panc Flashcards
The pancreas is a soft, elongated, flattened gland that is 12 to 20 cm in length.
The adult gland weighs between 70 and 110 g.
The pancreas is coarsely lobulated and covered with fine connective tissue, without a true capsule. It is primarily retroperitoneal, lying approximately at the level of the L1-L2 lumbar vertebrae lying
approximately at the level of the L1-L2 lumbar vertebrae.
head of the pancreas is on the right, lying within the curvature of the duodenum, and the remainder of the pancreas lies obliquely in the posterior abdomen, with the tail extending as far as the gastric surface of the spleen
The anterior surface of the head of the pancreas is adjacent to the pylorus, the first part of the duodenum, and the transverse colon.
The posterior surface abuts the hilum7 and medial border of the right kidney, the inferior vena cava and the right renal vessels, the right gonadal vein, and the right crus of the diaphragm
The uncinate process (lingula) is a prolongation of pancreatic tissue that projects off the lower part of the pancreatic head, extending upward and to the left. The uncinate process lies anterior
to the aorta and inferior vena cava and is covered superiorly by the superior mesenteric vessels that emerge below the neck of
the pancreas.
The neck of the pancreas is a constricted part of the gland, extending from the head of the pancreas toward the left to connect the head with the body of the pancreas. It is 1.5 to 2 cm long and 3 to 4 cm wide.
Posterior to the neck of the pancreas lies the confluence of the portal vein with the superior mesenteric and splenic veins.
Anteriorly it is covered in part by the pylorus
and peritoneum of the lesser sac. The neck extends to the right as far as the anterosuperior pancreaticoduodenal artery from the
gastroduodenal artery
The body of the pancreas runs toward the left side, anterior to the aorta.
It is retroperitoneal and held against the aorta by the
peritoneum of the lesser sac. The anterior surface of the body is covered by peritoneum of the omental bursa, which separates the stomach from the pancreas.
The antrum and body of the stomach and the transverse mesocolon contact the body anteriorly.
Posterior to the body of the pancreas are the aorta, the origin of the superior mesenteric artery, the left crus of the diaphragm, the left kidney, the left adrenal gland, and the splenic vein.
Posterior to the body of the pancreas are the aorta, the origin of the superior mesenteric artery, the left crus of the diaphragm, the left kidney, the left adrenal gland, and the splenic vein.
The tip of the tail is intraperitoneal lying
between layers of the splenorenal ligament. The relationship of the pancreas to important structures in the posterior abdomen is seen
The main pancreatic duct (of Wirsung) begins near the tail of the pancreas. It is formed from anastomosing ductules draining the lobules of the gland. It courses left to right and is enlarged by additional ducts.
Through the tail and body, the duct lies midway
between the superior and inferior margins and slightly posterior.
The main duct turns caudal and posterior on reaching the head of the pancreas. At the level of the major papilla, the duct turns horizontally to join in most cases with the bile duct
The duct of Wirsung and the common bile duct empty into the duodenum obliquely via the major papilla. The ampulla of Vater is the common pancreaticobiliary channel within the papilla where the 2 ducts come together, separated by common adventitia
The proximal portion of the embryonic dorsal pancreatic duct remains patent in about 70% of adults and empties through the accessory papilla
Pancreas divisum. The embryonic dorsal and ventral ducts fail to fuse.
Most of the pancreatic secretion empties through the accessory papilla. Only pancreatic secretions from the uncinate process and part of the head of the pancreas
The length of the common channel (when present)
averages 4.5 mm, with a range of 1 to 12 mm
Three circular muscle bundles, collectively called the sphincter of Oddi, act as sphincters encircling each duct as well as the ampulla of Vater.
two thirds to three quarters of the general population
has a common channel, whereas about one fifth have completely separate openings and just under 10% have an interposed sputum that separates the 2 ducts.
Long common channels or pancreaticobiliary
malunion can predispose to pancreatitis or biliary cancer
Approximately 70% of the general population has a patent accessory duct (of Santorini), which is also known as the minor duct
The accessory duct lies anterior to the bile duct and drains into the minor papilla, which lies proximal to the major papilla, but is also located in the second portion of the duodenum.
Up to 10% of people have an interruption between
the major papilla and the main duct, with drainage into the duodenum occurring via the minor papilla; this variant is called pancreas divisum
The main pancreatic duct is widest at the head of the pancreas, and the duct gradually tapers as it progresses to the tail
Upper limits of normal for the pancreatic duct diameter in the head (5 mm), body (4 mm), and tail (3 mm) are generally accepted
The pancreas has a rich circulation that is derived from branches of the celiac and superior mesenteric arteries.
The head of the pancreas and surrounding duodenum are supplied by 2 pancreaticoduodenal
arterial arcades.
They are formed by the anterior and
posterior superior pancreaticoduodenal arteries from the hepatic branch of the celiac artery that join a second pair of anterior and posterior inferior pancreaticoduodenal arteries branching from the superior mesenteric artery
The course of the splenic artery is posterior to the body and tail and loops above and below the superior margin of the pancreas.
It gives off the dorsal pancreatic artery, which usually joins one of the posterior superior arcades after giving off the inferior pancreatic artery
The caudal pancreatic artery arises from the left gastroepiploic artery or from a splenic branch at the spleen.
It joins with branches of the splenic and great pancreatic arteries and other pancreatic arteries.
It flows into the portal venous system, which is formed by the joining of the superior mesenteric and splenic veins at the confluence behind the neck of the pancreas.
The portal vein lies behind the pancreas and in front of the inferior vena cava.
The common bile duct lies anterior to the portal
vein with the hepatic artery to the left of the common bile duct.
The splenic vein originates at the hilum of the spleen and curves behind the tail of the pancreas and below the splenic artery, to the right along the posterior surface of the pancreas
The pancreatic veins drain the neck, body, and tail of the pancreas and join the splenic vein. The pancreaticoduodenal veins lie close to their corresponding arteries and empty into the splenic or portal veins.
small periacinar and perilobuar capillary
networks that drain into larger ducts alongside pancreatic
blood vessels
The superior lymphatic vessels run along the
upper border of the pancreas closely with the splenic blood vessels, whereas inferior lymphatic vessels run with the inferior pancreatic artery.
Superior and inferior lymphatic vessels draining the left pancreas, including the tail of the pancreas and left half of the body empty into nodes in the splenic hilum.
The visceral efferent innervation of the pancreas is through the vagi and the splanchnic nerves by way of the hepatic and celiac plexuses.
The efferent fibers of the vagi pass through
these plexuses without synapsing and terminate in parasympathetic ganglia found in the interlobular septa of the pancreas.
The visceral efferent innervation of the pancreas is through the vagi and the splanchnic nerves by way of the hepatic and celiac plexuses.
The bodies of the postganglionic sympathetic
neurons are in the great plexuses of the abdomen.
Their postganglionic fibers innervate only blood vessels. The autonomic fibers, both efferent and afferent, are located in proximity to the blood vessels of the pancreas. The vagi also carry some visceral afferent fibers
The basic subunit of the exocrine portion is the acinus,
which is at its base a spherical mass of dark-staining secretory cells called acinar cells
The spherical acinus connects to a goblet-shaped neck that is composed of tubular cells called
duct cells.
The inner lumen of the acinus forms the terminal portion of the secretory duct
The pancreatic ductal system is nonstriated and is lined by columnar epithelium
acinar cells are tall pyramidal or columnar
epithelial cells, with their broad bases on a basal lamina and their apices converging on a central lumen. In the resting state, numerous eosinophilic zymogen granules fill the apical portion of the cell.
The basal portion of the cells contains 1 or 2 centrally
located, spherical nuclei and basophilic cytoplasm.
The most prominent feature of the acinar cell is the dense zymogen granules that are concentrated in the apical pole.
Rough ER occupies about 20% of the cell volume
It takes up most of the basal region of the acinar cells and interdigitates with the zymogen granules in the apical region. This abundance of rough ER allows the acinar cell to synthesize more protein than any
other parenchymal cell in the body.
centroacinar cells, bridge acinar cells with the ductal epithelium.
These centroacinar cells are pale-staining on H&E staining and smaller than the acinar cells.
The collagen fibers and other extracellular matrix proteins are secreted by a less common resident cell type, the pancreatic stellate cell (PSC).
The islets of Langerhans number about 1 million in the human pancreas
There are 5 major cell types in the endocrine pancreas.
Beta cells are the most numerous, constituting about 50% to 80% of the islets. They secrete insulin and amylin.
PP cells, also known as F cells, make up 10% to 35% and secrete pancreatic polypeptide and adrenomedullin.
Alpha cells make up 5% to 20% and secrete glucagon. The remaining 5% consists of delta cells, which secrete
somatostatin, and epsilon cells, which secrete ghrelin.
Other rarer subpopulations of islets make additional hormones such as galanin.
The pancreas arises from posterior foregut endoderm
Two buds form: 1 dorsal and 1 bi-lobed ventral bud.
About a month into gestation, the foregut evaginates into a condensation of overlying mesenchyme to form the first morphologic evidence of the dorsal bud.
About a week later, a ventral bud forms as an outpouching of hepatic diverticulum. The ventral bud has a bilobed origin, of which the left ventral bud gradually regresses.
Both dorsal and ventral buds undergo elongation of a stalk region and branched morphogenesis
At 37 to 42 days into gestation, as the duodenum grows, the ventral pancreas rotates around the duodenum and fuses with the dorsal pancreas
The dorsal pancreas forms the tail, body, and superior portion of the pancreatic head. It also contains the dorsal duct that forms the distal portion of the main pancreatic duct (of Wirsung) and the entire minor accessory duct (of Santorini).
The ventral pancreas forms the uncinate process and the inferior part of the head.
The ventral pancreas’s ventral duct forms the proximal portion of the main pancreatic duct (of Wirsung).
As mentioned earlier, the 2 duct systems corresponding to the ventral and dorsal buds fail to fuse in up to 10% of the general population
pancreas divisum, the accessory duct functions as the main conduit for drainage of pancreatic juice
The clinical significance of pancreas divisum is discussed later. Failure of the ventral pancreas to fully rotate around the duodenum, or persistence of the left ventral bud can lead to an annular pancreas, also discussed later
Failure of the ventral pancreas
to fully rotate around the duodenum, or persistence of the left ventral bud can lead to an annular pancreas
After the pancreatic buds fuse, the cellular architecture of the pancreas rapidly expands.
Notably, all 3 functionally distinct parenchymal cell types—acinar, duct, and islet cells—differentiate
from a common pancreatic progenitor lineage.
The first, termed the primary transition,
is defined as the conversion of predifferentiated cells to a protodifferentiated state in which low levels of pancreas-specific proteins are present.
The second phase, or the secondary transition,
is marked by a dramatic rise in pancreatic cell number and pancreas- specific protein synthesis, as well as an acceleration in both exocrine and endocrine differentiation
Annular pancreas is a congenital anomaly in which a portion of the pancreas forms a thin band around the preampullary portion of the duodenum, leading to complete or partial bowel obstruction
Although annular pancreas is often diagnosed prenatally or during infancy, it is erroneous to consider it solely a disease of infancy.
A second peak of detection occurs in the fourth through seventh decades of life
Pancreas divisum (PD) results from a failure of the dorsal and ventralpancreatic ducts to fuse during embryogenesis resulting in the majority of exocrine secretions draining from the relatively smaller dorsal duct of Santorini and minor papilla
3 types of pancreas divisum identified
Classic or complete divisum, in which there is complete failure of fusion between the dorsal duct (Santorini) and ventral duct (Wirsung), occurs in 71% of patients with PD.
The second type of PD called dominant type or dorsal duct pancreas divisum, in which there is absence of the ventral duct, occurs in 6% of patients with divisum
The last type, incomplete pancreas divisum, in which there remains a small communication between the ventral and dorsal ducts, occurs in 23% of patients
Ectopic (heterotopic) pancreatic tissue, often referred to as a pancreatic rest
Pancreaticobiliary malunion (PBM) is a congenital malformation in which a common channel for bile and pancreatic fluid is formed, owing to the absence of a septum between the ducts
The abnormal union occurs outside the duodenal wall; thus the influence of the sphincter of Oddi is lost, allowing reflux of pancreatic exocrine secretions into the biliary system, and bile into the pancreatic duct.
markedly elevated amylase concentration can be detected in the bile of patients with a common channel of 5 mm or greater
Biliary neoplasms are most frequently
seen in the gallbladder;
however, bile duct neoplasms can also occur with increased risk in presence of congenital biliary dilation, 32.1%, versus 7.3% in patients without biliary dilation
A classification for PBM has been proposed by dividing it into 3 types:
a pb type, in which the pancreatic duct appears to join
the bile duct;
a bp type, in which the insertion of the bile duct is into the pancreatic duct
a Y type, in which there is a long common channel measuring greater than 15 mm in length
In large series, the bp and pb types have each been reported to be the most common type of PBM
Pancreaticobiliary malunion is diagnosed by traditional cholangiography (ERCP, intraoperative cholangiography, or percutaneous cholangiography), MRCP, or helical CT scan. Traditional cholangiography remains the gold standard
The functional unit of the exocrine pancreas is composed of anacinus and its draining ductule
The ductal epithelium extends to the lumen of the acinus, with the centroacinar cell situated as an extension of the ductal epithelium into the acinus
The centroacinar cell plays a key role in providing
progenitor cells for pancreatic cell lineages
The ductule drains into interlobular (intercalated) ducts, which in turn drain into the main pancreatic ductal system.
The duct epithelium consists of cells that are cuboidal to pyramidal and contain the abundant mitochondria necessary for energy products needed for ion transport
The duct cells as well as the centroacinar cells contain carbonic anhydrase, which is important for their ability to secrete bicarbonate
The purposes of the water and ion secretions are
to deliver digestive enzymes to the intestinal lumen and to help neutralize gastric acid emptied into the duodenum
Pancreatic juice secreted during stimulation with secretin is clear, colorless, alkaline, and isotonic with plasma.
The flow rate increases from an average rate of 0.2 or 0.3 mL/min in the resting (interdigestive) state to 4.0 mL/min during postprandial stimulation.
The total daily volume of secretion is 2.5 L
pancreas is stimulated by secretin (the major mediator of the greater volume output), bicarbonate and chloride concentrations change reciprocally
Secretin stimulates secretion by binding to its receptor on the basolateral membrane of the duct cell, thus activating adenylate cyclase and increasing cyclic adenosine monophosphate (cAMP);
acetylcholine does so by binding to its receptor and
raising intracellular calcium concentrations.
Human amylase is secreted by both the pancreas and salivary
glands. These enzymes digest starch and glycogen in the diet.
Salivary amylase initiates
digestion in the mouth and may account for a significant portion of starch and glycogen digestion because it is transported with the meal into the stomach and small intestine, where it continues to have activity.
In the stomach, the amylase activity is protected from secreted gastric acid by buffering from the meal and by the
protected alkaline environment of salivary and gastric mucus.
The pancreas secretes 3 lipases: lipase (or TG lipase), prophospholipase A2, and carboxylesterase
Salivary (lingual) and gastric lipases also contribute to fat digestion but in a minor fashion
Pancreatic lipase binds to the oil-water interface of the TG oil droplet, where it acts to hydrolyze a TG molecule to 2 fatty
acid molecules released from carbons 1 and 3 and a monoglyceride with a fatty acid esterified to glycerol at carbon
Bile acids aid in the emulsification of TG to enlarge the surface area for lipase to act on, and they form micelles with fatty acids and monoglycerides, which in turn remove these products from the oil-water interface.
Colipase is believed to form a complex with lipase and bile salts. This ternary complex anchors lipase and allows it to act in a more hydrophilic environment
on the hydrophobic surface of the oil droplet.
Phospholipase A2 catalyzes the hydrolysis of the fatty acid ester linkage at carbon 2 of phosphatidylcholine.
This cleavage leads to the formation of free fatty acid and lysophosphatidylcholine
The pancreas secretes a variety of proenzyme proteases that are activated in the duodenum by trypsin
Trypsin, chymotrypsin, and elastase are endopeptidases that cleave specific
peptide bonds adjacent to specific amino acids
carboxypeptidases, which are
exopeptidases that cleave peptide bonds at the carboxyl terminus of proteins
The combined actions of gastric pepsin and the pancreatic proteases result in the formation of oligopeptides and free amino
acids. The oligopeptides can be further digested by enterocyte brush-border enzymes
These amino acids have greater effects on stimulating pancreatic secretion, inhibiting gastric emptying, regulating small bowel motility, and causing satiety.
The vagal nerves mediate the cephalic phase of the exocrine secretion.
Acetylcholine is certainly a major neurotransmitter involved in mediating cephalic phase pancreatic secretion because cholinergic antagonists greatly reduce and in some cases abolish sham
feeding–stimulated pancreatic secretion in humans
Nerve endings containing the peptides VIP, GRP, CCK, and enkephalins have been identified in the pancreas
gastric phase of pancreatic secretion results from meal stimuli acting in the stomach.
The major stimulus is gastric distention,
which causes predominantly secretion of enzymes with little secretion of water and bicarbonate
Three gastric processes—secretion of acid, pepsin, and lipase; digestion; and emptying—are tightly coupled
to the mechanisms of the intestinal phase of pancreatic secretion
The intestinal phase begins when chyme first enters the small intestine from the stomach
It is mediated by hormones and
enteropancreatic vagovagal reflexes.
Secretin is released from enteroendocrine
S cells in the duodenal mucosa when the pH of the lumen is less than 4.5
The most potent amino acids for stimulating pancreatic secretion in humans are phenylalanine, valine, methionine, and tryptophan.
Truncal vagotomy and atropine markedly inhibit the enzyme (and bicarbonate)
responses to low intestinal loads of amino acids and fatty acids, as well as to infusion of physiologic concentrations of CCK.
These results indicate that vagovagal reflexes mediate enzyme secretion and augment bicarbonate secretion stimulated by secretin.
CCK is the major humoral mediator of meal-stimulated enzyme secretion during the intestinal phase. The circulating
concentration of CCK rises with a meal
Pancreatic Secretory Function Tests
Secretin Measurements of volume and
HCO3– secretion into the
duodenum after IV secretin
Provide the most sensitive and specific
measurements of exocrine pancreatic
function
Require duodenal intubation and IV administration of hormones; not widely available
Detection of mild, moderate, or severe exocrine pancreatic dysfunction
CCK
Measurements of duodenal outputs of amylase, trypsin, chymotrypsin, and/or lipase after IV CCK
Secretin and CCK
Measurements of volume,
HCO3 −, and enzymes after IV secretin and CCK
Indirect (Requiring Duodenal Intubation)
Lundh test meal Measurement of duodenal
trypsin concentration after oral ingestion of a test meal
Does not require IV administration of
hormones
Indirect (Tubeless)
Fecal fat Measurement of fat in the stool
after ingesting meals with a known amount of fat
Provides a quantitative measurement of
steatorrhea
Fecal Elastase 1
NBT-PABA
Oral ingestion of NBT-PABA or fluorescein dilaurate with a meal, followed by
measurements of PABA or
fluorescein in serum or urine
The most common known causes of Acute Pancreatitis in children are biliary tract disease (10% to 30%), medications (25%), systemic disease (33%), trauma
(10% to 40%), metabolic disease (2% to 7%), and HP (5% to
8%); 13% to 34% of cases are idiopathic
Pancreas divisum is the most common anatomic aberration, although a wide variety of other structural abnormalities of
the bile and pancreatic duct also have been observed
AP is the most common pancreatic disease,
whereas pancreatic cancer is the most lethal
This increase is presumably—as in adults—due to the rise in obesity-associated cholelithiasis.
2012 Atlanta Classification Revision of Acute Pancreatitis
MILD ACUTE PANCREATITIS
No organ failure
No local or systemic complications
MODERATELY SEVERE ACUTE PANCREATITIS
Transient organ failure (<48 hr) and/or
Local or systemic complications* without persistent organ failure
SEVERE ACUTE PANCREATITIS
Persistent organ failure (>48 hr) single organ or multiorgan
*Local complications are peripancreatic fluid collections, pancreatic necrosis and peripancreatic necrosis (sterile or infected), pseudocyst, and walled- off necrosis (sterile or infected).
AP is now defined by a patient meeting 2 of the following 3 criteria:
(1) symptoms (e.g., acute onset epigastric and/or left upper quadrant pain, often radiating to the back) consistent with pancreatitis
(2) a serum amylase or lipase level greater than 3 times the uppe limit of the laboratory’s reference range, and
(3) radiologic imaging consistent with pancreatitis, usually using CT or MRI
Pancreatitis is classified as acute unless there are findings on CT, MRI, EUS, or ERCP suggestive of chronic pancreatitis.
If such findings are present, pancreatitis is classified as chronic pancreatitis, and any further episode of AP is considered an exacerbation of chronic pancreatitis
Mild AP, the most common form, has no associated organ failure, no local or systemic complications, and usually resolves in the first week.
Moderately severe AP is defined by the presence of transient organ failure (lasting <48 hours) and/or local complications.
Severe AP is defined by persistent organ failure (lasting >48 hours).
Local complications include acute peripancreatic fluid collections,
acute necrotic collections (pancreatic and peripancreatic necrosis, sterile or infected), pseudocyst, and walled-off necrosis
(WON; sterile or infected
Markers of severe pancreatitis include 3 or more of Ranson’s 11 criteria for non-gallstone pancreatitis and an
Acute Physiology and Chronic Health Evaluation (APACHE-II) score above 8
hemorrhagic pancreatitis is not a synonym for necrotizing pancreatitis.
When occurring early in the course, bleeding may be due to venous bleeding from the severe inflammatory process
severe, hemorrhage is more commonly associated with pseudoaneurysm formation leading to hemorrhagic collections or hemoperitoneum.
Interstitial pancreatitis accounts for nearly
75% to 80% of the cases and, on contrast-enhanced CT scan in such patients, the pancreas is perfused well, without any nonperfused, low attenuation areas.
Necrotizing pancreatitis according to the revised Atlanta classification includes both pancreatic and/or peripancreatic necrosis.
Pancreatic necrosis is diagnosed on CT scan when ≥30% of the pancreatic parenchyma is low-attenuating or nonenhancing.
Acute peripancreatic fluid collections are seen as low attenuation areas around the pancreas.
If these collections cross the fascial
planes like Gerota fascia, then one should consider them as acute peripancreatic necrotic collections rather than simple fluid collections.
Approximately 30% to 50% of cases of AP, mainly the interstitial type, have peripancreatic fluid collections, which
typically resolve.
After a period of approximately 4 weeks, if the acute peripancreatic fluid collections persist and develop a wall, then they are called a “pseudocyst.”
Pseudocysts are located adjacent to or off the body of the pancreas
Necrotic collections, which may also be peripancreatic, develop a wall after 4 weeks and are then referred to as WON
WON is pancreatic necrosis that has liquefied after 5 to 6 weeks
Similar to a pseudocyst, a wall develops. However, whereas a pseudocyst always contains fluid, pancreatic necrosis, even if walled off early, contains a
significant amount of debris that only becomes liquefied after 5 to 6 weeks.
Draining WON too early (before 4 weeks) is discouraged because the debris is typically thick, often with the consistency of rubber, early in the course of the disease.
After 4 weeks, WON can be treated similarly to a pseudocyst and drained surgically, endoscopically, or percutaneously
Most organ failure observed in the first week is also present on day 1, and at that time, one should consider (and treat) the patient as having severe AP.
If the organ failure persists beyond 48 hours, severe AP is confirmed.
If organ failure resolves within 48 hours and local complications evolve, the case would be classified as moderately severe AP
If no local complications are seen, the revised Atlanta classification still classifies the patient as moderately severe pancreatitis; however, the original description of moderately severe AP described patients with local complications but without organ failure
The second phase usually starts after 7 days and is mainly characterized by the local complications and ensuing infection of such local complications. The organ failure seen in the first phase may continue and contribute to late morbidity and mortality, usually with infected necrosis
Organ failure occurs in ∼5% of interstitial pancreatitis
Factors Associated With Severe Acute Pancreatitis
PATIENT CHARACTERISTICS
Age >55 yr
Obesity (BMI >30 kg/m2)
Altered mental status
Comorbid disease
Systemic inflammatory response syndrome (SIRS)
Two or more of the following (SIRS criteria)
Pulse >90/min
Respirations >20/min or PaCO2 <32 mm Hg
Temperature >38°C or <36°C
WBC count >12,000 or <4000/mm3 or >10% band forms
LABORATORY FINDINGS
BUN >20 mg/dL or rising BUN level
Elevated serum creatinine level
Hematocrit >44% or rising hematocrit
IMAGING FINDINGS
Pleural effusion(s)
Pulmonary infiltrate(s)
Multiple or extensive extrapancreatic fluid collections
Approximately 75% to 80%, of patients with AP have a resolution of the disease process (interstitial pancreatitis) and do not enter a second phase.
However, in ∼20% of patients, a more protracted
course develops, typically related to the necrotizing process (necrotizing pancreatitis) lasting weeks to months.
There are 2 time peaks for mortality in AP. Most studies in the USA and Europe reveal that about half the deaths occur within the first week or 2, usually from multiorgan failure
The initial step in the pathogenesis of AP is conversion of trypsinogen to trypsin within acinar cells in sufficient quantities to overwhelm normal mechanisms to remove active trypsin
Trypsin, in turn, catalyzes conversion of proenzymes,
including trypsinogen and inactive precursors of elastase, phospholipase A2 (PLA2), and carboxypeptidase, to active enzymes
Thus, complete inhibition of cathepsin B may prevent or become a treatment for AP
Factors that may initiate gallstone pancreatitis include reflux of bile into the PD or obstruction of the PD at the ampulla from stone(s) or from edema resulting from the passage of a stone
Reflux of bile into the PD could occur when the distal bile and PDs form a common channel and a gallstone becomes impacted in the duodenal papilla.
ARDS may be induced by active phospholipase A (lecithinase), which digests lecithin, a major component of lung surfactant
The pathogenesis of hypocalcemia is multifactorial
and includes hypoalbuminemia (the most important
cause), hypomagnesemia, calcium-soap formation, hormonal imbalances binding of calcium by free fatty acid–albumin complexes, intracellular translocation of calcium, and systemic exposure to endotoxin