Age Related Changes Flashcards
what is aging
a decline in homeostasis that affects all of our systems and tissues
what can most age related change be attributed to
consequence of lifestyle choices
- lack of physical activity most impactful
what is adaptive homeostasis
extent to which body can adapt to physiological stressors and maintain homeostasis influences susceptibility to illness and injury
what is homeostasis
physiological processes that maintain a stable internal environment of the body
- internal thermostat
what is the significance of adaptive homeostasis
ability to adapt to stressors is what keeps you healthy
- this ability dec w age
decline contributes to inc incidence in dz development in older pop
what is physical stress theory (PST)
changes in relative level of physical stress causes a predictable adaptive response in all biological tissue
ability to improve tolerance for physiological stress and provide a wider homeostasis window is possible using PST principles
what impact does successful vs unsuccessful aging have on PST principles
successful:
- can maintain high capacity to tolerate physiological stress
unsuccessful:
- has a low tolerance to physiological stressors
what inc the tolerance range per PST principles
exercises
what dec the tolerance range per PST principles (2)
inactivity
disease
describe the impact exercise has on a healthy aging adult per PST principles
robust positive changes w systemic adaptation
- strength + balance inc
- aerobic endurance inc
- ms endurance inc
describe the impact that exercise has on the inactive aging adult w a stable chronic dz per PST principles
positive changes but at a lesser magnitude than if they were healthy
what does greater physiological reserve and resilience mean per PST
capacity of body to draw on a “well” of immune function, strength, and endurance among other resources
how can a wider window of homeostasis result in a greater chance of survival per PST principles
- wider window of homeostasis
- greater tolerance to physiological stress
- higher ability to maintain independence in physical function
- greater physiological reserve and resilience
- greater chance of survival
skeletal system is susceptible to change in response to which factors (5)
nutrition
activity/inactivity
WBing
hormones
meds
when is peak bone mass reached
skeletal maturity (20-30yo)
skeletal decline in men vs women after peak bone mass
progressive and slow
women:
- post menopause bone loss is most severe likely d/t drop in ovarian estrogen production
men:
- bone loss typically begins after 75yo
what hormone(s) are critical for maintenance of bone mass in both men and women and what is the implication of this
estrogen!
in men: testosterone and estrogen are independent mediators of bone health
any condition affecting sex hormones automatically impacts skeletal health
what direct association explains the significance of skeletal changes as we age
direct association b/w structure and function
what is an example of how structure and function are directly related
joint mobility is directly influenced by changes in any of the related tissues
what are the molecular changes occurring w age in connective tissue (3)
change in integrity by:
- inc structural protein cross-linkages
- dec proteoglycan size
- fragmentation of collagen
what are the cellular changes occurring w age in connective tissue (4)
dec proliferation
altered control of apoptosis
dec response to growth factors
altered response to loading
how do connective tissue structures change with age overall (4)
inc stiffness
dec water content
dec strength
dec cross-sectional area and volume
what are the 4 main total joint changes with aging
dec joint space
inc laxity
altered dispersion of loads -> altered joint mvmts of force
why is altered dispersion of loads skeletally likely seen with aging
d/t dec water content
how are joint mvmts of force altered with aging
unloading of surrounding tissues and joint structures that provide tensile support b/c of dec joint space may predispose joint to dec ROM
what are 5 physiological changes that happen to ms w aging
changes in ms fiber atrophy
changes in ms fiber type
- more slow twitch than fast
contractile function
ms structure
composition
what do aging physiological changes in the ms impact and what is the implication of this
impacts:
- physical performance
- velocity
- force
- strength of mvmt
potentially leads to functional disability
median decline in ms mass throughout lifetime in men vs women
accelerates >75yo
men lose ms mass at a higher rate (.47 vs .37)
- and at a higher accelerated rate >75yo (.8 to .98 per year vs .64 to .7 per year)
what percent decrease in ms mass by 70yo
20-40%
what are 5 significant ms changes with aging
- sig dec in ms fiber size at cellular level
- sig changes in ms fiber composition
- sig dec in absolute and relative contractile skeletal ms content in both males and females
- higher levels of intermuscular adipose tissue
- age related low grade chronic inflammation
how does ms fiber composition change with aging
dec in type 2 fibers
- related to strength and power –> needed to rise from a chair or lift heavy loads
what is the impact of there being a significant reduction in contractile skeletal ms content
dec force per unit area of skeletal ms
what are higher levels intermuscular adipose tissue associated with
dec in physical performance and limited mobility in older adults
what are age related low grade chronic inflammation in muscles associated with
pathological remodeling of skeletal ms
- contributes to dec ms function
what cellular changes are happening d/t age related low grade chronic inflammation in muscles
higher cytokine levels
- associated w lower ms mass and overall strength and physical decline among older adults
what is sarcopenia
loss of ms mass and:
- loss of ms strength
- dec rate of force development
- dec ms power
what does sarcopenia contribute to (3)
deficits in mobility
decline in functional capacity
dec in skeletal ms oxidative capacity
what does a combo of ms impairments and greater fat mass inc the risk of
falling
frailty
development of comorbid conditions (DM2)
what is an inherent aspect of aging in the neurologic system
slowing of nervous system
what have NCS found in older adults w regard to the neurologic system
found lower conduction velocities in peripheral nervous system
what is a motor unit
basic functional unit in the NM system
- allows for production of ms force and mvmt performance
what is a motor unit comprised of and what are the impacts of this
consists of alpha motor neurons and ms they innervate
what are 5 age related changes happening to a motor unit
- loss of motor units
- changes in morphology and properties of motor units
- altered input from nervous system
- denervation
- dec in rate coding (action potential firing rates)
what does altered input from the nervous system to the motor unit impact d/t aging
power
strength
ms endurance
what does denervation d/t aging impact (2)
motor unit recruitment
dec fine motor control
what does a dec in rate coding in motor units d/t aging alter
alters power production and ms contraction speed
what is a major clinical manifestation of a slowing nervous system in aging adults
slowing of mvmt speed
what is the hallmark of aging in peripheral neurologic system
slowing of reflex responses
what is the slowing of reflex responses d/t in the aging adult
declines in density of unmyelinated and myelinated neurons
-> impacts afferent axon potential conduction velocity
where does most slowing of the neurologic system occur and what does this mean
most occurs centrally
- sloughing of myelin has been seen in peripheral nerves –> this slows conduction velocity
what is neuronal atrophy
dec in ~40% in volume/size by 80yo
ms weakness not entirely explained by ms atrophy, also d/t impaired communication b/w brain and skeletal ms
why is parasympathetic and sympathetic nervous system output altered in the aging adult
neuronal atrophy
axonal degen
what are the impacts of age related changes in the parasympathetic and sympathetic nervous system (4)
slowing gastric motility
issues w bladder control
hyper- and hypotension
deficits in circulation
how is sensation to the neurologic system altered with aging
somatic sensory input is altered
what is the implication of it being common for aging adults to complain of vague somatic sx in one part of body
can represent an unrelated event
- challenging for PTs to discern what the cause is in older pts (harder than a vague complaint in younger kids)
when do integumentary related impairments typically occur during aging
when extrinsic stresses combined w presence of comorbidities are added to aging
ex: stress to skin d/t immobility and incontinence inc risk for pressure injury
what is a note about skin changes with aging
changes don’t typically cross threshold of impairment
what are the 2 skin layers comprising the basement membrane
epidermis
dermis
epidermis: what is it, 5 functions, lifespan of epidermal cells and why
thin outermost layer of skin with 5 sublayers
- thermoregulation
- sensation
- moisture elimination
- vitamin D synthesis
- protection of deeper structures
epidermis regens every 4-6wks
- doesn’t have blood supply
dermis: what is it, function, composition and importance of composition
thick, deeper layer of skin responsible for structural integrity of integument
nutrition, hydration, and oxygen to epidermis via diffusion
composed of collagen protein and elastin
- provides tensile strength and allows skin to stretch
how does the epidermis change with age and how does this impact its function
thins and dec in density of Langerhans cells (which initiate immune response when foreign cells are present)
= dec thickness and immune function
–> less efficacy w protection of body from infection and dehydration
how does the basement membrane composition change with age and what are the implications of this
composed of many projections (rete pegs) and provide resistance to shearing forces
thins w age bc of flattening of rete pegs
-> inc vulnerability to shear related insults to skin
how does the dermis change with age and what are the implications of this
thins w age
fewer blood vessels and nerve endings
more prone to hemorrhage
- often site of skin tears
dec perception of light touch and pressure sensation
