause speeds up bone loss
What happens to aging bones?
- Involves a loss of bone mass inside the bone, which makes bones more hollow
- Bones become porous
- Hollow, porous bones are easier to break - when the break, it tends to be a clean break, which is harder to heal than a splintered break
What is osteoporosis?
- Severe bone degeneration in which the loss of bone mass and increased orosity create bones that resemble laced honeycombs
- People with osteoporosis tend to develop distinct curvature in their spines
- Leading cause of broken bones in older women
- Women do not consume enough dietary calcium to bild strong bones and the decease in esrogen following menopause greatly accelerates bone loss
What are the risk factors for osteoporosis?
- Low bone mass at skeletal maturity
- Deficiencies in calcium and Vitamin D
3) Deficiencies in estrogen
4) Lack of weight bearing exercises
5) Smoking
6) High protein diets
7) Excessive alcohol, caffeine, sodium
8) Some medications for asthma, cancer, rheumatoid arthritis, thyroid problems, epilepsy
What are biophosphonates?
Medication that slows the bone breakdown process by helping to maintain bone density during menopause
What happens with aging joints?
1) Beginning iin the 20s, the protective cartilage in joints shows sins of deterioration, thinning and becoming cracked and frayed
2) The result of tis activity is two types of arthritis:
a) Osteoarthritis
b) Rheumatoid arthritis
What is osteoarthritis?
- Over time the bones underneath the cartilae become damaged, which can result in osteoarthritis, a disease marked by gradual onset and progression of pain and disability, with minor signs of inflammation
- Is a wear-and-tear disease - pain is worse when the joint is used
- Usually affects hands, spine, hips, knees
- Response is steriods, anti-inflammatory drugs, non-stressful exercise, diet
What is rheumatoid arthritis?
1) Destructive disease of the joints that develops slowly and affects different joints and causes pain
2) Morning stiffness
3) Aching develops in the finges, wrists, and ankles
4) Joints swell
5) Therapy is aspirin, some anti-rheumatic drugs
What is arthroplasty?
Total relacement of joints damaged by arthritis
What sorts of factors affect how older people view aging?
1) Can be dismissed as less valuable when one has gray hair, wrinkles … can be translated into perceptions of intellectual ability as well
2) Loss of strength and endurance
3) Loss of muscle coordination
4) Arthritis limiting movement and independence