Exam 5: Exocrine Pancreas Flashcards
What does the bile duct enter in dogs?
Major duodenal papilla
What is the most important duct in dogs?
Accessory pancreatic duct
Where does the accessory pancreatic duct enter in dogs?
Minor duodenal papilla separate from bile duct
Describe the pancreatic duct in dogs
Less important
May not be present
Empties into major duodenal papilla separate from bile duct
What is the most important duct in cats?
Pancreatic duct
What does the pancreatic duct enter in cats?
Major duodenal papilla after joining with the common bile duct first
Describe the accessory pancreatic duct in cats
Only present in 20% of cats
What are the functions of the exocrine pancreas?
Release of inactive digestive enzymes
Neutralization of gastric acid
Secretion of intrinsic factor
What is intrinsic factor secreted by in humans?
Parietal cells
What does intrinsic factor do?
Facilitates B12 absorption in the distal small intestine
What happens from a lack of B12?
Pernicious anemia in people
Diarrhea in dogs and cats
What does bicarbonate do?
Neutralizes gastric acid
What does the neutralization of gastric acid by bicarb do?
Intestinal mucosa protection
What is necessary for enzyme activity?
Increased pH
What is bicarb released by?
Ductal cells
What pancreatic safeguards protect from auto-digestion?
Zymogen synthesis (proteases)
Segregation into vacuoles in acinar cell
Trypsin inhibitors in cytoplasm
Sphincter at pancreatic duct
What does the sphincter at pancreatic duct do?
Inhibits reflux
What are the inactive zymogens?
Prozymes:
Trypsinogen and chymotrypsinogen
What is required for zymogen?
Activation
What is zymogen synthesized by?
Ribosomes
Where does the formation and storage of zymogen occur?
In vesicles (“granules”)
Describe the process that leads to zymogen secretion
Stimulation of cell
Fusion of granules to plasma membrane
Release of content into glandular lumen
Secretion into duodenum
Where does zymogen activation occue?
In duodenum
Describe enterokinase
Brush border enzyme
Activates trypsinogen into trypsin
What does trypsin activate?
Trypsinogen and chymotrypsinogen
What do trypsin inhibitors do?
Prevent activation or trypsin
Where are trypsin inhibitors formed and stored?
In acinar cytoplasm
What are trypsin inhibitors secreted by?
Acinar cells
What is an examples of a trypsin inhibitor?
α-2 macroglobulin
Describe α-2 macroglobulin
Synthesized in liver
Helps remove proteases from plasma
Describe the cephalic phase of pancreatic secretion
Minor: 20%
Smelling, tasting, chewing
Describe the gastric phase of pancreatic secretion
When food enters the stomach
Gastric distention
Describe the intestinal phase of pancreatic secretion
Most important phase
Begins when food hits the small intestine
What is the regulation of the cephalic phase of pancreatic secretion?
Neuronal
Describe the process of pancreatic fluid and bicarb secretion in the cephalic phase of pancreatic secretion
Vagus nerve stimulates the parietal cell to secrete H+
Duodenal secretin release
Pancreatic fluid and bicarb secretion
Describe the process of secretin secretion in the cephalic phase of pancreatic secretion
Vagus nerve stimulates gastrin release from antral G cells
Stimulates pancreatic enzyme secretion and parietal cells to secrete H+
Secretin secretion
What can be the result of a dog smelling food if it has pancreatitis due to the cephalic phase?
It may be painful
