L13 - Pancreatitis & Pancreatic cancer Flashcards
Pancreatitis
Inflammatory process, pancreatic enzymes auto digest gland
Briefly state function of endocrine and exocrine pancreas?
Endocrine: Insulin production
Exocrine: Digestive enzymes
Briefly describe enzyme production and travel?
- Pancreatic acinar cell produce digestive enzymes.
- Packaged in golgi to produce zymogens
- zymogens travel to pancreatic ductal cell
- pancreatic duct
- small intestine
- brush border of duodenum
Enzymes are stimulated by the release of?
- vagal nerve
- VIP
- GRP (gastrin releasing peptide)
- secretin
- CCK
- encephalins
How is Trypsinogen converted to active form?
Enterokinase will cleave the N-hydroxyterminal hexapeptide fragment from Trypsinogen to form trypsin.
What limits further pancreatic secretion?
Elevated levels of trypsin (unbound from digested food) lead to decreased CCK and secretin levels.
How is premature activation of pancreatic enzymes limited?
- proteins translated into inactive pro enzymes
- pro-enzymes packaged in paracrystalline arrangement with protease inhibitor.
Common cause of biliary tract disease?
Gall stone in bile duct.
Getting temporarily lodged in sphincter of Oddi.
Describe how presence of alcohol may lead to blockage of pancreatic outflow?
- Ethanol lead to intracellular accumulation of digestive enzymes, premature activation & release
- Increases permeability of ductules
- enzymes reach parenchyma
- pancreatic damage - Increases protein content of pancreatic juice
- Decreases HCO3- level
- Decreases trypsin inhibitor concentration
Leads to formation of protein plugs - blocks pancreatic outflow
Describe chronic pancreatitis?
Continuing, inflammatory process of the pancreas, characterised by irreversible morphological change.
Signs / symptoms of chronic pancreatitis?
Abdominal pain.
Intermittent attacks of severe pain, often in mid abdomen or left upper abdomen.
Diarrhoea.
Weight loss.
What might be seen on a CT of a patient with chronic pancreatitis?
Inflammation, calcium deposits.
Pancreatic calcification.
Dilated duct.
Describe endoscopic retrograde cholangiopancreatography?
- Endoscopy and fluroscopy to visualise and treat problems of the biliary and pancreatic duct.
Compare and contrast acute and chronic pancreatitis?
Acute Pancreatitis
- Severe abdo pain.
- Nausea, vomitting.
- Inflamed (neutrophil and oedema)
- serum amylase and lipase HIGH
- most patients make full recovery
Chronic pancreatitis
- irreversible
- inflammation (monocyte & lymphocyte)
- leads to fibrosis and calcification
How may pancreatic fibrogenesis occur?
- (GF, cytokines, chemokines) leads to deposition of ECM & fibroblast proliferation
- Pancreatic injury: local expression and release of transforming growth factor beta
- TGF beta, stimulates growth of cells of mesenchymal origin
- Enhances synthesis of ECM proteins: collagen, fibronectin and proteoglycan
Describe alcoholic chronic pancreatitis?
- Alcohol increases acinar cell protein secretion
- Decreases fluid , HCO3- from ductal epithelial cells.
- Hence viscous fluid, results in proteinaceous debris coagulating in lumen
- Ductular obstruction
- Upstream acinar atrophy and fibrosis
Role of cytochrome P450?
Involved in formation and metabolism (breakdown) of various molecules and chemicals within cells.
Describe metabolism of alcohol?
- Alcohol dehydrogenase oxidatively metabolises alcohol first to acetylaldehyde - acetate
- If concentration of alcohol increases, cytochrome P450 2E1 induced to meet metabolic demands
Describe enzymes involved in protein synthesis?
Trypsin & Chymotrypsin - partially digested peptides to various sizes
Carboxypolypeptidase - some peptides split into amino acids
Describe basic stimuli causing pancreatic secretion
ACH
- released from parasymp vagus nerve ending and from other cholinergic nerves in enteric nervous system
CCK & secretin
- secreted by duodenal, jejunal mucosa when food enters small intestine