1.11 Structure and Function of Pancreas

The pancreas is a gland with both endocrine and exocrine functions. Anatomically, it is divided into a head, neck, body, and tail. The endocrine function is carried out by the pancreatic islets (islets of Langerhans), while the exocrine function involves the secretion of digestive pancreatic juice.

Anatomy of the Pancreas

The pancreas is an elongated organ located in the abdomen.

• Head: The widest part, situated in the C-shaped curve of the duodenum (first part of the small intestine).
• Neck: A short section connecting the head and the body.
• Body: The central part of the pancreas, located behind the stomach.
• Tail: The narrow end, extending towards the spleen.

Pancreas as an Exocrine Gland

The exocrine function of the pancreas is to produce and secrete pancreatic juice, which is essential for digestion in the small intestine.

Aqueous Component

• Contains bicarbonate ions ($\mathrm{HC}{\mathrm{O}}_3^{-}$).
• Function: To neutralize the acidic chyme (partially digested food) that arrives from the stomach, creating an optimal pH for digestive enzymes to function.

Enzymatic Component

• Contains a variety of enzymes that digest all major classes of food macromolecules.
• Many of these enzymes, especially those that digest proteins, are secreted in an inactive form called zymogens to prevent them from digesting the pancreas itself.

Pancreatic Digestive Enzymes

Enzyme Activation Cascade: The process is initiated by enterokinase, an enzyme from the small intestine, which converts inactive trypsinogen into active trypsin. Trypsin then acts as a catalyst to activate other zymogens (chymotrypsinogen and procarboxypeptidase) as well as more trypsinogen.