From: "Stress." Britannica Student
Encyclopedia 2003 Encyclopdia Britannica Online.
24 Feb, 2003 :
The body's response to a threat or demand
arising from a new or changing situation is called
stress. The emotional and physical
experiences of stress can be caused by a complex
and tense situation. Under stress, the body makes
rapid physiological changes, called adaptive
responses, to deal with threatening
situations. In the first stage of stress,
alarm, the body mobilizes its fight or flight
defenses, either to resist the stress-causing
factor or adapt to it. In this stage, the
pituitary-adrenocortical system pours hormones
into the bloodstream. The pulse quickens, the
lungs take in more oxygen to fuel the muscles,
blood sugar increases to supply added energy,
digestion slows, and perspiration increases.
In the second stage of stress,
resistance, the body begins to repair the
incidental damage caused by the arousal in the
alarm stage. If the stressful situation is
resolved, the stress symptoms vanish. If the
stressful situation continues, however, a third
stage, exhaustion, sets in, and the body's
adaptive energy runs out. This stage may
continue until vital organs are affected, and then
disease or even death can result.
Medical scientists divide people's behavior
into two types, depending on the individuals'
reactions to stress. People with type-A
behavior react to stress with aggressiveness,
competitiveness, and self-imposed pressure to get
things done. Type-A behavior has been linked to
increased rates of heart attack and other
diseases. In the United States two of every three
men and one of every two women demonstrate type-A
characteristics. People with type-B behavior
may be equally serious in their intentions, but
are more patient, easygoing, and relaxed.
Life events may have a strong effect on an
individual's susceptibility to disease. The
Holmes-Rahe Social Readjustment Rating Scale
ranks a number of life events in order of their
estimated level of stress. Death of a spouse has a
rating of 100 stress points, making it the most
stressful event on the list, while minor
violations of the law have a rating of only 11
points. Stress is a major factor in diseases that
have a significant psychosomatic component, that
is, diseases whose physical symptoms are induced
or aggravated by mental or emotional disturbances.
Stress-related disorders compose 50 to 80 percent
of all illnesses, though stress may not be the
only cause. Such disorders include high blood
pressure, cardiovascular disease, arthritis and
other inflammatory diseases, asthma, insomnia and
other sleep disturbances, and anorexia nervosa and
other eating disorders. Stress is also related to
migraine headaches, ulcers, respiratory or lung
diseases, and skin disturbances. Although a link
between stress and cancer is uncertain, some
experts believe there is a type-C
personalityone who is cancer prone because of
Stress experts frequently emphasize that stress
can be good as well as bad and advise their
patients to make it work for them as a source of
energy. They suggest the following ways to manage
(1) Have a code of life and live positively.
(2) Set priorities to avoid unnecessary time
(3) Allow time for pleasurable activities such as
taking walks or talking with friends.
(4) Exercise regularly as an outlet for stress.
(5) Eat a sensible diet to maintain the energy
needed to cope with stress.
(6) Learn self-relaxation techniques such as deep
breathing, muscle relaxation, and meditation.
Definition of stress in biological terms:
Stress can be any condition which causes the
release of certain hormones, called
glucocorticoids, into the blood stream.
These hormones are released by a mass of tissue,
called the adrenal gland, which lies on top of
Hormones are chemicals which are released by
certain cells of the body, travel through the
blood, and tell other cells in the body what to
do; they are a kind of messenger.
Glucocorticoids are messengers which tell
the body that it is in a stressful situation.
They tell the heart to beat faster, they tell the
muscles to get ready to respond if needed, and
they tell the stomach to stop digesting food.
Basically, they get the body ready to fight or run
away from a stress.
You know that many functions of the body, for
example heartbeat and digestion, are not under
voluntary control, which also means that they
continue during sleep. These functions are
controlled by the autonomic nervous system,
which has two subsystems, the sympathetic and
the parasympathetic nervous systems.
The sympathetic nervous system reacts when
the organism is threatened. This system is
therefore responsible for all the physiological
reactions of your body to a stress factor. For
example, it increases heartbeat and breathing
rate, digestion stops and the pupils dilate.
The parasympathetic nerve fibers connect to
the same organs as the sympathetic nerve fibers,
but they cause just the opposite effects. After
the stress is over, the parasympathetic system
tells the body to go back to normal , the stress
is over. The heart decreases, the stomach relaxes,
digestion starts again, breathing slows down, and
the pupils of the eyes contract. Thus, the
parasympathetic division rests the body after
stress and accumulates energy for the next
emergency. The sympathetic reaction to stress
has evolved to help animals in situations of
danger, in which they are face with the choice of
"fight or flight". Humans have evolved beyond the
necessity to defend our lives on a daily basis,
but exams, dentist appointments, first dates and
other stressors of the modern world all call upon
our sympathetic nervous system! We humans
experience less acute stress and more chronic
stress (the type cause by a demanding job or a
difficult relationship) than ever. This chronic
stress keeps our body in a constant out of
equilibrium state and imposes great strains on our
various systems. Chronic stress is known to cause
problems of the heart, liver; lungs and kidneys
and to be linked to a variety of diseases, most
notably cancer. Chronic stress also causes
depression and leads to self-destructing behaviors
such as smoking, alcoholism, drug abuse and suicide,
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