Exocrine Pancreas Flashcards
What are the main 2 structures that make up the pancreas?
- EXOCRINE - 80-85% of pancreas made up of acinar cells forming acini
- ENDOCRINE - Islets of Langerhans
What is the normal gross structure of the pancreas? Why is it difficult to observe on necropsy?
right lobe follows the descending duodenum and the left lobe lies near the stomach
quick autolysis due to the digestive enzymes it contains
Normal pancreas histology:
cell nuclei at basal ends with cytoplasm in the middle with pink zymogen granules present when the animal is well-nourished
Exocrine pancreas acinus:
Normal pancreas, histology, dog
What is unique about the feline pancreatic duct?
fuses with the common bile duct before entering the major duodenal papilla, predisposing cats to triaditis (cholangitis, pancreatitis, IBD)
- only 20% of cats have an accessory pancreatic duct
Major duodenal papilla:
where pancreatic duct and bile duct secrete into the duodenum
What is this?
pacinian corpuscles, mechanoreceptors, commonly found on the feline pancreas (not pathological!)
Pacinian corpuscle:
- commonly found in feline pancreas
- fingerprint-like
- mechanoreceptors
What are the main 3 functions of the pancreas?
- digestion - forms “pancreatic juice”
- defense against autodigestion - produces α1-antitrypsin
- zinc homeostasis
What 4 types of enzymes secreted by the pancreas aid in digestion?
- lipase and phospholipase - dietary lipids
- trypsin and chymotrypsin - proteins
- amylase - carbohydrates
- intrinsic factor - cobalamin (vitamin B12) absorption
Why is the pancreas highly vulnerable to toxicity?
takes a major part in zinc homeostasis
What controls enzyme secretion of the pancreas?
diet
- high protein diet —> acinar cell hypertrophy or hyperplasia
- low protein diet —> acinar atrophy
Exocrine pancreas atrophy, pig:
- decreased zymogen and acini structure
- caused by starvation
What is the pathogenesis of pancreatic necrosis (pancreatitis)?
pancreatic injury leads to the release of pancreatic enzymes, especially trypsin, into the surrounding parenchyma, which further activates enzymes and causes autodigestion of the pancreatic tissue —> necrosis and pancreatitis —-> inflammation
What are the 3 major causes of pancreatitis (necrosis)?
- obstruction
- direct injury to acinar cells
- disturbances of enzyme trafficking within the cytoplasm of acinar cells
What are 4 major predisposing factors to pancreatitis (necrosis) in dogs? What breeds have a genetic predisposition?
- middle-aged to older dogs
- obesity
- high-fat diet making the pancreas work harder to produce more enzymes for digestion of lipids
- drugs that damage acinar cells
Miniature Schnauzers, Miniature Poodles, Yorkshire Terriers
What 3 underlying diseases may cause pancreatitis?
- hyperadrenocorticism
- hypothyroidism —> hypercholestreolemia
- hypertriglyceridemia —> fat mobilization
What 4 lesions are commonly seen in pancreatitis?
- fat necrosis (saponification) caused by leakage of enzymes that cause necrosis to the fat surrounding the pancreas
- necrosis of blood vessels, leading to thrombosis and hemorrhage
- inflammation
- fibrosis
What happens when ~90% of pancreatic tissue is lost in dogs due to pancreatitis?
exocrine pancreatic insufficiency +/- endocrine pancreatic insufficiency/DM (Islets of Langerhans lost/destroyed with tissue)
What are the systematic effects of acute pancreatitis due to? What 4 signs are seen?
secondary to the release of inflammatory mediators and activated enzymes from the damaged pancreas
- GI signs - vomiting, diarrhea, anorexia
- hemorrhage, shock, DIC - enzymes released into circulation
- systemic inflammation
- organ failure
Systemic effects of pancreatitis:
How does acute pancreatitis look grossly?
- edema
- diffuse hemorrhage on pallor tissue of pancreas
How does chronic pancreatitis look grossly?
gritty, chalky material on pancreas —> fat necrosis (saponification)
What plays a key role in the inflammatory response of acute pancreatitis? What drug was produced to help manage this?
neutrophils and macrophages
fuzapladib sodium monohydrate - leukocyte function-associated activation (LFA-1) inhibitor that blocks neutrophil extravasation to block excessive inflammation that exacerbates pancreatitis
What are the main sources of zinc that cause toxicosis? What are the most common clinical signs?
alloys, galvanized products (penny), pesticides, herbicides
- vomiting, diarrhea
- icterus, anemia
- tachycardia
- hemoglobinuria, hemoglobinemia
- acute kidney and/or liver failure, pancreatitis, DIC
How does the histopathology of zinc toxicosis appear?
acute acinar cell necrosis —> basilar vacuole degeneration in acini lacking zymogen
Gastric foreign body, zinc toxicosis:
digestion of penny in GI tract exposes zinc under the copper galvanization
GIT foreign body, bird:
metal - zinc toxicosis
GIT foreign body, bird, secondary zinc toxicity:
What dog breeds are predisposed to exocrine pancreatic atrophy (juvenile pancreatic atrophy)? What are the most common clinical signs?
German Shepherds** and Rough-Coated Collies
- maldigestion, diarrhea
- malodorus feces
- weight loss with polyphagia (due to inability to digest food)
- poor coat
How does exocrine pancreatic atrophy (juvenile pancreatic atrophy) look grossly?
atrophied pancreas that is poorly demarcated and looks see-through
In what species is it common to find nodular hyperplasia of the pancreas?
dogs, cats, cattle - no clinical significance
- may look like a carcinoma
- nodules lacking necrosis or hemorrhage - no reaction = no clinical significance
- check Hx for pancreatitis/neoplasia if unsure
What are 2 common sequels to adenocarcinomas of the pancreas?
- extension to peritoneum or duodenum by carcinomatosis - seeded through peritoneal cavity
- metastasis to lymph nodes, liver, or lungs (through vessels)
Pancreatic carcioma, dog:
- lobulated pancreas with huge nodule effacing other lobe
- infiltrative
Pancreatic adenocarcinoma, peritoneal carcinomatosis:
- tiny, numerous nodules on omentum and serosa of organs
- uncurable, affects multiple organs
Hepatic carcinoma, peritoneal carcinomatosis:
What paraneoplastic syndrome is commonly seen with pancreatic neoplasia? How does it present?
feline alopecia, usually associated with pancreatic carcinoma or cholangiocarcinoma
ventral truncal alopecia with a shiny appearance to the skin due to follicular atrophy
Feline paraneoplastic alopecia:
- well-demarcated, lobulated, firm white mass
- at the extremity of the left pancreatic lobe with an enlarged pancreatic lymph node
- pancreatic carcinoma
