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Pancreatic Function. Lecture 19. The Pancreas. Pancreas is a large gland Involved in the digestive process but located outside the GI tract Composed of both exocrine and endocrine functions 15-25 cm in length 60-100 gram in weight. Types of Tissues. Two functionally different tissues:
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Pancreatic Function Lecture 19
The Pancreas • Pancreas is a large gland • Involved in the digestive process but located outside the GI tract • Composed of both exocrine and endocrine functions • 15-25 cm in length • 60-100 gram in weight
Types of Tissues • Two functionally different tissues: • Endocrine (hormone releasing) • The smaller component • consists of islet of langerhans – 4 cell types • Secrete 4 hormones • Insulin, glucagon, ghrelin & somatostatin • Exocrine (enzyme secreting) • The larger component • secrets 1.5 – 2 L/day, rich in digestive enzymes • has alkaline pH due to its content of NaHCO3 • Produced by pancreatic acinar cells
Somatostatin Glucagon Insulin
Functions • Completes the job of breaking down food using digestive enzymes of pancreas • Protein → trypsin, chymotrypsin • Carbohydrates → amylase • Fats → lipase, lecithinase • Secretes hormones that affect the level of sugar in the blood. • Insulin, glucagon • Produces chemicals that neutralize stomach acids that pass from the stomach into the small intestine • NaHCO3 • Most of the pancreatic action is under the hormonal control of secretin and Cholecystokinin
Pancreatic disorders • The major disorders of the pancreas are: • Endocrine pancreas: • Diabetes Mellitus (DM) • Islet Cell Tumors • Exocrine pancreas: • Acute pancreatitis & chronic pancreatitis • Pancreatic cancer • Cystic fibrosis
Islet Cell Tumors • Tumors of the pancreatic islets are rare in comparison with tumors of the exocrine pancreas. • Islet cell tumors of the pancreas affect endocrine capability • If tumor occurs in beta cells → hyperinsulinism → low blood sugar • Alpha cell tumors → ↑ glucagon → DM
Pancreatitis • Inflammation of the pancreas • The exocrine pancreas produces a variety of enzymes, such as proteases, lipases, and saccharidases. • These enzymes start auto-digestion of the pancreas which causes the pain and complications of pancreatitis. • About 80% of cases are associated with cholelithiasis and alcoholism. • Associated with raised levels of pancreatic enzymes (amylase and lipase) in blood and urine.
Laboratory Findings • Marked elevation of the serum amylase during the first 24 hours, followed within 72-96 hours by a rising serum lipase. • Hypocalcemia
Pancreatic Cancer • Carcinoma of the pancreas refers to carcinoma of the exocrine pancreas • Almost always arising from ductal epithelial cells (adenocarcinoma). • Presentation often occurs as a result of metastases rather than as a direct effect of the primary tumor.
Laboratory Finding • Tumor markers, include: • carcinoembryonic antigen (CEA), • CA 19-9, • and CA 125, • All are associated with pancreatic cancer but are nonspecific and can be elevated in conditions other than malignancies
Cystic Fibrosis • Cystic fibrosis is an inherited, autosomal recessive disease that affects nearly all exocrine glandsin the body. • The disease is characterized by: • chronic obstructive pulmonary disease, • pancreatic insufficiency, • and abnormally high sweat electrolytes. • The disease causes the exocrine glands to become obstructed by viscous material. • The blockage leads to cellular damage within the tissue. • Pancreatic insufficiency leads to poor digestion and poor growth pattern with a deficiency of fat-soluble vitamins.
Cystic Fibrosis • CF is caused by a mutation in the gene for the protein cystic fibrosis transmembrane conductance regulator (CFTR). • This gene is required to regulate the components of sweat, digestive juices, and mucus. • The diagnosis of cystic fibrosis is made by clinical symptoms and positive sweat chloride test. • People with cystic fibrosis have unusually large amounts of chloride in their sweat when compared to reference ranges of healthy individuals. • The sweat is collected on sterile gauze over a period of a few minutes and later analyzed for the amount of chloride present. • Genetic analysis can be used to counsel families for gene carrier status.
Other Tests • Detection of malabsorption • Fecal fat test • Indicates either pancreatic dysfunction or intestinal malabsorption • D-xylose absorption test • A pentose sugar which does not require pancreatic enzymes for absorption • In normal individuals, a 25 g oral dose of D-xylose will be absorbed and excreted in the urine at approximately 4.5 g in 5 hours.
Other Tests • Measuring exocrine function • Secretin, chymotrypsin, trypsin, cholecystokinin • Measuring endocrine function • insulin, glucose
Case Study • A 38-year-old man entered the emergency department with the complaint of severe, mid abdominal pain of 6 hours' duration. • The patient had a 15-year history of alcoholism • He had last been hospitalized for acute alcoholism 3 months ago, at which time he had relatively minor abnormalities of liver function. • On this admission, his blood pressure was 80/40 mm Hg;
What is the probable disease? • Acute pancreatitis
What is the cause for the low serum calcium? • Enzymatic fat necrosis and digestion, which result in free fatty acids in abdominal adipose tissue. The fatty acids then bind calcium as they form fatty acid salts. • What is the cause for the increased blood urea nitrogen? • Shock, resulting in prerenal azotemia