PHYSICAL AGING PROCESS WHEN DOES OLD AGE BEGIN?

DEFINITION OF AGING Old and aging depends on the age and experience of the speaker. Chronological age - number of years lived Physiologic age - age by body function Functional age - ability to contribute to society

CHRONOLOGICAL CATEGORIES Young-Old - (ages 65 - 74) Middle-Old - (ages 75 - 84) Old-Old - (age 85 and older)

FRAIL ELDERLY Characteristics: Poor mental and physical health Low socioeconomic status Predominantly female Possibly isolated living conditions More and longer hospital stays, and More money spent on health care and drugs

PHYSICAL THEORIES OF AGING What causes the body to age?

PROGRAM THEORY Cells replicate a specific number of times and then die. Happens again, and again in lab experiments.

ERROR THEORY The structure of DNA is altered as people age Due to alterations, DNA not read correctly Results in transcription and translation malfunction Results in aging/illness/ cancer directly, or indirectly

Normal wear and tear causes cells to function improperly CELLULAR THEORY Normal wear and tear causes cells to function improperly

FREE RADICAL THEORY Lipids in cell membranes are exposed to radiation or free radicals Cell membrane ruptures and cell dies In test tubes this actually occurs

NUTRITIONAL MODEL THEORY If animal fed 50-60% less than it eats on its own - lives longer Assumption: Lean mass, as opposed to adipose tissue results in greater health

COLLAGEN THEORY OF AGING As we age, collagen in body ages also. Causes hypertension and other organ malfunctions

MUTATING AUTO-IMMUNE THEORY Cells have normal functions - secrete normal proteins As cells age - mutate and secretions viewed as foreign by body Solicits immune response Shuts cell down Cause biological errors and entire organ malfunctions

NEURO-AGING THEORY All cells undergo nervous system degeneration Results in changes in hormonal release Leads to decline in cell function

NONE OF THESE THEORIES TOTALLY ACCEPTED Scientists hypothesize it might be combination of several or all

PHYSIOLOGICAL AGING OF THE HUMAN BODY BY SYSTEMS

SKIN, HAIR, NAILS Loss of subcutaneous fat Thinning of skin Decreased collagen Nails brittle and flake Mucous membranes drier Less sweat glands Temperature regulation difficult Hair pigment decreases Hair thins

EYES AND VISION Eyelids baggy and wrinkled Eyes deeper in sockets Conjunctiva thinner and yellow Quantity of tears decreases Iris fades Pupils smaller, let in less light Night and depth vision less “Floaters” can appear Lens enlarges

EYES AND VISION CONT. Lens becomes less transparent Can actually become clouded Results in cataracts

EYES AND VISION CONT. Accommodation decreases Results in presbyopia Impaired color vision, also - especially greens and blues Because cones degenerate

EYES AND VISION CONT. Predisposed to glaucoma Increased pressure in eye Decreased absorption of intraocular fluid Can result in blindness

EYES AND VISION CONT. Macular degeneration becoming more frequent This is the patch of retina where lens focuses light Ultimately results in blindness Reason for current increase in this condition unknown

EARS AND HEARING LOSS Irreversible, sensorineural loss with age Men more affected than women Called presbycusis Loss occurs in higher range of sound By 60 years, most adults have trouble hearing above 4000Hz Normal speech 500-2000Hz

RESPIRATORY SYSTEM Lungs become more rigid Pulmonary function decreases Number and size of alveoli decreases Vital capacity declines Reduction in respiratory fluid Bony changes in chest cavity

CARDIOVASCULAR SYSTEM Heart smaller and less elastic with age By age 70 cardiac output reduced 70% Heart valves become sclerotic Heart muscle more irritable More arrhythmias Arteries more rigid Veins dilate

GASTROINTESTINAL SYSTEM Reduced GI secretions Reduced GI motility Decreased weight of liver Reduced regenerative capacity of liver Liver metabolizes less efficiently

RENAL SYSTEM After 40 renal function decreases By 90 lose 50% of function Filtration and reabsorption reduced Size and number of nephrons decrease Bladder muscles weaken Less able to clear drugs from system Smaller kidneys and bladder

REPRODUCTIVE SYSTEM Male: Reduced testosterone level Testes atrophy and soften Decrease in sperm production Seminal fluid decreases and more viscous Erections take more time Refractory period after ejaculation may lengthen to days

REPRODUCTIVE SYSTEM Female: Declining estrogen and progesterone levels Ovulation ceases Introitus constricts and loses elasticity Vagina atrophies - shorter and drier Uterus shrinks Breasts pendulous and lose elasticity

NEUROLOGICAL SYSTEM Neurons of central and peripheral nervous system degenerate Nerve transmission slows Hypothalamus less effective in regulating body temperature Reduced REM sleep, decreased deep sleep After 50% lose 1% of neurons each year

MUSCULOSCELETAL SYSTEM Adipose tissue increases with age Lean body mass decreases Bone mineral content diminished Decrease in height from narrow vertebral spaces Less resilient connective tissue Synovial fluid more viscous May have exaggerated curvature of spine

IMMUNE SYSTEM Decline in immune function Trouble differentiating between self and non-self - more auto-immune problems Decreases antibody response Fatty marrow replaced red marrow Vitamin B12 absorption might decrease - decreased hemoglobin and hematocrit

ENDOCRINE SYSTEM Decreased ability to tolerate stress - best seen in glucose metabolism Estrogen levels decrease in women Other hormonal decreases include testosterone, aldosterone, cortisol, progesterone