Webster's New World Medical Dictionary

intestine, small
The tubelike organ that receives
the products of digestion from the stomach. It has
three parts: the duodenum, the jejunum, and the
ileum. The duodenum is rich in glands that produce
digestive enzymes, and it also receives bile from the
liver. Digested material moves from the duodenum
to the ileum through the jejunum. The ileum ends
with the ileocecal valve, which prevents food passed
into the large intestine from traveling back into the
small intestine. The walls of the small intestine are
muscular and contract to move digested food along
its length. The intestinal tube is lined with a mucus-
like tissue that contains tiny, finger-like projections
called villi. The villi increase the surface available
for absorbing nutrients from digested food. See also
intestine; intestine, large.
intolerance, food
Difficulty in digesting a food.
Common offenders include milk products, wheat
and other grains that contain gluten, and foods that
tend to cause intestinal gas, such as cabbage and
beans. Food intolerance is often mistaken for food
allergy, but it does not involve a histamine response
against the food. Treatments include avoiding the
offending food and taking supplemental products
that allow that food to be adequately digested.
intolerance, lactose
See 
lactose intolerance.
intra-
Prefix indicating within.
intra-arterial pressure
See 
arterial tension.
intracranial hemorrhage
Bleeding inside the
head. Intracranial hemorrhage can be caused by
many conditions including head injury, ruptured
aneurysm, and stroke.
intractable
Unstoppable. For example, intractable
diarrhea is diarrhea that can’t be stopped, even with
medication, and intractable pain is pain that can’t be
stopped, even with medication.