Physical Aging Process

• Physical aging process is about when old age begins.

Definition of Aging

• How old age is perceived is dependent on the age and experience of the speaker.
• Chronological age is the number of years lived.
• Physiological age is defined by age by body function.
• Functional age is defined by the ability to contribute to society.

Chronological Categories

• Young-old is categorized as ages 65-74.
• Middle-old is categorized as ages 75-84.
• Old-old is categorized as age 85 and older.

Frail Elderly

• Frail elderly tend to have poor mental and physical health.
• Frail elderly's socioeconomic status is low.
• Frail elderly are predominantly female.
• Frail elderly possibly live in isolated conditions.
• Frail elderly tend to have more and longer hospital stays.
• Frail elderly spend more money on healthcare and drugs.

Physical Theories of Aging

• The physical theories of aging are about what causes the body to age.

Program Theory

• Cells replicate a specific number of times and then die, repeatedly in lab experiments.

Error Theory

• The structure of DNA is altered as people age, therefore DNA is not read correctly.
• This results in transcription and translation malfunction.
• This results in aging, illness, and cancer, directly or indirectly.

Cellular Theory

• Normal wear and tear causes cells to function improperly.

Free Radical Theory

• Lipids in cell membranes get exposed to radiation or free radicals.
• Cell membranes rupture and cells die.
• This has been shown to occur in test tubes.

Nutritional Model Theory

• Animals fed only 50-60% of what they eat live longer.
• Lean mass as opposed to adipose tissue results in greater health.

Collagen Theory of Aging

• Collagen ages as the body ages.
• This causes hypertension and other organ malfunctions.

Mutating Auto-Immune Theory

• Cells have normal functions that secrete normal proteins.
• As cells age, they mutate, and these secretions are viewed as foreign by the body.
• This triggers an immune response, and the cell shuts down.
• This causes biological errors and entire organ malfunctions.

Neuro-Aging Theory

• All cells undergo nervous system degeneration.
• This results in changes in hormonal release.
• This leads to decline in cell function.
• None of these theories are totally accepted, but scientists hypothesize that aging is a combination of several or all of them.

Physiological Aging by Systems

• Physiological aging of the human body varies by system.

Skin, Hair, Nails

• There is a loss of subcutaneous fat.
• The skin thins and collagen decreases.
• Nails become brittle and flake.
• Mucous membranes become drier.
• There are less sweat glands.
• Temperature regulation is more difficult.
• Hair pigment decreases and hair thins.

Eyes and Vision

• Eyelids become baggy and wrinkled.
• Eyes are deeper in sockets.
• The conjunctiva thins and yellows.
• The quantity of tears decreases.
• The iris fades.
• Pupils get smaller, letting in less light.
• Night and depth vision decreases.
• "Floaters" can appear.
• The lens enlarges.
• The lens becomes less transparent and clouded, resulting in cataracts.
• Accommodation decreases, resulting in presbyopia.
• Color vision is impaired, especially greens and blues.
• This is a result of cones degenerating.
• There is a predisposition to glaucoma.
• This is a result of increased pressure in the eye.
• This is a result of decreased absorption of intraocular fluid.
• This can result in blindness.
• Macular degeneration becomes more frequent.
• The retina is the patch where the lens focuses light.
• This ultimately results in blindness.
• The reason for the current increase in this condition is unknown.

Ears and Hearing Loss

• Hearing loss in old age is irreversible and sensorineural.
• Men are more affected than women.
• It is called presbycusis
• Loss occurs in higher range of sound.
• By age 60, most adults have trouble hearing above 4000 Hz.
• Normal speech is 500-2000 Hz.

Respiratory System

• Lungs become more rigid.
• Pulmonary function decreases.
• The number and size of alveoli decreases.
• Vital capacity declines.
• Reduction in respiratory fluid.
• Bony changes occur in the chest cavity.

Cardiovascular System

• The heart becomes smaller and less elastic with age.
• By age 70, cardiac output is reduced 70%.
• Heart valves become sclerotic.
• Heart muscle becomes more irritable.
• More arrhythmias occur.
• Arteries become more rigid.
• Veins dilate.

Gastrointestinal System

• GI secretions and motility are reduced.
• The liver decreases in weight.
• The regenerative capacity of the liver decreases.
• The liver metabolizes less efficiently.

Renal System

• After age 40, renal function decreases.
• By age 90, 50% of function is lost.
• Filtration and reabsorption are reduced.
• The size and number of nephrons decrease.
• Bladder muscles weaken.
• There is less ability to clear drugs from the system.
• Kidneys and the bladder become smaller.

Reproductive System (Male)

• Testosterone levels are reduced.
• Testes atrophy and soften.
• Sperm production decreases.
• Seminal fluid decreases and becomes more viscous.
• Erections take more time.
• The refractory period after ejaculation may lengthen to days.

Reproductive System (Female)

• Estrogen and progesterone levels decline.
• Ovulation ceases.
• The introitus constricts and loses elasticity.
• The vagina atrophies, becoming shorter and drier.
• The uterus shrinks.
• Breasts become pendulous and lose elasticity.

Neurological System

• Neurons of the central and peripheral nervous system degenerate.
• Nerve transmission slows.
• The hypothalamus is less effective in regulating body temperature.
• Reduced REM sleep occurs with decreased deep sleep.
• After age 50, 1% of neurons are lost each year.

Musculoskeletal System

• Adipose tissue increases with age.
• Lean body mass decreases.
• Bone mineral content diminishes.
• A decrease in height occurs from narrow vertebral spaces.
• Less resilient connective tissue.
• Synovial fluid is more viscous.
• There may be an exaggerated curvature of the spine.

Immune System

• Immune function declines.
• Trouble differentiating between self and non-self results in more auto-immune problems.
• Antibody response decreases.
• Fatty marrow is replaced with red marrow.
• Vitamin B12 absorption might decrease, decreasing hemoglobin and hematocrit.

Endocrine System

• Decreased ability to tolerate stress is best seen in glucose metabolism.
• Estrogen levels decrease in women.
• Other hormonal decreases include testosterone, aldosterone, cortisol, and progesterone.