CMED Gastroenterology -- Final Exam Questions with Correct Answers
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Gastroenterology
Describe the flow of bile through the liver, gall bladder, and pancreas - Answer-bile is produced in the liver and is sent out via the left or right hepatic ducts which join to form the common hepatic duct
bile in the common hepatic duct can be sent to the gallbladder for storage, or be sent dir...
CMED Gastroenterology -- Final Exam
Questions with Correct Answers
Describe the flow of bile through the liver, gall bladder, and pancreas - Answer-bile is
produced in the liver and is sent out via the left or right hepatic ducts which join to form
the common hepatic duct
bile in the common hepatic duct can be sent to the gallbladder for storage, or be sent
directly to the duodenum for secretion
the common hepatic duct becomes the common bile duct after the gallbladder, and this
eventually joins with the pancreatic duct (along with all the pancreatic zymogens +
bicarb)
this digestive juice is secreted into the duodenum after passing through the ampulla of
vater and the sphincter of oddi
Describe the control of bile release - Answer-this is mediated by CCK primarily -- CCK
is secreted in response to a rising gastric pH and presence of fats in the chyme
CCK stimulates contraction of the gall bladder, as well as allows for relaxation of the
sphincter of oddi to release bile and pancreatic enzymes
Describe the flow of various substances through each zone in the liver - Answer-Both
oxygenated and deoxygenated blood flow from zone 1 to zone 3 -- via the hepatic artery
or portal vein ultimately to the hepatic vein
Bile flows "opposite" -- from zone 3 --> zone 1 (I.e. from the hepatic vein --> portal vein)
What are the 3 components contained within each liver lobule? - Answer-the portal triad
1. Portal vein
2. Portal arteriole
3. Bile duct
What is the blood supply for liver lobules? - Answer-80% from portal circulation (this is
deoxygenated blood)
20% from the hepatic artery (oxygenated)
Describe the basic pathologic complications that occur within each zone of the liver
lobule - Answer-Zone 1: most susceptible to infection by viral hepatitis -- this makes
sense because this zone is closest to the portal circulation, which brings blood back
from the GI tract to be detoxed, and hepatitis A and E are transmitted fecal-orally
,Zone 2: most affected by Yellow Fever
Zone 3: most susceptible to ischemia/necrosis given its distance from the blood supply,
there is also a high concentration of p450 enzymes here, fat accumulation begins here
(in EtOH abuse)
What are the two embryologic variants concerning the pancreas? - Answer-Note that
the pancreas arises from endodermal tissue and results from the fusion of two separate
buds, the dorsal and ventral buds.
1. Annular Pancreas: this occurs when the ventral bud fuses around the duodenum
(forms a ring around it) resulting in a small bowel obstruction
2. Pancreas Divisum: this occurs when there is failure of fusion of the dorsal and ventral
buds -- this is usually asymptomatic -- the buds function separately and drain into the
duodenum on their own
What structure can be utilized by the pancreas to bypass the sphincter of oddi? -
Answer-accessory pancreatic duct
What are the 3 main branches of the celiac trunk? - Answer-1. Common hepatic artery
2. Left gastric artery
3. Splenic artery
note that the R gastric artery is a branch of the common hepatic (common hepatic splits
into the R gastric and the hepatic artery proper)
Innervation of the gall bladder and liver - Answer-Parasympathetics from the vagus
nerve
Sympathetics from the celiac ganglion (likely some superior mesenteric ganglion as
well)
name and identify the embryologic remnants that persist in the adult liver - Answer-1.
Round ligament (ligamentum teres): surrounds the portal triad, best viewed from the
posterior aspect. This is a remnant of the fetal umbilical vein -- falciform ligament is part
of this as well
Describe the parts of the duodenum that are intra/retro-peritoneal - Answer-the
duodenum crosses the boundaries of retro/intra peritoneal due to its curvature/shape
,The 1st part is mainly intraperitoneal
2nd and 3rd parts are retroperitoneal
4th part is intraperitoneal (this is the transition from the duodenum to the jejunum - recall
this transition is marked by the ligament of treitz)
SMA syndrome is caused by compression of what aspect of the duodenum? - Answer-
usually occurs when the SMA impinges on the 3rd part of the duodenum, resulting in a
small bowel obstruction among other symptoms (nausea, bilious vomiting, anorexia,
etc.)
Difference between conjugated and unconjugated bilirubin - Answer-Unconjugated
(indirect) bilirubin is insoluble in water and is bound to albumin -- this is the product
directly after the macrophage breakdown of RBCs and heme
*conjugation process is done in the liver via the UDP-glucuronosyl-transferase enzyme*
Conjugated (direct) bilirubin is soluble in water -- this is the final product after
processing in the liver -- it is then excreted in the bile into the small intestine where it
becomes urobilinogen -- this is then excreted primarily (80%) in the feces as stercobilin
(brown stool), or in the urine (20%) as urobilin -- note that some urobilinogen is also
reabsorbed by the liver via enterohepatic circulation
Normal liver enzyme levels - Answer-AST: 12-38 U/L
ALT: 10-40 U/L
note that the ratio (AST/ALT) of these values should be close to 1 -- greater than 1
indicates liver damage and potentially cirrhosis
AST that is x2 the ALT indicates alcohol induced cirrhosis
("toAST 2 alcohol")
Provide an overview of primary biliary cholangitis - Answer-this is an autoimmune
disease mediated by autoantibodies against mitochondria (antimitochondrial antibodies
- AMA) that attack the bile ducts in the liver -- occurs with hyperlipidemia
this is a slowly progressive disease that often coexists with other autoimmune
conditions
patients present with fatigue, jaundice, pruritus, and other signs of cirrhosis as the
disease gets worse -- xanthomas around the eyes as well due to dysfunctional lipid
metabolism
, Histologically, there will be lymphocytic infiltration of the portal areas as well as
granulomatous changes to the periductal region -- ultimately this leads to destruction of
the bile ducts and a chronic cholangitis
Diagnostics:
- elevated serum ALP (occurs in gallbladder/liver dysfunction)
- possibly elevated AST/ALT depending on progression
- positive AMA titers (95% of patients have this)
- biopsy as described above, not necessary for diagnosis
Treatment:
- Ursodiol (ursodeoxycholic acid) -- this is a synthetic bile salt that when given will
decrease intestinal absorption of cholesterol and decrease hepatic synthesis of bile --
this puts less stress on the liver to try and produce bile -- improves prognosis
Pharmacologic therapy option for cholestasis - Answer-Ursodiol -- giving a synthetic bile
salt allows for the liver to rest
This decreases the intestinal absorption of cholesterol and decreases intrahepatic bile
production
recall that bile salts/acids are necessary for absorption of fats, and fat soluble vitamins
(A,D,E,K)
Histologic findings of primary sclerosing cholangitis - Answer-concentric (onion-skin
appearance) fibrotic deposits around both small and large bile ducts
will be p-ANCA positive on titers -- risk of glomerulonephritis as well
What is the tape test used for? - Answer-Diagnosis of enterobius vermicularris, a
helminth that often infects young children
the tape test is used by sticking a scotch like tape to the perianal region, then being able
to visualize the eggs of the helminth under the microscope
enterobiasis occurs predominantly in children that complain of perianal pruritus
Describe the pathophysiology of acetaminophen induced acute liver failure. Treatment?
- Answer-In normal dosing, the liver antioxidant glutathione is capable of clearing the
toxic metabolite of acetaminophen called NAPQI
At high doses, the liver's stores of glutathione are depleted, and this allows NAPQI to
build up and cause oxidative damage that is irreversible -- can lead to liver necrosis
Treatment:
- give activated charcoal if within 4 hours of ingestion
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