The Biologic Basis of Aging Lecture Powerpoint Flashcards
Elderly age group
Those 65 and over
Gerontology vs geriatrics
Gerontology involves the social, psychologic, and biomedical study of aging and ALL aspects associated with it (includes social workers, etc) while geriatrics is a medical specialty
Aging definition
Deteriorative process beginning after maturity resulting in decreased viability and increased vulnerability
Senescence
Aging process at the cellular and organismal levels during the latter part of the life span (last 20%)
Life expectancy
Average lifespan of a specific population (location, gender, age, etc - remember the life expectancy for an individual age 80 is greater than those of age 10 because they have already survived all the car wrecks and such), at birth is 78.7 years overall
Female vs male life expectancy
females 81.2 years while male is 76.2 years
Maximum human lifespan
longest an individual has lived within a given population or species
Life span vs health span
Health span is how long an individual retains their health status and capabilities to live a functional life, a goal of geriatrics is to improve this over necessarily just improving life span
US life expectancy
Has improved in recent years but is not the highest in the world
Why do we age?
No concrete consistent reason known, previously thought to be related to evolution but has been discredited, likely multifactorial between genetics, metabolism, and environment, but ultimately due to a disruption in homeostasis (increase in entropy), primary aging is normal physiologic processes and secondary is acquired diseases throughout life, prevention helps save HUGE costs of healthcare - promote the idea of “healthy aging”
Cardiovascular physiologic changes that occur with aging (5)
- decreased myocytes
- increased collagen
- decreased compliance
- increased systolic pressure/LVH
- decreased maximum heart rate
Pulmonary physiologic changes that occur with aging (3)
- reduced chest wall compliance
- reduced respiratory response to hypoxia
- decreased ciliary function
Presbyopia
Reduced accommodation due to decreased compliance of the lens with age, often resulting in elderly individuals having to hold text further away in order to read
Reduced night vision mech of action
Reduced pupil size naturally during ages results in decreased light entering the eyes and as a result worsened night vision
Neurologic physiologic changes that occur with aging
- decrease in cortical gray matter, complexity of connections, neurotransmitter produciton
- demyelination (slowed conduction)
- reduced reflexes/proprioception
Renal physiologic changes that occur with aging (2)
- decline in renal blood flow approx 10% per decade after 50
- often not noticed until much more advanced
Skin/hair physiologic changes that occur with aging (3)
- loss of pigment in hair
- loss of elastin in skin
- thinning of skin
Pathologic changes of aging (often related to lifestyle) (6)
- CAD/MI/CHF/HTN
- TIA/stroke
- cancer
- COPD
- renal failure
- arthritis
Natural selection theory of aging
Traditional (less scientific) idea that aging and death have been ubiquitous over time, in relative absence of disease, humans still have a maximum lifespan, and this must be because natural selection focuses on selection of favored genetics not how long an organism lives for
Trade-off between somatic maintenance and reproduction theory of aging
Traditional (less scientific) idea that in reproductive years, we invest energy in reproduction and caring for offspring leaving less energy to invest into somatic repair resulting in aging
Why have aging studies often been done in animals?
They have shorter lifespans, a well known genome, and can be manipulated in ways not possible in human studies
Neuroendocrine theory/hypothesis of aging
Modern scientific programmed theorythat there is complex interplay of hormones that regulate vital life functions, but with age hormone levels decline decreasing body’s repair and maintenance systems (ex - IGF-1 role in aging rates)
Thymic stimulating theory/hypothesis of aging
Modern scientific programmed theory that the thymus is the master gland of the immune system (playing a vital role in T cell function) and its size decreases with age resulting in weakening of immune system contributing to aging (birth is 200 g, by age 60 only 3 g)
Telomere (telomerase) theory/hypotehsis of aging
Modern scientific programmed theory (relatively new) that postulates that telomere caps at the ends of chromosomes that do not code but act to maintain chromosomal integrity and as cells divide and chromosomes are copied telomeres are shortened leading to cell damage and death and this leads to aging, telomerase found only in germ or cancer cells could immortalize us
Genetic control theory/hypothesis of aging
Modern scientific programmed theory of planned obsolescence that genetic programming within our DNA contains a biologicla clock set to go off at a predetermined time that when it does signals a cell to age and die, each individual has their own clock and lifestyle can alter it
Hayflick limit theory/hypothesis of aging
Modern scientific programmed theory that derived from experiments demonstrating senescence of cultured human cells and therefore cells are genetically preprogrammed to divide a set number of times (like 40-60) then die, overfed cells divided quicker and died, and that loss of cell leads to aging and death
Autoimmune theory/hypothesis of aging
Modern scientific programmed theory that postulates over time our immune system experiences decline in ability to produce antibodies to fight off disease and ability to differentiate between body’s own cells and dz cells (examples being lupus, scleroderma, cancer, etc) and this leads to damage, aging and ultimately death
The hypothalamus as a control center theory/hypothesis of aging
Modern scientific programmed theory that suggests thru new research the hypothalamus plays fundamental roles in growth, development, repro and metabolism and that age related signaling blocking can slow aging in mice
The wear and tear theory/hypothesis of aging
Modern scientific damage/error theory that suggests the human body is like a machine that wears out due to chronic use and cells are damaged by overuse and abuse or toxins, and that healthy young bodies can repair but with age these systems deteriorate and accumulate
Free radical (oxidative damage) theory/hypothesis of aging
Modern scientific damage/error theory that states free radicals which contain free electrons become destructive in biological systems, attacking and splitting apart other paired electrons, and that free radicals attack cell membranes generating metabolic waste products and also attack collagen, elastin, proteins, DNA’s etc - free radicals are with us from birth produced by metabolic processes similar to rusting of ferrous metals and that antioxidants slow this
Caloric restriction theory/hypothesis of aging
Modern scientific damage/error theory that gradual weight loss to a point of metabolic efficiency results in the maximum health and lifespan (30-40% fewer calories than normal) decrease metabolic activity and therefore free radicals (doing the minimum amount of metabolism to sustain life), high nutrient low calorie diet coupled with moderate supplements and regular exercise (CRON - caloric restriction, optimal nutrition)
The only well researched effective means of reliably slowing the aging process and increasing avg max lifespans in a number of organisms
the caloric restriction theory/hypothesis
Waste accumulation theory/hypothesis of aging
Modern scientific damage/error theory that states that during lifespans cells produce more waste products than can properly eliminate, accumulation causes cells to age and die
Mitochondrial theory/hypothesis of aging
Theory built off the free radical (oxidative damage) theory that states that there is free radical/oxidative damage but in this case specifically focusing on that in the mitochondria, and that ATP genesis produces free radicals that can then attack mitochondria and mtDNA which accumulate damage and decrease ATP production over time
Cross linkage theory/hypothesis of aging
Modern scientific damage/error theory that believes cross linking occurs when older biological systems become incapable of removing excess glucose, so excess glucose promotes glycosylation which affects proteins, DNA, connective tissue in body decreasing elasticity, obstructing movement of nutrients and waste,
Error and repair theory/hypothesis of aging
Modern scientific damage/error theory that states DNA typically has highly effective correcting organisms for errors in the copying of DNA essential for life, replication errors increase with age, repair mechanisms are less effective with age, and accumulation of these errors over time damages or destroys cells
