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Pancreas

Overview of the Pancreas

  • The pancreas is a dual-function organ (both exocrine and endocrine) located in the retroperitoneal space. It is a vital gland that helps regulate blood sugar and aids in digestion.

Anatomy of the Pancreas

  • Location:

    • Lies deep in the epigastrium and left hypochondrium.

    • Bounded anteriorly by the stomach and the duodenum.

  • Shape and Size:

    • Comma-shaped, approximately 12 cm long and 2 cm thick.

    • Non-encapsulated, extends from the concavity of the duodenum to the hilum of the spleen.

Functions

Endocrine Function

  • Hormones: The pancreatic islets (Islets of Langerhans) produce important hormones:

    • Alpha Cells: Secrete glucagon which raises blood sugar levels.

    • Beta Cells: Secrete insulin which lowers blood sugar levels.

    • Delta Cells: Secrete somatostatin, which regulates the endocrine system and inhibits hormone secretion.

  • Function is to control blood sugar levels.

Exocrine Function

  • Digestive Enzymes: Acinar cells secrete:

    • Amylase: Breaks down carbohydrates.

    • Lipase: Breaks down fats.

    • Trypsin: Breaks down proteins.

    • Sodium bicarbonate: Neutralizes stomach acid.

  • Duct System:

    • Enzymes drain into the main pancreatic duct (duct of Wirsung), then to the ampulla of Vater where they mix with bile and enter the duodenum through the sphincter of Oddi.

Anatomy Parts of the Pancreas

Five Parts

  • Uncinate Process: Extension of the head, variable in size, located behind the superior mesenteric vessels.

  • Head: Lies in the duodenal C-loop; anterior to IVC and inferior to portal vein.

  • Neck: Site for the passage of superior mesenteric vessels; forms the portal vein with the splenic vein.

  • Body: Largest part, located posterior to the stomach and anterior to the portal vein.

  • Tail: Anterior to the left kidney, close to the spleen.

Imaging the Pancreas

  • Transverse Ultrasound: Demonstrates the relations of the pancreatic head, uncinate process, and neck.

  • Sagittal Sections: Provide views of the head, neck, body, and tail for vascular landmarks.

Vascular Supply

  • Arterial Supply:

    • Head supplied by the gastroduodenal artery.

    • Body and tail by the splenic artery and superior mesenteric artery.

  • Venous Drainage:

    • Drains to the portal vein, splenic vein, superior mesenteric vein, and inferior mesenteric vein.

Duct Systems

Main Ducts

  • Wirsung’s Duct: Main pancreatic duct along the length of the pancreas, opens into duodenum at Vater’s ampulla.

  • Santorini’s Duct: Secondary duct draining the upper anterior head, enters the duodenum at the minor papilla.

Normal Measurements

  • Pancreas:

    • Head: 2.0 - 2.5 cm AP

    • Body: 1.0 - 1.5 cm AP

    • Tail: 0.5 - 3.0 cm AP

  • Duct: Typically around 2 mm; becomes narrower towards the tail.

Congenital Anomalies

  1. Pancreas Divisum: Failure of ducts to fuse leading to separate drainage.

  2. Anular Pancreas: Pancreatic tissue surrounds the duodenum, potentially causing stenosis.

  3. Ectopic Pancreas: Pancreatic tissue found in areas like the stomach, duodenum, or umbilicus.

  4. Intraperitoneal Pancreas: Involves parts of pancreas being found within the peritoneal cavity.

Ultrasound Scanning Techniques

  • Patients should fast for 6-8 hours to enhance imaging by reducing bowel gas and promoting dilation of the gallbladder and ducts.

  • Indications for Scanning:

    • Epigastric pain, weight loss, jaundice, diarrhea, bloating, new-onset diabetes.

Summary

  • The pancreas plays crucial roles in both digestion and hormonal regulation, with a complex structure and important relationships with surrounding organs and vasculature.