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