Pancreas Flashcards
Embryology of pancreas
Dorsal and ventral pancreatic buds- ventral bud rotates clockwise to fuse with the larger dorsal bud and create the duct of Wirsung- the main pancreatic duct
What happens if the dorsal and ventral pancreatic buds don’t fuse?
Pancreas divisum- duct of Santorini drains a part of the exocrine pancreas thru a separate minor duodenal papilla.
Aw pancreatitis
What is annular pancreas?
Ventral bud doesn’t rotate, so duod is encircled.
Can cause duodenal obstruction
Anatomic location of the pancreas
Retroperitoneal
Posterior to stomach
Anterior to IVC and Ao
4 parts- head (incl uncinate process), neck, body, tail
Transverse orientation- head is by C loop of duod, body is over spine, tail is in splenic hilum
Arterial blood supply to pancreatic head
Anterior and posterior pancreaticoduodenal arteries.
These are from the superior pancreaticoduodenal artery, which is a continuation of the gastroduodenal artery, and also from the inferior pancreaticoduodenal artery, which is from the SMA.
Arterial supply to body and tail
Branches of splenic and L gastroepiploic arteries
Where does venous drainage go to after the pancreas?
follows arterial anatomy and enters the portal circulation
What nerves are responsible for transmitting pancreatic pain?
Sympathetic nerves
Which nerves innervate islet, acini, and ductal systems?
Efferent postganglionic parasympathetic
What surgery is done for pts with intractible pain from chronic pancreatitis?
Splanchnicectomy (sympathectomy)
What are the fnl units of the endocrine pancreas?
Islets of Langerhans- multiple small glands scattered thru-out pancr, only make up 1-2% of pancreas (the rest is exocrine tsu)
What are the types of islet cells?
Alpha
Beta
Delta
F (Pancreatic Polypeptide)
What do alpha cells make? And when?
Glucagon
Secreted in response to AAs, CCK, gastrin, catecholamins, sympathetic and parasympathetic nerves
Ensures fuel during periods of fasting
What effects do alpha cells have on the liver?
Promotes hepatic gluconeogenesis and glycogenolysis
What effects do alpha cells have on the stomach?
Inhibits GI mobility and gastric acid secretion
What do beta cells make? And when?
Insulin
In response to glucose, AAs, vagal stimulation.
After meals- promotes storage of ingested nutrients
Where in the circulation is insulin released?
Into portal circulation
T/F Insulin locally inhibits alpha cells from secreting glucagon
True
What does insulin do in the liver?
Inhibits gluconeogenesis
Promotes synthesis and storage of glycogen
Prevents glycogen breakdown
What does insulin do in adipose?
increases glucose uptake by adipocytes
promotes triglyceride storage
inhibits lipolysis
What does insulin do in muscle?
promotes synthesis of glycogen and protein
What is secreted by delta cells? and when?
Somatostatin
same stimuli that promote insulin release- AAs, glucose, vagal stim
What does somatostatin do?
decreases pancreatic exocrine fn, reducing splanchnic blood flow, decreasing gastrin and gastric acid production, reducing gastric emptying time- these all slow the mvmt of nutrients from the intestine into circulation
Also has inhibitory effects on insulin, glucagon, PP secretion
What do F cells secrete? and when?
PP (pancreatic polypeptide)
after ingestion of a mixed meal
fn unknown.
Basic fnl unit of exocrine pancreas
Acinus.
Acinar cells contain zymogen granules in the apical region of the cytoplasm.
Acini are drained by a converging ductal system that terminates in the main pancreatic excretory duct.
Centroacinar cells of individual acini form origins of ducts, mixed with intercalated duct cells.
Where do exocrine pancreatic secretions come from? (which cells)?
both ductal and acinar cells.
What do ductal cells secrete?
clear, basic, isotonic soln of water and electrolytes, rich in bicarb
What controls secretion of pancreatic fluid from ductal cells?
Secretin- hormone produced in mucosal S cells of crypts of Lieberkuhn in proximal small bowel.
Presence of intraluminal acid and bile in the sml bowel stimulates secretin rls.
Secretin binds to pancreatic ductal cell receptors and makes the ductal cells secrete fluid.
Where are pancreatic digestive enz excreted from?
Made and excreted by acinar cells (after acinar cells are stimulated by secretagogues CCK and ACh
What are the pancreatic digestive enz?
Endopeptidases- trypsinogen, chymotrypsinogen, proelastase
Exopeptidases- procarboxypeptidase A and B
Amylase
Lipase
Colipase