The pancreas is a gland with both exocrine and endocrine functions.
The exocrine pancreas contains acini, which secrete
pancreatic juice into the duodenum through the pancreatic ducts
(Figure 15–1). Pancreatic juice
contains a number of enzymes, some of which are initially made in
an inactive form. Once activated, these enzymes help to digest food
and prepare it for absorption in the intestine. Disorders interfering
with normal pancreatic enzyme activity (pancreatic insufficiency) cause
maldigestion of fat and steatorrhea (fatty stools). Dysfunction
of the exocrine pancreas results from inflammation (acute pancreatitis,
chronic pancreatitis), neoplasm (ductal adenocarcinoma, neuroendocrine
tumors, and other pancreatic neoplasms), or duct obstruction by
stones or abnormally viscid mucus (cystic fibrosis).
Anatomy of the pancreas. (Courtesy of W. Silen.)
(Redrawn, with permission, from Way LW [editor]. Current Surgical
Diagnosis & Treatment, 10th ed. Originally published by
Appleton & Lange. Copyright © 1998 by the McGraw-Hill Companies,
The endocrine pancreas is composed of the islets of Langerhans. The
islets are distributed throughout the pancreas and contain several
different hormone-producing cells. The islet cells manufacture hormones
such as insulin that are important in nutrient absorption, storage,
and metabolism. Dysfunction of the endocrine pancreas causes diabetes
mellitus (see Chapter 18).
Both exocrine and endocrine pancreatic dysfunction occur together
in some patients.
The pancreas is a solid organ that lies transversely in the retroperitoneum
deep within the epigastrium. It is firmly fixed by fibrous attachments
anterior to the suprarenal aorta and the first and second lumbar
vertebrae. Thus, the pain of acute or chronic pancreatitis is situated
deep in the epigastric region and frequently radiates to the back.
Normally, the pancreas is about 15 cm long, although it weighs
less than 110 g. The organ is covered by a thin capsule of connective
tissue that sends septa into it, separating it into lobules.
The pancreas can be divided into four parts: head, including
the uncinate process; neck; body; and tail. The head is the thickest
part of the gland (2–4 cm) and lies in the curved space
between the first, second, and third portions of the duodenum. The
uncinate process is the portion of the head that extends to the
left behind the superior mesenteric vessels. The neck connects the
head and body and sits immediately anterior to the superior mesenteric
vessels. The body is situated transversely in the retroperitoneal
space, bordered superiorly by the splenic artery and posteriorly
by the splenic vein. The tail of the pancreas is less fixed in the
retroperitoneum and extends toward, and often immediately adjacent
to, the hilum of the spleen.
Embryologically, the pancreas develops as two separate endodermal
buds from the developing foregut. These separate dorsal and ventral
elements of the primordial pancreas initially develop opposite each