Flashcards in Exam #5: Pancreas Deck (22):
What are the three key cell types that are important to the exocrine function of the pancreas?
1) Acinar cells= protein synthesis
2) Duct cells= fluid & bicarbonate
3) Goblet cells mucin synthesis & secretion
What are the acinar cells of the pancreas? What is the function of the acinar cells of the pancreas?
Acinar cells are the protein synthesizing cells that:
- Secrete digestive enzymes
- Secrete fluid
What are duct cells & what do they produce?
Duct cells are cells lining the ducts of the pancreas that function in:
- Bicarbonate secretion
- Ion transport
- Fluid transport
Generally, the duct cells have a product that is PROTECTIVE
What are goblet cells & what do they produce?
Goblet cells produce mucin that:
- immune function
What are the two primary stimuli for fluid and enzyme secretion by pancreatic acinar cells?
*****CCK & ACh
- CCK promotes fluid & enzyme secretion (which is enhanced by VIP or secretin)
*****Note that these two signals also promote the secretion of cholride, leading to Na+ & H20 accumulation in the lumen of the pancreatic ducts
What are the zymogens produced by the pancreas? How are zymogens stored in the pancreas?
*****These are inactive proteases in the pancreas
How are zymogens activated in the duodenum?
- Secreted in an inactive form & travel from: 1) pancreatic duct, 2) common bile duct, 3) duodenum
- In duodenum, trypsinogen is converted to trypsin via enterokinase that is secreted by duodenal cells; trypsin activates the other proteases
What is the primary stimulus for the secretion of bicarbonate from the pancreatic duct cells?
****Secretin action on pancreatic duct cells
1) Low duodenal pH= secretin secretion
2) Secretin mainly induces duct cell secretion of bicarbonate
How does else does secretin regulate acid secretion?
1) Increased release of somatostatin from gastric D-cells
2) Decreased gastrin secretion from G-cells
3) Decrease proton pump expression by parietal cells
What are the three phases of pancreatic secretion?
What happens in the Cephalic phase of pancreatic secretion?
Vagal pathways induce pancreatic enzyme secretion in response to site, taste, smell, & mastication
What happens in the Gastric phase of pancreatic secretion?
Vagal/ Gastrin induce pancreatic enzyme secretion in response to distention, gastrin, and peptides in the stomach
What happens in the Intestinal phase of pancreatic secretion?
CCK, Secretin, & Enterpancreatic reflexes lead to pancreatic enzymes secretion in response to amino acids, fats, and H+ in the small intestine
*****Note that this is the phase the results in the majority of maximum enzyme secretion
What is the stimulus for returning the levels of pancreatic secretion from the fed state to the interdigestive state?
Once the contents of the intestines reach the ILEUM, fats in the ileum induce the release of Peptide YY & Somatostatin; these hormones return pancreatic secretions to interdigestive levels
What are the regulators of the cyclic pattern seen in the MMC?
1) Stimulation of the PNS pathways
3) Inihibition by a a-adrenergic input
What cell type secretes CCK? What is the key stimulus for this cell to release CCK?
Aside from the zymogens, what are the other pancreatic enzymes that are secreted?
Active enzymes are secreted from the pancreas in addition to the inactive proteases:
- Carboxyle ester lipase
- Trypsin inhibitor
What is pancreatitis?
Inflammation of the pancreas
What is acute pancreatitis?
Acute inflammation of the pancreas associated typically with alcoholism or obstruction of the pancreatic or common bile duct leading to:
- Autodigestion of pancreas
- Inflammatory mediators released
- Damage to other tissues
- Malabsorption of dietary nutrients
What is chronic pacreatitis?
Continued damage of the pancreas, typically from alcohol abuse
What can pancreatitis lead to?
- Malabsorption Syndrome
- Cancer i.e. adenocarcinoma of the pancreas