Pancreas

Structure and Function

Structure

It's a 15cm long exocrine and endocrine gland. It's an elongated structure that lies in the epigastrium and left upper quadrant. It is soft and lobulated and is retroperitoneal. It crosses the transpyloric plane.

The pancreas is divided into a head, neck, body and tail. Part of the head extends to the left behind the superior mesenteric vessels and is called the uncinate process, whilst the tail passes into the splenicorenal ligament and comes in contant with the hilum of the spleen.

Functions

Exocrine

Produces enzymes capable of digesting fats, lipids and proteins:

• Trypsinogen – type of zymogen granule
• Pancreatic amylase
• Pancreatic lipase.

It also has ductal cells which secrete bicarbonate ions. Secretions are controlled by Cholescystokinin (CCK), secretin and gastrin. The more of those hormones there are about the more the pancreatic secretions are.

Endocrine

Produces hormones in the islets of langerhans, in three different cells:

• Alpha – secret glucagons; which performs glycogen -> glucose
• Beta – secrete insulin; glucose -> glycogen
• Delta - secrete somatostatins; it's the "party pooper" of all hormones, cos it reduces glucagons, insulin and growth hormone.
• PP Cells – secrete pancreatic polypeptide.
• Enterochromaffin – produce serotin.

Arterial and Venous supply

The splenic artery supplies the tail of the pancreas through a few random branches.

The superior and inferior pancreaticoduodenal arteries supply the head and body and it all drains back into the portal, via the pancreaticoduodenal veins. This is cool, when you realise that that means hormones, like insulin, get sent straight to the liver.

Nervous Supply

Sympathetic and parasympathetic (vagal) nerves supply the gland, and eventually drain into the celiac and superior mesenteric nodes.