Exocrine Pancreas Function and Structure Quiz

Anatomy of the Exocrine Pancreas

• Located in the retroperitoneal space, extends from the C-loop of the duodenum to the hilum of the spleen.
• Comprises head, neck, body, and tail; approximately 20 cm in length.
• Main pancreatic duct (Wirsung) drains into the duodenum at the papilla of Vater; accessory duct (Santorini) drains through the minor papilla.

Physiology of the Exocrine Pancreas

• Exocrine portion produces 80-85% of the organ, secreting digestive enzymes and 1-2 liters of alkaline fluid daily.
• Digestive juices contain around 20 enzymes, including proteases, lipases, elastases, and amylases; bicarbonate secretion neutralizes acidity.

Histology

• Composed of acinar cells that produce digestive enzymes; ducts transport secretions to the duodenum.
• Acinar cells are pyrimidally shaped, oriented radially, and contain zymogen granules rich in digestive enzymes.

Congenital Anomalies

• Four main congenital abnormalities: agenesis, pancreas divisum, annular pancreas, ectopic pancreas.

Pancreas Divisum

• Most common congenital anomaly; results from the failure of fusion of dorsal and ventral pancreatic ducts.
• Predisposes to chronic pancreatitis due to relative stenosis and overload on the minor papilla.

Annular Pancreas

• A band-like ring of pancreatic tissue encircling the duodenum; may cause duodenal obstruction.

Ectopic Pancreas

• Aberrant pancreatic tissue often located in the stomach, duodenum, jejunum, or Meckel diverticula.
• May cause localized inflammation or mucosal bleeding; 2% can lead to islet cell neoplasms.

Acute Pancreatitis

• Characterized by reversible pancreatic parenchymal injury and inflammation; common condition.

Causes of Acute Pancreatitis

• Metabolic (alcoholism, hyperlipoproteinemia, hypercalcemia), mechanical (gallstones, trauma), vascular (shock), and infectious (mumps).

Pathology of Acute Pancreatitis

• Grossly presents as swollen, hemorrhagic pancreatic tissue; fat necrosis in surrounding areas.
• Microscopically shows variable necrosis and inflammatory cell infiltrate based on severity; neutrophilic infiltrates indicative of inflammation.

Pathogenesis of Acute Pancreatitis

• Main event: autodigestion by activated pancreatic enzymes, primarily trypsin.
• Ductal obstruction, primary acinar cell injury, and defective transport of proenzymes contribute to pathogenesis.
• Alcohol induces chronic inflammation and ductal obstruction through protein-rich secretions.

Clinical Aspects of Acute Pancreatitis

• Intense abdominal pain, anorexia, nausea, and vomiting; may lead to emergency situations like shock or disseminated intravascular coagulation (DIC).
• Diagnosis validated by elevated serum amylase and lipase levels; imaging shows enlarged pancreas.

Management and Prognosis of Acute Pancreatitis

• Management includes "resting" the pancreas with total oral intake restriction and supportive therapy.
• Most recover fully; 5% mortality in severe cases due to shock.

Chronic Pancreatitis

• Inflammation causing irreversible destruction of pancreatic tissue; common in middle-aged males.

Causes of Chronic Pancreatitis

• Chronic alcoholism, long-standing duct obstruction, genetic predispositions, autoimmune conditions, and idiopathic factors.

Pathology of Chronic Pancreatitis

• Macroscopically shows firm, fibrous tissue with loss of lobular architecture, while microscopically exhibits fibrosis and atrophy of acinar cells.

Clinical Aspects of Chronic Pancreatitis

• Symptoms include recurrent abdominal pain, digestive discomfort, and signs of malabsorption or diabetes mellitus development.
• Diagnosis often relies on imaging techniques revealing ductal calcifications and weight loss.

Complications of Chronic Pancreatitis

• Severe exocrine insufficiency, chronic malabsorption, diabetes mellitus, and development of pancreatic pseudocysts.

Prognosis of Chronic Pancreatitis

• Long-term outlook is poor; mortality rate after 20-25 years is approximately 50%.