C

cecum The first segment of the COLON (large
intestine) into which the ILEUM, the final segment
of the SMALL INTESTINE, empties digestive matter.
The cecum is a pouchlike structure located in the
lower right abdomen that absorbs water from the
waste, returning fluid to the body and consolidat-
ing the waste for its journey through the end stage
of digestion. The rhythmic contractions of PERI-
STALSISmove the remaining solid waste into the
remainder of the colon. The APPENDIXextends from
the bottom of the cecum.
For further discussion of the cecum and the
colon within the context of gastrointestinal struc-
ture and function, please see the overview section
“The Gastrointestinal System.”
See also ANUS; RECTUM.

celiac disease A condition affecting the SMALL
INTESTINEin which consuming foods that contain
gluten, a plant protein prominent in wheat, trig-
gers an inflammatory response that prevents the
intestinal mucosa (lining) from absorbing NUTRI-
ENTS. Gluten, and more specifically proteins it con-
tains called gliadins, acts as an ANTIGENto initiate a
localized IMMUNE RESPONSE. Researchers believe
celiac disease has a genetic foundation, though the
specific GENEor genes responsible remain undeter-
mined. Though severe celiac disease can cause sig-
nificant NUTRITIONAL DEFICIENCIESthat affect growth,
FERTILITY, and overall health, most people who
adopt a gluten-free diet are able to avert the
inflammatory episodes and minimize damage to
the intestinal mucosa. About 1 in 5,000 Ameri-
cans has celiac disease.

Symptoms and Diagnostic Path

Symptoms appear in celiac disease with exposure
to gluten, so usually do not become apparent until

after the age of two years when children begin

eating solid foods. People who have celiac disease

experience a broad range of symptoms, with some

people having virtually no indications they have

celiac disease until nutritional deficiencies become

problematic and other people suffering chronic

DIARRHEA, cramping, ABDOMINAL DISTENTION, and

other gastrointestinal disruptions. Some people

have outbreaks of DERMATITIS herpetiformis, an

itchy SKIN RASH. An early indication of celiac dis-

ease, especially in children, is the passing of large,

loose, light-colored, foul-smelling stools, which

suggests high fat excretion (STEATORRHEA) charac-

teristic of MALABSORPTION.

Celiac disease may affect any or all of the seg-

ments of the small intestine, and the degree to

which it affects them determines the symptoms.

Many of the symptoms and signs of celiac disease

arise from health problems due to nutritional defi-

ciencies that correlate to the segment of small intes-

tine affected, manifesting in conditions such as

ANEMIA(deficiency of iron, suggesting involvement

of the DUODENUMand upper JEJUNUM) and frequent

nosebleeds (deficiency of VITAMIN K, suggesting

involvement of the lower jejunum and the ILEUM).

Children who have celiac disease may also appear

malnourished, showing spindly limbs and protrud-

ing bellies, despite adequate food consumption.

Biopsy of the intestinal mucosa in people who

have celiac disease tends to show marked struc-

tural differences from normal intestinal mucosa.

Most significant is flattening of the mucosal tissue

from its normal “pleated” appearance, which

reduces the surface area available for nutrient

absorption. Lymphocytes and leukocytes are also

present within the mucosal tissue, evidence of the

inflammatory process. However, there are no

definitive tests to diagnose celiac disease. BLOOD

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