Webster's New World Medical Dictionary

galactosylceramidosis
See 
Krabbe disease.
gallbladder
A pear-shaped organ located below
the liver that stores the bile secreted by the liver.
During and after a fatty meal, the gallbladder con-
tracts, delivering the bile through the bile ducts into
the intestines to help with digestion.
gallbladder absence
See 
agenesis of the gall-
bladder.
gallium
A rare metal with the atomic weight 69.
There are several isotopic forms of gallium that dif-
fer from it in atomic weight. One is gallium-68,
which is produced by cyclotrons and emits gamma
rays. The citrate form of gallium-68 is used as a
radiotracer to locate sites of inflammation and
tumor tissue within the body.
gallium scan
A test to detect sites in the body
where cells are multiplying rapidly, such as tumors
or areas of inflammation. A small amount of
radioactive gallium is injected into a vein, and the
element is taken up by cells that are rapidly divid-
ing. A scanner is used to detect the areas of gallium
uptake. See also 
gallium.
gallop rhythm
An abnormal heart rhythm that
pounds in the chest resembling the gallop of a horse
when heard during examination with a stethoscope.
gallstone
A stone of varying size that forms when
substances in bile harden. There can be just one
large stone, hundreds of tiny stones, or any combi-
nation and number. Gallstones can block the normal
flow of bile if they lodge in any of the ducts that carry
bile from the liver to the small intestine. Bile trapped
in these ducts can cause inflammation in the gall-
bladder, the ducts, or, rarely, the liver. If a gallstone
blocks the opening to the pancreatic duct, which
opens into the common bile duct, digestive enzymes
can become trapped in the pancreas and cause
extremely painful inflammation called gallstone pan-
creatitis. Gallstones may not cause symptoms or may
lead to pain for up to several hours in the upper
back or under the right shoulder, together with nau-
sea, vomiting, abdominal bloating, or indigestion.
There are two types of gallstones: cholesterol stones
and pigment stones. Gallstones are most common
among women, Native Americans, Mexican
Americans, and people who are overweight.
Laparoscopic surgery to remove the gallbladder is
the most common treatment. Also known as
cholelithiasis.