RECTUM,CANCER OF
REFLEX, PRIMITIVE
rectum, cancer of A cancerous
tumour
in the
rectum.
The cause is unknown,
but dietary factors and genetic factors
are thought to play a part. It is more
common between ages 50 and 70.
Early symptoms are
rectal bleeding
during defecation and diarrhoea or con-
stipation. Later, pain may occur. Left
untreated, the cancer may eventually
cause severe bleeding and pain and
block the intestine. It may also spread
to other organs.
The cancer may be detected by a
rectal
examination
and confirmed with
proc-
toscopy
or
sigmoidoscopy
and
biopsy.
Treatment is usually with surgery. For a
tumour in the upper rectum, the affected
area and the last part of the colon are
removed and the
2
free ends of the
intestine are sewn together. To promote
healing, a temporary
colostomy
may be
made. For a growth in the lower rectum,
the entire rectum and anus are removed.
Because there is no outlet for faeces, a
permanent colostomy is created.
Radiotherapy
and
anticancer drugs
may
be used in addition to or instead of sur-
gery. Up to 40 per cent of people treated
for rectal cancer live for
10
years or more.
red-eye Another name for
conjunctivitis.
reduction The process of manipulating
a displaced part of the body back into
its original position.
referred pain Pain felt in a part of the
body at some distance from its cause. It
occurs because some remote parts of
the body are served by the same nerve
or group of nerves. Nerve impulses that
reach the brain from one of these areas
may be misinterpreted as coming from
another. A common example of referred
pain is the pain down the left arm
caused by a
myocardial infarction.
reflex An action that occurs automati-
cally and predictably in response to a
particular stimulus, independent of the
will of the individual.
In the simplest reflex, a sensory nerve
cell reacts to a stimulus, such as heat or
pressure, and sends a signal along its
nerve fibre to the
central nervous sys-
tem.
There, another nerve cell becomes
stimulated and causes a muscle to con-
tract or a gland to increase its secretory
activity. The passage of the nerve signal
from original sensation to final action is
called a reflex arc.
Reflexes may be inborn or condi-
tioned. Some inborn reflexes occur only
in babies (see
reflex, primitive
). Inborn
reflexes include those that control basic
body functions, such as contraction of
the bladder after it has filled beyond a
certain point, and are managed by the
autonomic nervous system
. Conditioned
reflexes are acquired through experi-
ence in a process called
conditioning
.
Several simple reflexes, such as the
knee-jerk, are tested in a
physical exam-
ination
. Changes in the reflexes may
indicate damage to the nervous system.
The examination of vital reflexes con-
trolled by the brainstem is the basis for
diagnosing
brain death
.
reflexology A form of
complementary
medicine
in which the practitioner mas-
sages parts of the patient's feet in an
attempt to treat disorders affecting
other areas of the body.
reflex, primitive An automatic move-
ment in response to a stimulus that is
present in newborn infants but disap-
pears during the first few months after
birth. Primitive reflexes are believed to
represent actions that were important in
earlier stages of human evolution. They
include the grasp reflex when something
is placed in the hand and the rooting
reflex, which enables a baby to find the
nipple. The rooting reflex can be evoked
by touching the baby's cheek with the
fingertip. These reflexes are tested after
birth to give an indication of the condi-
tion of the nervous system.
REFLEX, PRIMITIVE
ROOTING REFLEX
483
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