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Which ligament contains the portal triad?
Hepatoduodenal
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What does the falciform ligament contain, and what fetal structure is it derived from?
Ligamentum teres, derived from the fetal umbilical ligament
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Which layer of the gut is Meissner's plexus found in?
Submucosa
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Which layer of the gut is Auerbach's plexus found in?
Muscularis externa
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Level of celiac trunk
T12
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Level of bifurcation of aorta
L4
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Artery that can be eroded by duodenal ulcer
Gastroduodenal branch of common hepatic
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Anastamoses that develop if abdominal aorta is blocked
- Internal thoracic (subclavian)--epigastrics
- Superior pancreaticoduodenal (SMA)--inferior pancreaticoduodenal (IMA)
- Middle colic (SMA)--left colic (IMA)
- Superior rectal (IMA)--middle rectal (internal iliac)
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Three portal systemic anastomoses and the their clinical symptoms
- Left gastric--esophageal (esophageal varices)
- Paraumbilical--superior and inferior epigastrics (caput medusae)
- Superior rectal--middle and inferior rectal (internal hemorroids)
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Zone of liver most vulnerable to toxic and ischemic injury
Zone III, around central vein (poorly perfused)
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Structures found in femoral sheath
Femoral artery, vein, and deep inguinal lymph nodes (not femoral nerve)
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Indirect inguinal hernia
- Enters internal inguinal ring lateral to epigastric artery
- Occurs in infants due to failure of processus vaginalis to fuse
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Direct inguinal hernia
- Protrudes through inguinal triangle (borders are femoral nerve, sartorious muscle, and inguinal ligament), medial to inferior epigastric artery
- Seen in older men
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Femoral hernia
- Protrudes under inguinal ligament, lateral to pubic tubercle
- More common in women
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GIP
- Secreted from K cells of the duodenum
- Decreases gastric acid secretion
- Increases insulin secretion
- Release is activated by oral glucose (which triggers insulin secretion more effectively than IV glucose)
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Functions of VIP
- Increases electrolyte and water secretion in the intestine
- Relaxes intestinal smooth muscle and sphincters
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Cells that secrete gastric acid
Parietal cells of stomach
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Regulation of gastric acid secretion
- Upregulated by gastrin, ACh, and histamine
- Downregulated by somatostatin, GIP, prostaglandins, and secretin
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Effect of atropine on stomach secretions
- Inhibits vagal stimulation of parietal cells, blocking gastric acid and B12 release
- Does not affect G cells that release gastrin, since G cells are activated by GRP, not ACh
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Mechanism of gastrin-mediated acid increase
Gastrin acts primarily on ECL cells, causing them to release histamine, which triggers parietal cells to release acid. Its direct effect on parietal cells is minimal
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Gland that secretes the most mucinous saliva
Parotid
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Intracellular effect of prostaglandins on parietal cells
Decrease intracellular cAMP, which inhibits acid secretion
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Only submucosal glands found in the GI tract
- Brunner's glands, located in duodenal submucosa
- Secrete alkaline mucus to neutralize acid gastric contents entering duodenum
- Hypertrophy in peptic ulcer disease
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Trypsinogen
- Secreted from the pancreas, activated to trypsin by enterokinase on the intestinal brush border
- Function is to activate other pancreatic proenzymes
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Three steps to carbohydrate digestion
- Salivary amylase hydrolyzes alpha 1,4 linkages to yield disaccharides
- Pancreatic amylase hydrolyzes starch into di/oligosaccharides
- Oligosaccharide hydrolases on intestinal brush border produce monosaccharides (rate limiting step)
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Where are divalent cations (iron, magnesium, calcium) absorbed?
Duodenum
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Where is folate absorbed?
Jejunum
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Where are B12 and bile acids absorbed?
Ileum
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Enzyme that converts unconjugated bilirubin to conjugated bilirubin
UDP glucouronyl transferase
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Warthin's tumor
A benign mass of salivary gland tissue trapped in a lymph node
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Increased risk of esophageal carcinoma
Associated with achalasia
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Lye ingestion
Associated with esophageal strictures
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Pathogens that invade the esophagus
HSV1, CMV, candida
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Plummer-Vinson syndrome
Triad of dysphagia, due to esophageal webs, glossitis, and iron-deficiency anemia
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Dermatitis herpitiformis
Associated with celiac
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Patient presents with arthralgia and cardiac and neural symptoms. Biopsy shows PAS positive macrophages in the intestinal lamina propria
Whipple's disease, infection with T. whippelli
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Menetrier's disease
Gastric hypertrophy with parietal cell atrophy. Precancerous
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Enlargement of the left supraclavicular lymph node
Virchow's node, may indicate gastric adenocarcinoma
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Most likely cause of a duodenal ulcer
H. pylori
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Most common site of Crohn's manifestations
Terminal ileum and colon
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Most common site of UC involvement
End of the GI tract--the rectum is always involved
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Transmural v. mucosal inflammation in inflammatory bowel disease
- Crohn's--transmural inflammation
- UC--submucosal inflammation
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Inflammatory bowel disease with granulomas
Crohn's
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Extraintestinal manifestations of Crohn's
- Migratory polyarthritis
- Erythema nodosum
- Ankylosing spondylitis
- Uveitis
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What is primary sclerosing cholangitis associated with?
UC
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Mechanism of gallstone formation in Crohn's
Impaired bile acid reabsorption from the terminal ileum increases cholesterol concentration in the bile
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Mechanism of renal stones in Crohn's
- Normally, Ca binds to oxalate in the GI tract and inhibits its absorption
- In Crohn's, Ca levels are low
- Lack of Ca increases oxalate absorption, resulting in the formation of Ca-oxalate stones
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Most common cause of appendicitis in children
Lymphoid hyperplasia, usually following a viral infection
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Most common cause of appendicitis in adults
Fecalith
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Most common location for a diverticulum
Sigmoid colon
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Zenker's diverticulum
- Herniation of mucsoal tissue at pharyngoesophageal junction
- False diverticulum, does not involve all 3 gut layers
- Presents with halitosis and dysphagia
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Meckel's diverticulum
- Persistence of the vitelline duct or yolk sac
- True diverticulum
- May contain ectopic acid-secreting gastric tissue, which can cause bleeding ulcers (bloody stools)
- Usually presents in first two years of life
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Virus that can trigger intussusception of the bowel in children
Adenovirus
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Duodenal atresia
- Failure of duodenum to recanalize during embryonic development
- Presents with early bilious vomiting
- Associated with Down's
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Most common locations of ischemic colitis
Splenic flexure and distal colon
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Gene mutations associated with colon cancer
- APC--early mutation
- K-ras--seen in late adenomatous polyps
- p53--late mutation in adenocarcinoma
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Hyperplastic polyp
- Most common non-neoplastic colon polyp
- Most often found in rectosigmoid colon
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Peutz-Jeghers syndrome
- AD syndrome
- Multiple, non-malignant hamartomatous polyps in GI tract, with increased risk of colorectal cancer
- Hyperpigmentation of mouth, hands, and genitalia
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FAP
- AD mutation in APC gene leads to unregulated beta catenin activity
- Many, many colon polyps
- Always involves rectum
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Gardener's syndrome
FAP plus bone tumors and retinal hyperplasia
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Lynch syndrome
- Autosomal dominant mutation resulting in mismatch repair
- Always involves proximal colon
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Apple core lesion on barium enema X-ray
Colorectal cancer
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Will a non-metastatic carcinoid tumor in the GI tract be asymptomatic?
No, because serotonin is metabolized in the liver
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ALT is much higher than AST
Viral hepatitis
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AST is much higher than ALT
Alcoholic hepatits (remember that AST is a mitochondrial enzyme)
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Elevated GGT
Alcohol abuse
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Elevated alk phos
Obstructive liver disease, bone disease, bile duct disease
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Low ceruloplasmin
Wilson's disease
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Viruses associated with Reye's syndrome
VZV, influenza B
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Mechanism of Reye's disease
Aspirin metabolites decrease beta oxidation of fatty acids by reversible inhibition of mitochondrial enzymes
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Most likely cause of a liver tumor
Metastasis
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Factors associated with increased incidence of hepatocellular carcinoma
- Hep B and C
- Wilson's disease
- Hemochromatosis
- Alpha 1 antitrypsin deficiency
- Alcoholic cirrhosis
- Aflatoxins
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Budd-Chiari syndrome
- Obstruction of the hepatic vein (may be due to IVC obstruction or right heart failure)
- Presents with a triad of abdominal pain, ascites, and hepatosplenomegaly
- Associated with polycythemia vera, pregnancy, and hepatocellular carcinoma
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Alpha 1 antitrypsin deficiency
- Co-dominant inheritance, causes a misfolded gene product
- Panacinar emphysema and increased risk of HCC
- PAS positive intracellular inclusion bodies seen in liver
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Cause of physiologic neonatal jaundice
- Immature UDP glucouronyl transferase
- Treat with phototherapy to convert unconjugated bilirubin to a water soluble form
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Obstructive jaundice causes an increase in which form of bilirubin?
Conjugated
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Hemolytic jaundice causes an increase in which form of bilirubin?
Unconjugated (not water soluble)
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Gilbert's syndrome
- Mild decrease in UDP glucouronyl transferase
- Elevated unconjugated bilirubin during stress (e.g. fasting, infection)
- Benign
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Crigler-Najjar type I
- Absent UDP glucouronyl transferase
- Presents with increased unconjugated bilirubin, jaundice, and kernicterus
- Patients typically die within a few years
- (Type II is a mild form of Crigler-Najjar that can be treated with barbiturates)
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Dubin-Johnson syndrome
- Defective bilirubin excretion causes conjugated hyperbilirubinemia
- Liver is black
- Asymptomatic
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Symptoms of Wilson's disease
- Low ceruloplasmin, high copper
- Asterixis
- Basal ganglia degeneration, giving rise to Parkinson-like symptoms
- Cirrhosis
- Kaiser-Fleischer rings
- Heptaocellular carcinoma
- Dementia
- Hemolytic anemia
- Renal tubular acidosis
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Treatment for Wilson's disease
Penicillamine or trientine
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Classic triad of hemochromatosis
- Diabetes mellitus
- Micronodular cirrhosis
- Hyperpigmentation
- (also causes CHF--major cause of death)
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Primary biliary cirrhosis
- Autoimmune destruction of the bile ducts with lymphocytic infiltrate and granuloma formation
- Anti-mitochondrial antibodies in serum
- Hypercholesterolemia, steatorrhea, jaundice, dark urine, light stool
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Conditions associated with primary biliary cirrhosis
- CREST
- Celiac
- Rheumatoid arthritis
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Primary sclerosis cholangitis
- Concentric fibrosis of the bile ducts with onion skin appearance
- Pattern of alternating strictures and dilations gives rise to "beading" appearance
- Presents with pruritus, jaundice, light stool, and dark urine
- Associated with ulcerative colitis and high serum IgM
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Substances that keep cholesterol dissolved in the gall bladder
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Effect of progesterone on the gall bladder
Progesterone inhibits gall bladder motility and decreases bile acid secretion, predisposing to gall stones
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Pigment bile stones
Radioopaque (unlike cholesterol stones), seen in patients with chronic hemolytic anemia
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Palpable, non-painful gall bladder
Pancreatic tumor obstructing bile duct
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Analgesic of choice for treating cholecystitis
Meperidine, which, unlike most opiates, does not cause the sphincter of Oddi to spasm
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Two most common causes of pancreatitis
Gall stones, alcohol abuse
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Markers of pancreatic cancer
CEA, CA-19
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Signs of pancreatic cancer
- Abdominal pain radiating to the back
- Weight loss
- Obstructive jaundice with palpable gall bladder
- Migratory thrombophlebitis (redness and tenderness of extremities on palpation)
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