CHANGES WITH AGING - IMMUNE SYSTEM
The Immune System
The immune system becomes slightly less effective with
aging. This is so slight
that it is only noticed when infections linger or become
severe. People who are infected with tuberculosis during
early adulthood may have no symptoms until old age.
Then, symptoms develop because the immune system is
weaker.
The immune system may be less able to distinguish the
body's own cells from foreign substances that invade
the body.
Consequently, autoimmune disorders in which the immune
system attacks some of the body's own cells become more
common.
The cells of the immune system destroy cancer
cells, bacteria, and other foreign substances more slowly.
This slowdown may be one reason that cancer is more
common among older people. Also, vaccines tend to be
less protective in older people. These changes in the
immune system may help explain why some infections,
such as pneumonia and influenza, are more common among
older people and result in death more often.
The various age-related changes that influence our
bodies' ability to resist and control infections include:
- Barrier Defences
- Physical And Mechanical Defences
The Barrier Defences
The skin and mucous
membranes that line body cavities are primary barriers
to infection by trapping organisms in secreted mucus
and removing them by ciliary transport toward a body
opening such as the mouth. Aging may compromise this
barrier function, which commonly occurs in the mouth,
urethra, and vagina.
Some of the barrier and antimicrobial properties of
the skin may be impaired with age. In addition, certain
skin conditions that predispose one to infection, including
pressure ulcers wounds, lesions and bruises, become
common.
Physical and Mechanical Defences
Difficulties in swallowing is a common
and age-related change. This predisposes individuals
to aspiration, drawing substances into the lungs instead
of swallowing them through the oesophagus. This results
in pneumonia, a common condition in older people.
Our cough mechanism decreases as
we age, further reducing our ability to eliminate organisms.
Changes in the lung, especially the collapse of small
airways and the overall loss of lung elasticity, also
increase the risks of infection.
In the gastrointestinal system, the stomach
secretes reduced amounts of acid. The bowel's
contractions can change, and out-pouchings called diverticula
often form in the bowel lining. All of these changes
make it easier for bacterial populations to increase
in the gastrointestinal system.
Changes in the urinary tract lower resistance to infection
due to:
- Changes in the chemistry of the urine
- Reduced prostatic fluid and a further reduction
in its ability to kill organisms
- Diminished flushing mechanism of the bladder and
backward flow of bladder contents toward the kidney
- Obstruction of urine flow by prostate enlargement,
bladder prolapse, narrowing of the urethra, or kidney
stones.
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Impaired Response
The white blood cells do not appear to change as we
age, nor does their ability to attack organisms seem
to be impaired. Whilst they continue to respond normally
to signals to combat infecting organisms, should one
develop fever with infections, reduced or absent fever
responses are not rare.
An impaired response to a stimulus with age appears
to be due to reduced numbers and diminished responsiveness
of certain lymphocytes and other cell lines.
This decline in immune responsiveness may be responsible
for our increased tendency to infections, cancer, and
various immune diseases as we age.
On the positive side, due to our body's impaired production
of antibodies in old age, allergy symptoms may become
less severe.
How
To Build Your Immune System
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