PHYSIOLOGY OF AGING
“Age is an issue of mind
over matter.
If you don't mind, it
doesn't matter."
Mark Twain
(1835-1910)
SO
“You're Only As Old As
You Feel”
AGING PROCESS
• Normal Part of Life.
• Begins around ……..
age 30.
“If I'd known I was gonna live this
long, I'd have taken better care of
myself.”
Eubie Blake (1883-1983)
American Jazz Musician
Changes in Physiology with
Aging
• Older people may exhibit no changes in
baseline function, but may have
decreased ability to adapt to stress.
• Various body systems lose reserve
capacity with aging at different rates.
“I am sick of all this nonsense about
beauty being only skin deep.
That’s deep enough. What do you
want, an adorable pancreas?”
Jean Kerr
Factors affecting aging of facial features
Smoking
Exposure to sun
Use of alcohol
BMI
BMI = kg/m²
<18.5 = Underweight
18.5-24.9 = Normal
25-29.9 = Overweight
30 or more = Obesity
“O” Complex of Geriatric Medicine
Changes in Physiology with
Aging
• Decreased Homeostasis.
• Older people may exhibit no changes in
baseline function, but may have
decreased ability to adapt to stress.
• Various body systems lose reserve
capacity with aging at different rates.
Changes in Vision and Hearing
Significant visual & hearing impairment is
present in up to 75% of elderly people
– Often not reported to the physician
– May limit ability to function
– May lead to social isolation
– May interfere with ability to communicate
– May appear demented
For older people this means:
• Sensory Deprivation
• Increased risk for falls
• Decreased quality of life
Vision
Eyes
– Loss of fat – sunken appearance; eye bags
– Presbyopia
– Slower adaptation to darkness
– Diminished tolerance to glare
– Increasing impairment to colour discrimination
– Increased lens density
– Macular degeneration
– Degeneration of tear gland
SYMPTOMS
• Cannot get glasses clean
• Difficulty night driving
• Difficulties reading
• Double vision (in one eye)
Normal Lens
Cataract
What is your vision like with
cataract?
Monet’s painting - Before
Monet’s painting - With
‫זווית פתוחה ‪Glaucoma‬‬
Age-Related Macular Degeneration
Risk factors for AMD
•
•
•
•
•
•
Increased age
Female gender
Lighter iris color
Race
Smoking
Sunlight Exposure
Diabetic Neuropathy
Hearing Loss
Ears
– Loss of elasticity in inner ear leading to
loss of high frequency hearing.
– Sounds from speech is distorted due to
poor quality amplification
Changes in Auditory and Visual
Function with Age
• Sensorineural hearing loss – presbycusis.
• Conductive hearing loss may also occur.
• The lens decreases its elasticity and becomes less
mobile.
• Cataracts may develop.
• Loss of fat in the eyelids and reduced tone of the
levator muscle causes drooping (ptosis) of the
eyelid.
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Overview of Hearing Loss
• 60% of elderly over 65 have some
degree of hearing impairment.
• 90% of people over 75 have some
degree of hearing impairment!
• 75% of all people with hearing loss
could benefit from an appropriate
hearing aid.
Signs of Hearing Loss
•
•
•
•
•
•
•
•
•
Ringing or buzzing in the ears
Talking louder than necessary
Turning up volume on the TV or radio
Complaints that other people “mumble”
Confusion of similar sounding words
Watching a speaker’s face intently
Difficulty “hearing” someone behind you
Having difficulty on the telephone
Inappropriate responses in conversation
Changes in Vision and Hearing
• Significant visual, hearing impairment is
present in up to 75% of elderly people
– These problems are often not reported to the
physician
– May limit ability to function
– May lead to social isolation
– May interfere with ability to communicate
– patients with sensory impairments may
appear demented
For older people this means:
• Sensory Deprivation
• Increased risk for falls
• Decreased quality of life
Changes in Heart
The Cardiac Cycle
Cardiac Cycle
Cardiac Output (CO) = Stroke Volume (SV) x Heart Rate (HR)
Changes in Cardiovascular
Physiology
•
Changes in cardiac output (CO):
– Maximal heart rate decreased with aging (max. heart rate = 220 - age)
– Increased end-diastolic and end-systolic left ventricular volumes
•
Diastolic dysfunction
– Decreased early diastolic filling
– Increased reliance on atrial contraction
– Increased vulnerability to congestive heart failure, especially with atrial fibrillation
•
Decreased compliance of peripheral blood vessels
– predisposes to systolic hypertension, left ventricular hypertrophy of heart
•
Increased incidence of atherosclerotic cardiovascular disease
•
Increased incidence of degeneration of cardiac conduction system
Cardiovascular System
• The resting cardiac output can remain
stable with conditioning exercise in the
absence of disease however the output
with exercise will be reduced even in
healthy aging.
Disease Presentation
• Atypical symptomatology
- Chest pain less frequent
- Exertional dyspnea or fatigue more common
- ‘Gastrointestinal’ symptoms more common
- Confusion, dizziness, other CNS symptoms
• Non-diagnostic ECG due to co-founding
factors
• Most MIs are Non ST Elevation MI
For older people this means:
• Decrease in capacity to cope with the
demands of physical activity.
• Simple daily tasks become less
achievable.
Changes in Pulmonary
Physiology
Changes in Pulmonary
Physiology
• Decreased elasticity
– Decreased vital capacity
– Increased residual volume
• Decreased structural support for small
airways
– Decreased number of small airways open
during normal breathing
For older people this means:
• Poor effort tolerance
• Greater susceptibility to infections
• Pneumonia
• TB
• Viral Infections
• Difficulty to differentiate between ageing
process and environmental damage
Respiratory System
• Reduced
- Lung surface area
- Alveolar elasticity
- Forced Expiratory Volume (FEV 1)
- Maximal Oxygen Consumption (VO2 max)
- P O2
• Increased
- Chest wall stiffness
Osteoporosis and kyphosis can reduce the
thoracic capacity. That and alveolar stiffness
leads to “senile emphysema” with an
FEV1/FVC < 70% of the predicted for age and
gender
Respiratory function
• Alveolar function unchanged with age
• Noticable change is reduction in lung compliance
• Also loss of elasticity and reduction in strength of muscles
of rib cage reduces usable lung capacity to 82% maximum
value by age 45; 62% at age 65; and 50% at age 85
• Over time some alveoli replaced by fibrous tissue
• Gas exchange reduced
• Main problems arise with increased demand (exercise)
50
SMOKING
Never
smoked
Stopped
at 45y
Smoker
Stopped
at 65y
Renal System
– Loss of diurnal excretory pattern increasing
nocturia
– Loss of nephrons
– Reduced plasma blood flow and GFR
– Serum Creatinine will not reflect the GFR as the
muscle mass is reduced.
Changes in
Renal/Fluid/Electrolytes
• Decreased glomerular filtration rate, renal blood
flow, creatinine clearance.
•
Decreased adaptive mechanisms:
– Decreased salt conservation
– Increased risk of volume depletion
– Increased risk volume overload with saline
• Decreased free water conservation
– Decreased maximal urine concentration
• Decreased sense of thirst
Aging and RBF
ml/min
600
300
20
50
Age
80
Note: Arterial collagen deposition increases with age; there is gradual cortical glomerular scarring
Aging and GFR
ml/min
150
75
20
50
Age
80
Note: Glomerular filtration pressure autoregulation is less effective in the elderly
Changes in Fluid & Electrolytes
• Relative excess of antidiuretic hormone
(ADH)
• Alterations in renal potassium handling
For older people this means:
• Possible Water intoxication
• Hyperkalemia
• Increased risk for dehydration
• Increased drug toxicity
Renal function
• Vessels supplying nephrons can become
atherosclerotic
• Fall in GFR may occur
• Affect kidneys ability to excrete metabolites and drugs
• At age 80, reduced to 50%
• Consequences on homeostasis (eg)
• Main problem is reduced ability to respond to salt load
or depletion
• Acid base balance
• Urinary incontinence
59
Musculoskeletal Changes
• Decrease in muscle weight relative to
total body weight
• Changes in water content of cartilage
• Bone loss in both sexes but more
pronounced in women
For older people this means:
• Chronic pain
• Decrease in functional ability
contributing to morbidity
• Lack of independence leading to
decreases in quality of life
Neuromuscular
• Reduced propioceptive information
• Delayed nerve conduction
• Reduced numbers of motor neurons
• Reduced fast twitch fibers
• Reduced muscle mass
For older people this means:




Plan simple movement tasks
Longer transition times
Lots of verbal and visual cues
Functional moves.
Changes in Strength with Aging
• Opening the cap on a jar:
– Completed by 92% of men and women
between 40 – 60 years of age
– Completed by 32% of men and women
between 71-80 years of age
The Digestive System
Motility
Secretion
Absorption
Age Related Changes of Taste
• General decrease in taste due to
decreased central sensation.
• Decreased salivary volume.
• Formation of fissures and furrows on the
tongue.
Gastrointestinal System:
• Smooth muscle contraction diminished.
• Deterioration of structures in mouth common.
• Decline in efficiency of liver.
– Reduced ability to aid in digestion and metabolism of certain
drugs
• Impaired swallowing.
– Stomach sphincter valve loss.
• Decrease in nutrient absorption.
For older people this means:
• Constipation is common.
• Poor fitting dentures.
• Increase in heartburn.
• Malnutrition due to deterioration of small
intestine.
Standard eating environment
Improved eating environment
“The secret of staying young is to live
honestly, eat slowly, and…….
lie about your age.”
Lucille Ball