Essentials of Anatomy and Physiology

presence of food in the duodenum. The intestinal
enzymes are the peptidases and sucrase, maltase, and
lactase. Peptidasescomplete the digestion of protein
by breaking down short polypeptide chains to amino
acids. Sucrase, maltase, and lactase, respectively,

digest the disaccharides sucrose, maltose, and lactose

to monosaccharides.

The enteroendocrine cells of the intestinal glands

secrete the hormones of the small intestine. Secretion

is stimulated by food entering the duodenum.

382 The Digestive System

Pyloric sphincter

Hepatic duct

Cystic duct

Duodenum

Main

pancreatic

duct

Pancreas

Superior mesenteric

artery and vein

Islets of

Langerhans

Ducts

Acini

Capillaries

Delta cell

Beta cell

Alpha cell

A

B

Common

bile duct

Ampulla of Vater

Figure 16–7. (A) The pancreas, sectioned to show the pancreatic ducts. The main pan-

creatic duct joins the common bile duct. (B) Microscopic section showing acini with their

ducts and several islets of Langerhans.

QUESTION:In part B, what do the acini secrete?