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
T/F all peptidases are secreted into the ductal system as inactive precursors
True.
First trypsinogen is converted to active trypsin, and then trypsin converts everything else.
Note: amylase and lipase are excreted into the ductal system in their active forms (different from peptidases)
What converts trypsinogen to trypsin?
Duodenal mucosal enterokinase
Etiologies of acute pancreatits
alcoholism
gallstone dz
Pathogenesis of acute pancreatitis
Unclear, but maybe:
obstruction of the ampulla of vater by gallstones, spasm, or edema causes the intraductal prs to rise and bile to reflux into the pancreatic duct.
Activation of intraparenchymal enz causes tsu destruction and ischemic necrosis of the pancreas and of retroperitoneal tsus
T/F acute pancreatitis has a variable presentation
True
can vary from mild parenchymal edema to life-threatening hemorrhagic pancreatitis
HPE of acute pancreatitis
Hx of prior pancreatitis, alcoholism, biliary colic
Upper abd pain radiating to back
Naus/vom, low fever, tachycardia
Severe attack- hypotension, sepsis, multiorgan failure
If from alcohol, will be 12-48 hrs after alcohol ingestion
Upper abd tenderness but no peritoneal signs
Slightly distended abd dt paralytic ileus
DD for acute pancreatits
perforated peptic ulcer acute biliary tract dz acute intestinal obstruction acute mesenteric thrombosis leaking AAA
T/F An elevated serum amylase level is specific for acute pancreatitis
False, can also have elevated level in intestinal obstruction or perforated peptic ulcer
However, lipase is solely of pancreatic origin, so if amylase is high and it’s unclear, measure lipase.
Blood work findings in acute pancreatitis
Elevated amylase, lipase
Leukocytosis >10k
Hemoconcentration w azotemia (high nitrogen levels)
Hyperglycemia (dt hypoinsulinemia)
Hypocalcemia (dt Ca2+ deposition in areas of fat necrosis)
Dx Eval in acute pancreatitis: XR
CXR- left pleural effusion (sympathetic effusion) secondary to peripancreatic inflam; air under diaphragm indicates perf of hollow viscus, eg perf’d peptic ulcer
Abd XR- sentinel loop of dilated duod or jej located in LUQ, next to inflamed pancreas
If gallstone pancreatitis, will also see gallstones in RUQ
What is the imaging of choice for the GB and biliary system?
US
study of choice for detection of choledocholithiasis in gallstone pancreatitis
Imaging of choice for acute pancreatitis
CT- all pts show evidence of either parenchymal or peri-pancreatic inflam.
CT is also good for showing pancreatic necrosis, pseudocyst
Besides US and CT, what other modality is useful for dx eval of acute pancreatitis?
ERCP- in cases of gallstone pancreatitis, can see and extract stones in the CBD.
Also MRcholangiopancreatography is diagnostic but not therapeutic
What is used to predict severity of disease in acute pancreatitis?
Ranson criteria. # of criteria present at admission and during first 48 hrs shows mortality. Criteria at admission: age >55 wbc >16k serum glucose >200 serum LDH >150 SGOT >250
What kinds of infections can cause acute pancreatitis?
mycoplasma
mumps
Coxsackie
also ascaris (bc it can cause obstruction of pancreatic duct)
T/F Most cases of acute pancreatitis will eventually need surgery.
False. Most cases are self-limited and resolve spontaneously.
Rx for acute pancreatitis
Supportive care, Rx for complications as they arise
Hydration, NPO, Abx, O2 therapy
Why is hydration important in treating acute pancreatitis?
bc third spacing occurs secondary to parenchymal and retroperitoneal inflam.
If there is hypovolemia, pancreatic ischemia can quickly develop dt inadequate splanchnic blood flow
Why are pts with acute pancreatitis given NPO?
To decrease pancreatic stimulation.
If NPO for a long period, give IV nutirition.
Afterwards, start oral intake w low-fat, high carb liquids to avoid pancreatic stimulation.
Why is oxygen therapy needed in treating acute pancreatitis?
Hypoxia often occurs secondary to pulmonary changes (probably d/t circulating mediators)
Look for atelectasis, pleural effusion, pulmonary edema, ARDS on CXR.
How can you detect pancreatic necrosis?
CT with contrast
Non-enhancement of 50% or more of the pancreas is a strong predictor for infectious complications.
How are infected pancreatic collections treated?
Surgical debridement and drainage (to avoid sepsis)
What is a pancreatic pseudocyst?
peripancreatic collections that persist after inflammatory phase and develop and thickened wall.
Rx for pancreatic pseudocyst
Surgical drainage for cysts >6cm diameter
Internal drainage into stomach, duod, sml intestine
How do pancreatic abscesses form?
Ischemic pancreatic parenchyma progresses to necrosis; it is seeded by bacteria, and then an abscess forms.
Bacteria is usually enteric.
Rx for pancreatic abscess
Abx don’t work- need to drain it completely. And debridement too.
Percutaneous drainage usu not good enough, bc only fluid is removed but necrotic tsu still stays.
Why can hemorrhage occur in acute pancreatitis?
Secondary to erosion of blood vessels by activated proteases.
Life threatening.
Usu main hepatic, gastroduodenal, or splenic artery.
Do angiography, if that can’t stop bleeding, do surgery.
What is chronic pancreatitis
Sml number of acute pancreatitis progresses to chronic- persistent inflam that causes destructive fibrosis of the gland.
Recurring/persistent upper abd pain w evidence of malabs, steatorrhea, DM
What are the two forms of chronic pancreatitis?
calcific pancreatitis- usu a/w alcohol abuse
obstructive pancreatitis- secondary to pancreatic duct obstruction
What is calcific pancreatitis?
ductal plugging and occlusion by protein and mineral precipitates–> resulting inflam and fibrosis leads to parenchymal destruction and eventual atrophy of the gland.
usu alcohol-induced.
What is chronic obstructive pancreatitis
Ductal blockage secondary to scarring from acute pancreatitis or trauma, papillary stenosis, pseudocyst, or tumor.
Blockage results in upstream duct dilatation and inflam.
HPE for chronic pancreatitis
Abd pain (upper abd, radiating to back)- can be intermittent or persistent. Pts often addicted to narcotic pain relievers Can see sx of exocrine insufficiency- malabsorption and of endocrine insufficiency- DM
Dx eval for chronic pancreatitis
ERCP is most useful, but US and CT also used.
Need to show pathologic changes over time.
see inflammed, atrophied gland, dilated and strictured pancreatic duct, presence of caliculi- ERCP best shows these
Rx for chronic pancreatitis
Control abd pain- opiates good but addictive long term
Rx for pancreatic insufficiency is oral pancreatic enz
Insulin used to treat DM
Pt must stop using alcohol.
Surg only if med therapy fails.
Drain pancreatic duct and resect diseased tsu.
What surgery is needed for “chain of lakes”-appearing pancreatic duct?
longitudinal pancreatico-jejun-ostomy (Puestow procedure)- Roux-en-Y segment of prox jej is anastomosed side-to-side w opened pancreatic duct, so drainage can occur.
chain of lakes is dt sequential ductal scarring and dilation.
What is the Rx for distal pancreatic duct obstruction?
Distal pancreatectomy
What is the most common type of pancreatic cancer?
Ductal adenocarcinoma (80%), usu in pancreatic head.
Where mets from pancreatic cancer go?
Regional lymph nodes and liver
Also, local spread to nearby structures occurs early.
HPE for pancreatic ca
obstructive jaundice weight loss constant deep abd pain (dt peri-pancr tumor infiltration) Courvoisier's sign pruritis (w jaundice)
What is Courvoisier’s sign
Jaundice plus non-tender palpable GB- indicates tumor obstruction of the distal bile duct.
DD for malignant obstructive jaundice
carcinoma of ampulla of vater
carcinoma of pancr head
carcinoma of distal CBD
duodenal carcinoma
Dx eval for pancr ca
elevated alk phos and direct bilirubin (these mean obstructive jaundice)
CT- location, extent of invasion, mets, degree of ductal dilation
ERCP- shows ductal anatomy, can get biopsy, stent placement
T/F the average bilirubin level in bile duct obstruction from GB dz is higher than the level in neoplastic obstruction
False.
Bilirubin level is higher with neoplastic obstruction- that’s why you can use it (plus alk phos) to know that there is obstructive jaundice
What factors suggest that a pancreatic tumor cannot be resected?
local extension contiguous organ invasion SMV or portal vein invasion ascites distant mets
Rx for resectable pancreatic tumors
Whipple- pancreaticoduodenectomy
En bloc resection of antrum of stomach, duod, prox jej, head of pancr, GB, and distal CBD
T/F tumors of pancreatic body and tail are fatal
True- dx is made at a more advanced stage.
but all pancr ca has a very poor pgx, even with whipple
