pancreas Flashcards
- What happens in the development of the pancreas, afer the proximal duodenum rotates clockwise?
Ventral and dorsal pancreatic buds and ducts fuse
Bile and pancreatic ducts join to drain together at major papilla
- What is the uncinate process of the pancreas originated from?
- What do the ventral and dorsal ducts emerge as respectively?
Ventral bud and duct
Ventral - Main pancreatic duct at the major papilla Dorsal - Accessory pancreatic duct at the minor papilla
- Is the accessory pancreatic duct present in everyone?
- What 2 ducts join at the major papilla?
No, in most adults it has been degenerated
Main pancreatic duct common Bile duct
- What does the fact the the pancreas is a retoperitoneal structure mean?
It does not exist within the abdomen
It is behind the posterior to the peritoneum
- Which vein is formed by the joinng of the splenic vein and the superior mesenteric vein?
Portal vein
- What is MRCP used for and how does it work?
Procedure can be used to determine whether gallstones are lodged in any of the ducts surrounding the gallbladder
Uses magnetic resonance imaging to visualise the biliary and pancreatic ducts non-invasively
- What is pancreas divisum and why does it cause the patient to have recurrent episodes of pancreatitis?
Ventral bud and dorsal buds fail to fuse and so the ventral duct which usually has a large enough capacity to cope with the flow of the pancreatic juice can no longer do so
The large flow has to therefore go through a minor duct and so they get recurrent episodes of pancreatits
- What type of imaging is used when a patient is bleeding internally and how is it done?
Angiography - accessing femoral artery, put needle in and thread wire via femoral artery to aorta. Then put dye into the coeliac axis
When patients are bleeding
- How do you define Endocrine vs Exocrine secretion?
Endocrine: Secretion into the blood stream to have effect on distant target organ (Autocrine/Paracrine) - ductless glands
Exocrine: Secretion into a duct to have direct local effect
- What percentage of the pancreatic secretion is endocrine and what part of the pancreas does this?
2%
Islets of Langerhans
- What percentage of the pancreatic secretion is exocrine and what does this involve?
98%
Secretion of pancreatic juice into duodenum via MPD/sphincter of Oddi/ampulla
- Describe the structure of acini in the pancreas
- What do acini secrete into ducts?
Attached to ducts
Grape-like clusters of secretory units
Pro-enzymes
- Describe the structure of islets
Derived from branching duct system but lose contact with the ducts to become islets
Differentiate into alpha and beta cells secreting into the blood
- Are there more islets in the head or the tail of the pancreas?
Tail
- Are the islets poorly or highly vasculated?
- How much of the islets are composed of alpha, beta and gamma cells respectively?
Highly, so it has a very good blood supply
Ensures that all endocrine cells have a site for close access to a site for secretion
alpha = 15-20% beta = 60-70% gamma = 5-10%
- Compare the structures of the secretory acinar cells and the duct cells in the acini of the pancreas
Secretory acinar cells - Large with apical secretions
Duct cells - Small and pale
- Describe the components of pancreatic juice formed by the Acinar cells
- Describe the other components of pancreatic juice formed by the Duct and Centroacinar cells
Low volume, Viscous, Enzyme-rich
High volume, Watery, HCO3- rich
- What are the functions of the bicarbonate secretion in the pancreatic juice?
Neutralises acid chyme from stomach
Prevents damage to duodenal mucosa Raises pH to optimum range for pancreatic enzymes to work Washes low volume enzyme secretion out of pancreas into duodenum
- Why does HCO3- secretion stop increasing when pH goes below 3?
Bile also contains HCO3- and helps neutralise acid chyme
Brunners glands secrete alkaline fluid
- Describe how HCO3- is produced and secreted by the pancreatic duct cells
CO2 enters pancreatic duct cell from blood and catalysed by carbonic anhydrase it reacts with H20 to form H+ and HCO3-
Na+ moves down gradient via paracellular junctions and H20 follows from the blood to the lumen AE1 transporter exchanges HCO3- from duct cell into lumen with Cl- into the duct cell Na+/H+ antiporter active on the basolateral membrane and Na+ enters the cell down gradient To maintain Na+ concn. gradient in the cell, Na+/K+ATPase transports Na+ into blood and K+ into cell To maintain K+ concn. gradient in cell, K+ returns to blood via K+ channels Cl- returns to lumen via Cl- channel (CFTR) to maintain concn. gradient established by AE1 transporter
- What makes gastric venous blood alkaline and pancreatic venous blood acidic?
Stomach- H+ → Gastric Juice, HCO3- → blood
Pancreas- HCO3- secreted as pancreatic juice, H+ → blood
- Which classes of digestive enzymes are present in the Acinar cell enzyme secretion?
- Why are proteases released as inactive pro-enzymes and what are they stored in?
- what would happen if there was a blockage in MPD?
Lipases - Fat
Proteases - Protein
Amylase - Carbohydrates
Protects acini and ducts from auto-digestion, zymogen granules
may overload protection-> auto digestion
- What other protective mechanisms against auto-digestion of the pancreas are there?
Pancreas contains trypsin inhibitor to prevent trypsin activation
Enzymes only activated in the duodenum - where they have to start digesting food
- What enzyme is secreted by the duodenal mucosa and what does it do?
- What is the function of trypsin?
Enterokinase (enteropeptidase)
Converts trypsinogen → trypsin
Converts all other proteolytic and some lipolytic enzymes into their active form
