Physiology of Aging Flashcards
Another name for aging is?
senescence
Is senescence universal?
no
Prokaryotes do not
only multicellular organisms that undergo somatic cell differentiation
Is senescence in humans slowly happening and unavoidable?
yes
Rapid senescence?
deterioration after maturation/ reproduction
invertebrates, annual plants, pacific salmon
Gradual senescence?
slow but persistance senescence
placental mammmals including humans
Negligible senescence?
trees, some reptiles, fish
Stochastic (random error) theory?
a potential cause of aging
Accumulation of random damage
examples of accumulation of random damage?
somatic mutation such as from ionizing radiation, lack of dna repair mechanisms, cross-linking of intra and extracellular matrix components, glycosylation of proteins resulting in inability to perform primary functions, free radical damage
neuroendocrine theory?
holds that degeneration of the hypothalamic-pituitary-endocrine axis is central to aging
evidence of neuroendocrine theory?
growth, onsent of puberty, reproduction, menopause, metabolism
immunologic theory?
based on observations of decline of immune system with age
example of immunologic decline?
decreased t cell response, increased risk of infections, autoimmune responses against self
maybe a secondary aging phenomenon
cellular (replicative) senescence?
finite number of replications
noncoding regions of DNA sequences called telomeres which grow shorter on the end of chromosomes with every replication
telomerase?
enzyme that can maintain telomere length
p53 transcription factor?
blocks proliferation of damaged cells
can some tumors/ malignant cells express telomerase?
yes, enabling them to replicate an infinite number of times
Presbyopia?
increasing stiffness (loss of accomodation) of the lend of the eye
Opacification of the lens
cataracts
results in decreased visual acuity
Antioxidant regimen that may be beneficial in preventing and treating ARMD?
500 mg vit C, 400 IU vit E, 15 mg beta carotene, 80 mg zinc as zinc oxide, 2 mg cupric oxide
Dry macular degeneration vs wet?
less severe
untreatable
prebycusis?
hearing loss of aging
decrease high frequency acuity
results in difficulty hearing to deafness
etiology of prebycusis?
loss of cochlea and auditory nerves not in the middle ear
4 age changes of cardiovascular system?
decrease arterial compliance
decrease beta andrenergic responsiveness
decrease baroreceptor sensitivity
decrease sinus node automaticity
changes in cv system result in?
systolic hypertension
low cardiac output and bp response to stress
impaired bp response to standing and hypovalemia
arrythmias
CHF
Describe the aging heart
loss of myocytes
fibrosis increases
parasympathetic neurons decrase hence use of atropine has less effect on heart effect
sclerosis and calcification of heart valves occur
Describe vascular aging?
irregularities of size and shape of endothelial cells, fragmentation of elastin in internal elastic and media, increased lumen diameter, vessel length, wall thickness, collagen increases, cross linking (esp in subendothelium), decreased basal and stim NO production, increase in systolic and pulse pressure, independent of cholesterol, non-inflammatory, uniform in all large arteries
Most common valve problem?
stenotic aortic valve
Aging impact on Lung function?
lower maximal expiratory flows
lower diffusing capacity
lower P02 and Sp02 as a consequnce of V/Q mismatch
lower respiratory muscle strength and endurance
stiffer chest wall
increase lung tissue compliance (less recoil)
reduced respiratory drive
5 things with aging respiratory system?
decrease lung elasticity decrease rate of diffusion increase chest wall stiffness decrease cough reflex results in: decrease resting p02, increased risk of aspiration and infection
Aging Respiratory impact on individual?
less exercise capacity
higher susceptibility to pulmonary disease
higher incidence of respiratory tract infections
use of cough reflex to clear secretions due to decrease ciliary action
Tooth loss?
dependent on disease (periodontal infections and carries) rather than pure aging process
Aging GI system?
decreased hepatic function decreased gastric acidity decreased colonic mobility decreased sensitivity of taste buds Results in: delayed metabolism of some drugs, constipation, poor appetitie- malnutrition
Taste and eating habits are good indicators of?
aging vs medically compromise
Most changes of function/ structure of upper GI tract in elderly are result of?
path changes secondary to disease not aging alone
Physiology that does not change with age?
esophageal function persists until very advanced age
incidence of reflux is stable but the duration of each reflux episode is longer
gastric emptying of solids remains stable although liquid emptying is prolonged
small bowel transit times remain stable
Aging renal system?
decrease GFR (10 percent per decade after 50)
results in:
delayed clearance of some drugs
decrease in urine concetration/ dilution ability
Kidney mass peak?
4th decade
`
decline in renal function accompanied by?
thickening of basement membrane
messangial expansion
focal glomerulosclerosis
Skin changes in aging?
thinning of epidemis and dermis atrophy of subcutaneous adipose tissue decreased vascularity decreased oil and sweat production results in: bruising, skin tears, pressure sores
Skin lesions?
not normal aging
Eczema?
common
Aging MSK system?
decrease muscle mass decrease bone density results in: decrease strength and endurance osteopenia/ osteoporosis
skeletal scenscence?
decrease bone mass
decrease bone strength
increase risk of fractures
skeletal m aging results in?
limited ability to climb stairs, rise from chair
increase risk of falling
contributes to heat and cold intolerance
rate of decline in skeletal m? (weak vs conditioned)
similar in both, exercise however will produce increased short term endurance
Aging cartilage?
decrease cartilage hydration
smaller proteoglycans, same number, increase cross linking
reduced proliferation of chondrocytes and reduced metabolic activity
Aging brain/ nervous system?
decrease brain size (atrophy) decrease NT, catechol and dopamine decrease righting reflex decrease stage 4 sleep impaired thermal regulation results in: slower speed of memory and calculation stiffer gait increased body sway insomnia lower body temp at rest
Nervous system aging
decreased brain weight decreased cortical cell count neuronal loss decline NT productions loss of synaptic receptors decline cerebral metabolism decline # of mitochondria have been observed in aging synaptic cells
Central, Motor, and Sensory NS
increase motor response time slower pyschomotor performance decrease intellectual performance decrease complex learning decreased hour of REM and total sleep
