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Physiological and Clinical Changes of Aging
Pio L. Oliverio, MD
Fellow, Geriatrics
SVCMC, Jamaica, NY
OBJECTIVES
1. To describe basic concepts of physiologic changes with aging
2. To describe the effect of aging on body processes/ systems
DEFINITION of TERMS
Aging – the process of growing old, specially by failure of replacement cells in sufficient number to maintain full functional capacity
(Stedman’s Med Dictionary 2000)
DEFINITION of TERMS
Aging – the gradual deterioration of a mature organism resulting from time-dependent, irreversible changes in structure that are intrinsic to the particular species, and that eventually lead to decreased ability to cope with the stresses of the environment thereby increasing the probability of death
(Stedman’s Med Dictionary 2000)
DEFINITION of TERMS
Aging – is a process that converts healthy adults into frail ones with diminished reserves in most physiologic systems and exponentially increasing vulnerability to most diseases and to death
(W. Hazzard, Principles of Geriatric Medicine & Gerontology 2003)
DEFINITION of TERMS
Gerontology – the scientific study of the process and problems of aging.
Geriatrics – the branch of medicine concerned with the medical problems and care of the aged
DEFINITIONS of Life Span A lifetime The average or maximum length of time an
organism or object can be expected to survive or last
The maximum number of years that a person has been known to live, currently around 115 years
Frequently confused with life expectancy
DEFINITION of Life Expectancy length of time that a person on the average is
expected to live average number of years of life remaining to a
person at a particular age and is based on a given set of age-specific death rates
Also Average Life Span or Mean Life Span Can change over life cycle Based on statistical probabilities
Average Life Expectancy
61 – developing countries
74 – developed countries
(In years)
VARIATIONS
WORLD WIDECauses: differences in public health
medicine and nutrition from country to country
USA + other developed countriesVariation in ethnicity and gender
in life expectancy
FACTORS
Genetic disorder
Exercise Smoking Excessive
drug and alcohol use
affecting life expectancy
Poverty Air pollution Occupation Diet Access to
health care
Fundamental Considerations
1. Aging is developmental
2. Old age is a gift of 20th century technology and scientific advancement
3. The effects of normal aging vs. pathologic aging must be differentiated
4. There is no universally accepted theory of aging
Theories of Aging
Oxidative stress (free radical) Theory• Tissue damage is caused by free radicals
(super oxide or hydroxyl radicals) through lipid peroxidation
• Specific form of wear and tear theory
• Accumulation of aging pigments (lipofuscin) in lysosomes
Theories of Aging
Rate of Living Theory (Metabolic Rate Theory)
•The higher the basal metabolic rate (the rate, at which the body at rest, uses energy), the shorter the life span
Theories of Aging
Error Catastrophe Theory• DNA errors promote senescence,
programmed cell death (apoptosis)
• Aging results from gene interference with the ability of the cells to reproduce
Theories of Aging
Error Catastrophe TheoryRedundant DNA Theory
• Biologic age changes are a result of errors accumulating in functioning genes
• Lifespan may be a degree of repeated genetic sequences
• Fails to explain other possible aging factors
Theories of Aging
Hayflick Limit Theory• Functional changes within cells are
responsible for aging
• Cumulative effect of improper functioning of cells and eventual loss of cells in organs and tissues
Cardiovascular System
Morphology:
1. Elongation and tortuosity, stiffening of arteries including aorta
2. Increase intimal thickening of arteries
3. Increased fibrosis of media of arteries
4. Sclerosis of heart valves
Cardiovascular System
Cardiac Hypertrophy with aging Inotropic and chronotropic responses to
catecholamines sympathetic nervous system are impaired
Both systolic and diastolic blood pressures increase with age
Blood pressure regulation: older patients are at high risk for orthostatic hypotension
Cardiovascular System
Decreased •Cardiac output
•Heart rate response to stress
•Compliance of peripheral blood vessels
Respiratory System
Decreased
• Lung elasticity
• Activity of cilia
• Cough reflex
• Respiratory drive
Respiratory System
Lower…• Respiratory muscle
strength & endurance
• Diffusing capacity (oxygen uptake)
• PO2, O2 saturation due to V/Q mismatch (but no change in PcO2 )
Respiratory System
Lower• Maximal expiratory flows:
FEV1, FEV1/FVC
• VC
Increased•FRC and RV
Stable•TLC
Renal System
Decreased • Number of nephrons
• Kidney weight and volume
• Lean body mass
• Maximum urine osmolality
Renal System
Decreased •Renal blood flow
• Creatinine clearance
•Renin response to volume depletion or salt restriction
Renal System
Impaired: Hydroxylation of Vitamin D Metabolism of PTH, calcitonin and
glucagon
Unchanged: Erythropoietin production
Musculoskeletal System
Most common disability cause in > 65 years old
Decrease in:• Muscle mass
• strength of grip/ contractile force
• stability of neuromuscular innervation
• Bone substance (osteoporosis)
• Height and Weight
Gastrointestinal System
Decreased:• Hydrochloric acid production
• Taste buds
• Intestinal motility
• Swallowing coordination
• Vitamin K-Dependent factor synthesis
Gastrointestinal System
Increased:• Lithogenic index of bile composition
(cholesterol gallstones)
Functional Changes (Large Intestine):• Slowed transit
• Altered coordination of contraction
• Increased opioid receptors (drug induced constipation)
Endocrine System
Decreased:• Free testosterone
• Triiodothyronine
• Cortisol production
• Hypothalamic-pituitary-adrenal axis sensitivity to glucocorticoid feedback
Endocrine System
Increased:
•Insulin
•Norepinephrine
•Parathoromone
•Vasopressin
Immune System
Impaired thermal regulation•Afebrile infection common
Total lymphocyte counts do not change with age
TNF-alpha increased but not interleukin-1
Immune System
Decreased:Humoral antibody-mediated responseAntibody response to vaccinesProduction of thymic hormonesMass of thymus
• Production of lymphocytesT-cell activity
Vision
Retina becomes thinnerChanges in lens and iris =
presbyopiaCataract formation:
• Lens yellows and accumulation of insoluble protein in center…
Vision
• Lacrimal gland function
• Tear production
• Goblet cell function
• Acuity
• Accomodation
• Color sensitivity
• Depth perception
• Pupil size
• Aqueous humor production
Decreased:
Hearing
External auditory canal atrophies Cerumen becomes drier
Hearing Loss caused by: Loss of hair cells in the organ of Corti Loss of cochlear neurons Stiffening of the basilar membrane Calcification of auditory mechanism Degeneration of spiral ligament
Thermoregulation
Increased susceptibility to hypo/hyperthermia
Impaired vasoconstrictor response to cooling
Impaired ability to conserve heat Impaired skin vasodilatation response Decreased sweat production
Sexual Function
Slower arousal phaseIncreased ability to stay at plateau
levels of arousalEstrogen loss reduces acidity of
vaginal secretions, causes atrophic vaginitis and hot flashes
Sexual Function
In men, a longer refractory periodIn older men, erectile dysfunction
impotence. There is no such thing as male menopause
THANK YOU!for your attention
and your time