physical aging process when does old age begin?. definition of aging old and aging depends on the...
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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
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