The common abbreviation for adreno-
corticotrophin). ACTH is produced by
the anterior part of the
the base of the brain) and stimulates the
situated on the top of
the kidneys) to release various
ACTH is also necessary
for the growth and maintenance of the
cells of the adrenal cortex.
The most important function of ACTH
is to stimulate the adrenal cortex to
increase its production of
(cortisol). ACTH also causes the adrenal
cortex to release
The production of ACTH is controlled
by a feedback mechanism that involves
(an area in the
centre of the brain) and the level of
ACTH levels are high, the production of
hydrocortisone increases, which in turn
suppresses the release of ACTH from the
pituitary gland. If ACTH levels are low,
hydrocortisone production falls and the
hypothalamus releases factors that stim-
ulate the pituitary gland to increase
production of ACTH.
ACTH levels increase in response to
stress, emotion, injury, burns, infection,
surgery, and decreased blood pressure.
Cancerous tumours, particularly those
of the lung, can sometimes produce a
chemical that is similar to ACTH and
which causes symptoms.
DISORDERS OF ACTH PRODUCTION
A tumour of the pituitary gland can
cause excessive production of ACTH,
which, in turn, leads to overproduction
of hydrocortisone by the adrenal cor-
tex, resulting in
hormonal disorder). Insufficient ACTH
production results in decreased pro-
(low blood pressure).
Synthetic ACTH was once given in the
or to treat
but it is now rarely used.
that, together with myosin
protein), provides the mechanism for
muscles to contract. The microscopic
filaments of actin and myosin slide in
between each other to make the muscle
Impulsive actions that may reflect an
individual’s unconscious wishes. The
term is most often used by psycho-
therapists to describe behaviour during
analysis when the patient “acts out”,
rather than reports, his or her fantasies,
wishes, or beliefs. Acting out can also
encountered in everyday life, often tak-
ing the form of antisocial, aggressive
behaviour that may be directed against
oneself or others.
Relating to changes caused by the ultra-
violet rays in sunlight, as in actinic
(inflammation of the skin) and
(roughness and thick-
ening of the skin). Both are caused by
overexposure to solar radiation.
caused by ACTINOMYCES
ISRAELII or related actinomycete bacteria.
cause diseases of the mouth, jaw, chest,
TYPES AND CAUSES
The most common form of actinomy-
cosis affects the jaw area. A painful
swelling appears and pus and char-
through small openings that develop in
the skin. Poor oral hygiene may con-
tribute to this form of the infection.
Another form of actinomycosis affects
the pelvis in women, causing lower
abdominal pain and bleeding between
menstrual periods. This form was asso-
ciated mainly with a type of
longer in use, that did not contain cop-
per. Rarely, forms of the disorder affect
the appendix or lung.
Actinomycosis is usually treated suc-
A derivative of
pressure is applied instead of needles.
A branch of
needles are inserted into a patient’s skin
as therapy for various disorders, to
relieve pain or to induce
Traditional Chinese medicine main-
tains that the
known as meridians. A blockage in one
or more of these meridians is thought
to cause ill health. Acupuncturists aim
to restore health by inserting needles at
appropriate sites, known as acupuncture
points, along the affected meridians.
HOW IT WORKS AND WHY IT IS DONE
provokes the release within the central
stances resembling morphine), which
act as natural analgesics (painkillers).
The disorder that is being treated and
degree of anaesthesia required deter-
mine the needle temperature, place of
insertion, whether the needles are stim-
ulated by rotation or electric current,
and the length of time the needles
remain in position.
anaesthetic for surgical procedures as
well as to provide pain relief following
operations and for chronic conditions.
acupuncture is also claimed to help in
the treatment of addiction, depression,
After treatment with acupuncture, some
people experience temporarily exacer-
bated symptoms. Other people may feel
lightheaded, drowsy, or exhilarated for
a short while.
It is important that acupuncture is
performed by a fully qualified acupunc-
turist because the use of inadequately
sterilized needles could result in the
transmission of a variety of infections,
A term often used to describe a disorder
or symptom that develops suddenly.
Acute conditions may or may not be
severe, and they are usually of short
duration. (See also
acute heart failure
heart failure, acute.
A diagnostic term meaning without
a bluish coloration of the skin
that is seen when blood
abnormally low. The term is commonly
used in relation to the classification of
congenital (present from birth) heart
heart disease, congenital).
The projection at the
neck, just beneath the skin, that is
formed by a prominence on the thyroid