decreased ability to maintain and recover

Increased tolerance: +tissue adaptation --> excessive stress overwhelming; disease, trauma, illness --> death

Decreased tolerance: deconditioning/frailty --> inability to adapt to even low levels --> death

by 80, 40-50% decrease strength

~8% loss per decade

↓ # motor units

↓ ability activation of existing muscle mass

↓ quantity muscle tissue (type I & II)

↓ force developed by each cross bridge

↓ speed of contraction - POWER

Exercise requires higher max intensity

Must activate larger % of reduced mm mass to generate same power

↓ blood supply/capillary density

impaired glucose transport

↓ mitochondrial density

↓ oxidative enzyme activity

Muscle wasting

Causes weakness, ↓ activity level, ↑ falls, morbidity, and loss of functional autonomy

Low mm mass with EITHER low strength or physical performance

↓ bone mass and density

osteoblast/clast activity imbalance

↓ circulating Ca++ and activated vitamin D3

↓ estrogen levels in women

peak mass age: ~30

↓ amount/quality synovial fluid

change in activity level --> deterioration of articular cartilage

stiffness 2' formation of crosslinks in collagen and loss of elastic fibers

↓ hydration

↑ rigidity of intervertebral discs

↓ CO (=SV x HR)

↓ response to stress

↓ aerobic capacity

↑ Rest BP

↑ Peripheral Vascular Resistance

 Loss of pacemaker cells --> ↓ sensitivity to beta andrenergic stimulation

↓ max HR with exercise

no effect on RHR

blunted reponse to couging, postural changes and Valsalva

↓ Diastolic filling rate - prolonged relaxation time, sclerosis of valves, ↓ L vent compliance

Vascular impedance - central aortic stiffness, increased peripheral vascular resist

Prolonged isometric relaxation

L ventricular wall hypertrophy

↓ response to beta-adrenergic stimulation --> ↓ ionotropic response

↓ baroreceptor sensitivity

Arterial baroreceptor reflex ↓ cuz HTN and aterosclerosis

↓ renin, aldosterone, angiotensin II levels

↑ tone

extra-cellular fluid volume

140/80 new normal ?

↓ HR

↓ EF w/ physical exertion

↓ baroreceptor response, ↓ vascular elasticity --> postural hypotension, especially from supine (SV & CO ↓)

 ↓ VO2 max, 10%/decade

↓ HR & mm mass

Sarcopenia = VERY LOW 

↓ chest wall compliance - calcification of ribs, changes in spinal curvature

↓ lung elastic recoil

↑ work of breathing/energy requirement 

↓ max voluntary vent

↓ max expiratory flow

↓ FEV1

↓ VC and ↑ residual vol while tidal vol remains constant 

↓ efficiency for ventilation, diffusion, and circulation

 ↓ elastic recoil in alveoli

↓ alveolar-capillary interface

low lung vol/↓ vent --> distal airway collapse

Difficulty w/ expiration = primary problem

↓ # of cilia, remaining are less effective/strong

↓ mucus elevator and alveolar macrophage activity - less able to move inhaled particles

prolonged due to:

↑ relative work rate

↑ proportion anaerobic metabolism

slower heat elimination

↓ physical fitness level

NOT NORMAL - ↓ enamel area for mastication, ↓ intermaxillary space

↓ motility

↓ relaxation of lower sphincter *presbyesophagus = substernal sense of fullness

↓ lower resting pressure - reflux

↓ motility --> delayed gastric emptying time

↓ GI digestion, can affect med absorption

↓ blood supply, ↓ # of absorbing cells --> constipation

↑ incidence gallstones due to ↓ cholesterol stabilization

↓ mass and blood perfusion

↓ metabolism of drgs --> alterations in protein binding and prolonged drug effects

↓ enzyme volume and concentration affects digestion

↓ insulin use

↓ ability of Beta cells to increase insulin production in response to increased blood glucose

↓ functioning nephrons (30-40% of was available)

↓ renal perfusion - Bowman's capsule membrane thick, ↓ renal tubule functioning, ↓ urinary concentration

↑ uninhibited contractions, residual urine, reflux --> UTI

↓ brain weight and gyral thickness w/ increased ventricular size - cerebellum and cerebral cortex most affected

Amyloid plaques and neurofibrillary tangles

decline in serotonin, catecholamines, GABA

↓ nerve conduction velocity due to loss of myelin sheath and axons

axonal loss --> fewer mm fibers and loss of fine sensation

loss of sensory neurons - especially pain & temp

ANS dysfunction

slowed response time

↓ touch, temp, pain, vibration

↓ growth rate, healing response, thermoregulation, sensory perceptions

Wrinkles and pigmented lentigos (age spots) w/ sun exposure

thinner dermis, ↓ elasticity, ↓ vascularity

capillaries easily damaged

↓ # and size of sweat glands

↓ sweat production

slow nail growth

↓ # Pacinian & Meissner's corpuscles, 1/3 of original by 90

light touch threshold increased especially hands/feet

↓ vibration sensitivity especially after 80

↓ proprioceptive sensitivity starting after 20s, LE 2x > after 50s

Proximal > distal sensitivity

Age related SENSORINEURAL decline in hearing

loss of sensory cells (organ of Corti)

degeneration of hair cells

atrophy of vasculature/connective tissue

loss of neurons in central auditory centers

↓ high frequency

processing and discrimination

75% 70+

cochlear implants (aids only magnify distorted sounds)

dizziness & vertigo

20-40% reduction of hair cells in saccule, utricle, and semi-circular canals

by 75, # myelinated vestibular nerve fibers ↓ by 40%

Prebystasis = age related decline in equilibrium/dynamic balance when no other pathology noted

80% loss in acuity at 85, most rapid decline 60-80

cornea & lens thickening, ↓ lens curvature, yellowish pigment

↓ peripheral & upper visual fields

Senile Miosis = ↓ pupillary size --> increased light sensitivity

delayed dark adaptation

Presbyopia - far sighted

color perception, contrast and depth perception

loss smell > taste

3/4 olfactory bulb fibers lost by 80

↓ taste bud function 2' loss

sweet and salty go first

↓ saliva

use of dentures

gum disease