lymphatic vessels and nerves that supply the small intestine. Another peri-
toneal fold, the mesocolon (Figure 11.4), has similar functions with respect
to the large intestine. The mesentery and mesocolon anchor the intestines
in place but only loosely, allowing them considerable movement as muscu-
lar activities mix and move the contents through the GIT.
The pancreas is found near the stomach and small intestine (Figure 11.1(A)
and (B)) and functions as both an exocrine and an endocrine gland. In its exo-
crine role it produces pancreatic juice that is released into the first part of the
small intestine, the duodenum, through the pancreatic duct. This secretion
contains precursors of digestive enzymes that are activated and function in
the GIT, and also hydrogen carbonate (HCO 3 – ) that increases the pH of GIT
contents. This latter function is vital since the material leaving the stomach
is acidic. The pancreas produces about 1200–1500 cm^3 of pancreatic juice per
Figure 11.2Outline of the tissue organization of the walls of (A) the stomach and (B) the small intestine.
THE GASTROINTESTINAL TRACT AND ITS ACCESSORY ORGANSCZhhVg6]bZY!BVjgZZc9Vlhdc!8]g^hHb^i]:YLddY ',.
MucosaSerosaSubmucosaMuscularis mucosaMuscularisGastric pitBlood vesselA) B)
VilliCrypt of
LieberkuhnLactealLiverStomachColonPeritoneumSmall intestine
MesenteryAbdominal cavityFigure 11.3Schematic showing the peritoneum.