annular pancreas


Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.

pancreas

 [pan´kre-as] (pl. pancre´ata) (Gr.)
a large, elongated, racemose gland located transversely behind the stomach, between the spleen and duodenum. (See also Plate 11.) It is composed of both exocrine and endocrine tissue. The acini secrete digestive enzymes, and small ductules leading from the acini secrete sodium bicarbonate solution. The combined product, pancreatic juice, enters a long pancreatic duct and from there is transported through the hepatic duct to the duodenum. The pancreatic juice contains enzymes for the breakdown of proteins, carbohydrates, and fats. The bicarbonate ions in the pancreatic secretion help neutralize the acidic chyme that is passed along from the stomach to the duodenum.

Regulation of pancreatic secretion of enzymes and bicarbonate ions is both neural and hormonal; however, the influences of the hormones secretin and cholecystokinin are more important than vagal stimulation. The entry of chyme into the small intestine causes the transformation of an inactive proenzyme, prosecretin, into active secretin that is released from the mucosa of the upper portion of the duodenum. The composition of the partially digested food entering the duodenum influences the amount of each hormone that is released and, therefore, the characteristics of the pancreatic juice.

The endocrine functions of the pancreas are related to the islets of Langerhans located on the surface of the pancreas. These small islands contain three major types of cells: the alpha, beta, and delta cells. The alpha cells secrete the hormone glucagon, which elevates blood sugar. The beta cells secrete insulin, which affects the metabolism of carbohydrates, proteins, and fats. The delta cells secrete somatostatin, the functions of which are not fully understood, but it is known that it can inhibit the secretion of both glucagon and insulin and may act as a controller of metabolic processes. The somatostatin produced by the delta cells of the pancreas is the same as that produced by the hypothalamus as an inhibitor of the release of growth hormone from the pituitary gland.
Disorders of the Pancreas. Failure of the islets of Langerhans to produce sufficient amounts of insulin results in diabetes mellitus. Disturbances in the exocrine functions of the pancreas produce serious digestive disorders. The pancreas can also be the seat of cancerous growth, and occasionally the pancreatic ducts are blocked by stones. Various factors, not yet fully understood, may result in acute pancreatitis, a condition in which the fluids digest the tissue of the organ itself. cystic fibrosis, a serious congenital disease, is characterized by a deficiency in the secretion of pancreatic juice, and an increase in its viscosity.
The anatomical relations of the pancreas. From Aspinal and Taylor-Robinson, 2001.
annular pancreas a developmental anomaly in which the pancreas forms a ring entirely surrounding the duodenum.

annular pancreas

An extremely rare finding in which a flat band of pancreatic tissue surrounds the D2 part of the duodenum, causing partial or complete obstruction of the upper GI tract. Complete duodenal obstruction is detectable in the neonatal period, while partial obstruction may remain undetected into adulthood.
 
Clinical findings
Nausea, vomiting.

Associated anomalies
Duodenal bands, intestinal malrotation, Meckel’s diverticulum, cryptorchidism, cardiac and spinal cord defects; up to 20% have Down syndrome.

Aetiology
Unknown.

Diagnosis
Upper GI series, abdominal CT, endoscopy.
 
Management
Surgical.
 
Complications
Peptic ulcer disease, perforation.

annular pancreas

An anomalous condition in which a portion of the pancreas encircles the duodenum.
See also: pancreas
References in periodicals archive ?
Annular pancreas in adults: Imaging features in seven patients.
Both of the 2 main theories as to how annular pancreas develops involve the left and right ventral buds that normally form the head and neck of the pancreas.
Differential diagnosis of this sign, detected either prenatally or postnatally, includes duodenal atresia, annular pancreas, duodenal stenosis, duodenal webs, and midgut volvulus.