12-2 Pathology of the Pancreas (Liver Path 7) Flashcards
(118 cards)
What are the 2 main functional components of the pancreas (excluding ducts and other conducting stuff)?
Exocrine and Endocrine pancreas
What is the exocrine pancreas? How much of the pancreas does it take up, and what does it do?
Exocrine pancreas constitutes 80% to 85% of the organ
composed of acinar cells that
secrete enzymes needed for digestion. (~1.5L of secretions)
How much of the pancreas is taken up by the other functional component, the endocrine pancreas? What does it make?
Endocrine pancreas is composed of about 1 million clusters of cells, the islets of Langerhans.
Islet cells secrete insulin, glucagon and somatostatin and constitute only 1% to 2% of the organ.
Pancreatic development frequently gives rise to congenital variations in pancreatic anatomy. What is the most common anomaly?
Pancreas divisum is the most common congenital anomaly of the pancreas where there is a failure of fusion of the fetal duct systems of the dorsal and ventral pancreatic primordia leaving most of the pancreas being drained by a limited duct system.
Explain how the most common congenital anomaly of the pancreas, pancreas divisum, is different from normal anatomy of the pancreas.
Normal pancreas - pancreas is efficiently drained by the main pancreatic duct, the duct of Wirsung. This joins the common bile duct just proximal to papilla of Vater. The accessory pancreatic duct drains the rest of the pancreas, and has it’s own minor papilla.
Pancreas divisum - most of the pancreas is drained through a limited duct system into the minor papilla
In addition to pancreas divisum, what other common congenital anomalies of the pancreas exist?
•Annular pancreas can be associated with duodenal obstruction
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•Ectopic pancreas - sites: Stomach, duodenum, jejunum, ileum are sites of ectopic pancreas usually very small or microscopic
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•Agenesis (very rare)
What is this image of a normal pancreas trying to show?
2 main fxn’al domains of the pancreas
- endocrine pancreas are the clusters of smaller cells (Islets of Langerhan) that stain lightly, and make up a minority of total mass
- exocrine is the larger, darker staining, majority of cells that secrete digestive enzymes that go into the duodenum just proximal to pancreas
What functional part of the pancreas does the blood supply go to first?
Much of the blood coming to the pancreas goes to the islets first, then to the acinar cells
What do alpha and beta cells do?
The alpha- and beta-cells regulate the usage of glucose through the production of glucagon and insulin, respectively.
What leads to DM1?
Autoimmune destruction of islet beta cells triggered by a virus or some other factor, leads to Type 1 diabetes mellitus
How are digestive enzymes secreted from the pancreas? What is the stimulus, and how are they secreted?
Enzymatic secretion is mediated by stimulants such as secretin, a hormone released from the duodenum by the introduction of gastric acid, cholecystokinin (CCK), released by the presence of dietary fat, amino acids, hydrochloric acid, and acetylcholine, which is produced as a response to the sensory aspects of feeding and to the physical effects of chewing and swallowing. Upon binding of specific receptor sites on the acinar membrane with CCK or acetylcholine, the zymogen granules migrate to the apex of the acinar cell, where they are extruded into the central ductal lumen
Why does this pic of normal pancreatic tissue have a bunch of cells that look grainy?
Depicts pancreatic acinar cells
These cells have basally located nuclei and numerous zymogen granules at their apical pole. They also have abundant endoplasmic reticulum in the basal portion of the cytoplasm. These cells will secrete their granule contents into the lumen of the duct, which will carry the enzymes out of the pancreas and to the duodenum
When you picture an SEM photograph of pancreatic acinar cells secreting zymogens, what does it look like?
Something like this:
have basally located nuclei and numerous zymogen granules at their apical pole. They also have abundant endoplasmic reticulum in the basal portion of the cytoplasm. These cells will secrete their granule contents into the lumen of the duct, which will carry the enzymes out of the pancreas and to the duodenum
Why are so many pancreatic enzymes synthesized and stored as zymogens?
•Pancreatic enzymes such as trypsinogen are synthesized and stored in an inactive form, and are activated upon release into the lumen of the duodenum via the action of enterokinases.
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Premature activation of these enzyme precursors results in autodigestion of the surrounding tissues and triggers an inflammatory chain response
What is acute pancreatitis?
Autodigestion of the pancreas by its own enzymes (inappropriate activation of digestive proenzymes)
What is the autodigestion process in acute pancreatitis often initiated by?
•initiated by:
–Alcohol (65% in US)
–Pancreatic duct obstruction (calculi) (20%)
–Drugs (furosemide, associated with HIV treatment)
–Vascular injury (ischemia)
–Infections (viruses including mumps)
–Hereditary factors (Hereditary pancreatitis)
–Hypercalcemia
What is the mortality rate for acute pancreatitis?
~10% on average
When does alcoholic pancreatitis occur?
•In people with alcoholic pancreatitis, the symptoms of acute pancreatitis often occur one to three days after an alcohol binge or after stopping drinking.
What is hereditary pancreatitis?
•Hereditary pancreatitis characterized by recurrent attacks of severe acute pancreatitis beginning in childhood and the development of chronic pancreatitis. Trypsin appears to be resistant to self inactivation. Increased risk for cancer (25-40%)
How is acute pancreatitis treated?
•Acute pancreatitis can be treated by medical management including supportive care with fluid replacement, pain relief and reduction of pancreatic secretions by avoidance of food.
What is the progression and prognosis of acute pancreatitis?
- Most attacks of acute pancreatitis do not lead to complications, and most people recover uneventfully with medical care.
- A small proportion of people have a more serious illness that requires intensive medical care.
What contributes to the development and recurrence of pancreatitis?
A complex combination of genetic, environmental, and metabolic factors contribute to the development and recurrence of acute and chronic pancreatitis
–Multiple lines of evidence indicate that premature activation of trypsin in acinar cells damages the cells causing inflammatory response recognize clinically as acute pancreatitis
–Many different genetic factors affect acinar cell function, bile duct function, trypsin inactivation and intensity of a immune response in the pancreas
What is the peak age range for acute pancreatitis?
•Peak age range for initial episode is 35 to 44 yrs
What serum components are helpful in making a dx of acute pancreatitis? How accurate are they?
- Serum amylase rises within 6 to 12 hours of the onset of acute pancreatitis. (Moderate sensitivity, high specificity)
- Serum lipase rises within 4 to 8 hours of onset of acute pancreatitis (high sensitivity and specificity)
