Liver, Gallbladder, Pancreas B&B

Question 1

what is the anatomical significance of the ampulla of Vater?

Answer 1

where biliary and pancreatic duct merge an empty into major duodenal papilla —> secretion of bile and pancreatic enzymes into duodenum

Also, represents anatomical transition from foregut (celiac trunk) to midgut (SMA)

Question 2

What is the anatomical location where the foregut, supplied by the celiac trunk, transitions to the midgut, supplied by the superior mesenteric artery?

Answer 2

Ampulla of Vater: where biliary and pancreatic duct merge an empty into major duodenal papilla —> secretion of bile and pancreatic enzymes into duodenum

Question 3

What muscle controls the flow of bile and pancreatic enzymes into the duodenum and prevents reflux?

Answer 3

Sphincter of Oddi: circular smooth muscle layer, surrounds major duodenal papilla

Question 4

describe the blood supply to the liver lobules

Answer 4

2 blood supplies: portal vein (80%, deoxygenated blood from GI tract) + hepatic artery (20%)

1 drainage vessel: hepatic veins (carry processed blood away from liver)

and then there’s a bile duct also in the triad

Question 5

what are the zones of the liver?

Answer 5

blood enters liver via portal triad (hepatic artery [20%] + portal vein [80%] + bile duct)

then enters Zone I - periportal
then Zone II - mid zone
then Zone III - centrilobular

then exits via hepatic vein

[blood flows from portal triad towards hepatic vein, bile flows away from hepatic vein towards portal triad]

Question 6

which zone of the liver is primarily affected by viral hepatitis, and why does this make sense?

Answer 6

Zone 1 – periportal

this is the zone closest to the portal triad where blood will enter from the G.I. tract (via portal vein) – viral hepatitis is transmitted via fecal-oral, so this makes sense

Question 7

which zone of the liver is most vulnerable to ischemia?

Answer 7

Zone III - centrilobular

this is furthest from the blood supply in portal triad (portal vein + hepatic artery)

fat accumulation begins here in alcoholic liver disease, and there is a high concentration of P450 enzymes in these hepatocytes

Question 8

what is the embryological origin of the pancreas?

Answer 8

formed from two buds off the endodermal lining of foregut - ventral and dorsal, which eventually fuse

ventral bud = part of head + main pancreatic duct
dorsal bud = rest of head + body + tail + accessory duct

Question 9

which abdominal organ is considered secondarily retroperitoneal?

Answer 9

Pancreas – forms covered in peritoneum (intraperitoneal) but later fuses with posterior wall to become retroperitoneal

Question 10

what is the cause of an annular pancreas?

Answer 10

Congenital anomaly of the ventral bud of the developing pancreas – fuses around the duodenum and causes bowel obstruction

Question 11

pancreatic divisum

Answer 11

dorsal and ventral pancreatic ducts do not fuse during development —> 2 separate ducts

often asymptomatic, many cause pancreatitis

accessory (dorsal) duct drains majority of pancreas, second ventral duct persists