GI Flashcards
Hormone responsible for gallbladder contraction? Where made?
Cholecystokinin (CKK), which is made in duodenum and jejunum in response to FA’s and AA’s
Dubin-Johnson syndrome
Defect of hepatic excretion of bilirubin glucuronides across canalicular membrane (MDR2 biliary transport protein); Chronic conjugated hyperbilirubinemia; black liver; histo with epi metabolites within lysosomes. Icterus, mostly asymtompatic; Benign = no tx
Extrahepatic biliary atresia
Obstruction of extra hepatic bile ducts. Jaundice by wk 3-4 w/ cholestatic picture (dark urine, echoic stools, and conjugated hyperbilirubinemia)
Liver bx = intrahepatic bile ductular proliferation, portal tract edema, fibrosis, parenchyma cholestasis
Whipple disease
Middle-aged Caucasian males - diarrhea, wt loss, arthropathy, polyarthritis, psych, cardiac
Tropheryma whippeli - Gram + actinomycete. Only proliferates in macrophages = no inflammatory.
Bx - Enlarged FOAMY macrophages w/ rod-shaped bacilli and PAS-positive diastase-resistant granules
Tx = abx
Bile acid-binding resin names?
Cholestyramine, colestipol, colesevelam
What agents increase cholesterol content of bile?
Bile acid resins and fibrates
Mallory-Weiss v. Boerhaave
Mucosal tear v. transmural tear (esophageal air + fluid leak)
Where do H. pylori biopsy?
Prepyloric region of gastric antrum has highest yield.
Porcelain gallbladder
Refers to abdominal radiograph with bluish, brittle, Ca-laden gallbladder wall that develops in some patients with chronic cholecystitis. 11-33%->gallbladder carcinoma = advise cholecystectomy
How does H. pylori lead to duodenal ulcers?
Chronic antral inflammation -> decrease in delta cells (somatostatin-producing cells) -> disinhibition of gastrin. High gastrin -> increased H+ secretion by parietal cells.
Pathogenesis of TPN-induced gallstones
Biliary stasis 2/2 to dec. cholecystokinin
Insulin secretion from pancreatic beta cells?
Glucose stimulates. Enters via GLUT-2 (fac.) then generates ATP. High ATP:ADP causes CLOSURE of K+ channels (KATP). Beta cells now depolarize b/c K+ not leaving the cell and building up inside –> opening of voltage dependent Ca2+ channel -> insulin release. Sulfonylureas bind to KATP –> channel closure -> insulin release.
Gilbert syndrome
Mild UDP glucuroyl transferase transferase defieincy. Uncojugated hyperbilirubinemia, usu. provoked by hemolysis, fasting, exertion, febrile illness, etc. No clinical consequence.
Bilirubin system
Bilirubin transported to liver w/ albumin. Uptaked. Conjugated by UDP-Glucuronyl transferase (absent in Crigler Najjar and low in Gilbert) -> Secreted (defetive in Rotor and Dubin-Johnson) as bilirubin glucuronide. Turned into urobilinogen in GI. Some go back thru portal system to liver/urine. Others go to feces (brown).
Portacaval anastomoses
Varices = left gastric vein to esophageal vein. Hemorrhoids = superior rectal vein to middle/inferior rectal veins. Caput medusae = paraumbilical veins to superficial and inferior epigastric veins
Chronic mesenteric ischemia
Pt with atherosclerotic risk factors has pain after meals not responding to antacids and nothing on EGD. Due to atherosclerotic narrowing of celiac, SMA, IMA - not able to dilate in response to digestion.
Celiac disease pathology?
Atrophy of villi, flattening of mucosa, chronic inflammation of laminal propria. All reversible w/ gluten-free diet.
Foregut and blood supply
Esophagus, stomach, liver, gallbladder, pancreas, upper duodenum. Celiac
Midgut and blood supply
Lower duodenum, small intestine, ascending colon, proximal 2/3 of transverse colon. SMA
Hindgut and blood supply
Distal third of transverse, descending, sigmoid. IMA.
Midgut rotation
Midgut herniates through umbilical ring at wk 6 b/c slower growth of abdominal cavity. Return at wk 10 and completes 270 deg turn CCW around the SMA.
Pancreas divisum
Failure of ventral and dorsal buds to fuse at wk 8. Asymptomatic.
How does pregnancy predispose to gallstone formation?
Estrogen-induced HMG-CoA reductase activity = cholesterol hypersecretion. Progesterone induces gallbladder hypomotility
Hirschsprung disease path
RECTAL biopsy. Failure of neural crest cells to migrate to intestinal wall. Submucosa will demonstrate absence of ganglionic cells (Meissner). Rectum always involved (wk 12), sigmoid 75%. Present will failure to pass meconium within 48 hrs, intestinal obstruction.
Final pathway of pancreatitis pathogenesis following acinar cell injury
Intra-acinar conversion of trypsinogen to active trypsin! This leads to other activation (elastase, chymotrypsin, phospholipase)). Proteases auto digest. Elastase leads to vascular dmg and hemorrhage. Lipase/phospholipase -> fast necrosis
Reflux esophagitis patho
Elongation of papillae, basal cell hypertrophy, intraepithelial eosinophils
Primary Biliary Cirrhosis
Chronic. Autoimmune destruction of INTRAhepatic bile ducts and CHOLESTASIS. Middle-aged women, insidious. PRURITIS (esp. night), fatigue. Hepatosplenomegaly, xanthomatous lesions. Jaundice, steatorrhea, portal HTN. Labs - elevated alkPhos, cholesterol, and serum IgM. Dx = anti-mitochondrial antibodies. Associated w/ Sjogren’s, Raynaud’s scleroderma, autoimmune thyroid, hypothyroidism, and celiac disease
Hereditary pancreatitis
Mutations in trypsinogen or SPINK1 (trypsin inhibitor). Mot common mut -> abnl trypsin that is not susceptible to inactivating cleavage by trypsin.
True vs. pseudodiverticulum
True diverticula contain mucosa, submucosa, AND muscular layers. e.g. Meckel’s is failure of obliteration of vitelline duct (usu. wk 7). 2% of pop, 2 feet from ileocecal valve, 2 inches in length, 2% symptomatic, males 2x more affected. False diverticula DON’T contain muscularis (e.g. colonic and Zenker’s)
Ballooning degeneration of liver?
Hepatocyte swelling found along with mononuclear infiltrates and Councilman bodies histologically during acute viral hepatitis. Regeneration nodules found in chronic hepatitis.
Peptic ulcer disease ulcer sites?
First portion of duodenum within 3 cm of pylorus. Distal ulcers are not common (think Zollinger-Ellison)
Zenker diverticulum
Oftentimes, cricopharyngeal dysfunction leads to increased pharyngeal contractions required for swallowing b/c of diminished relaxation. (Traction diverticulum contains ALL layers).
How does HBV induce HCC?
Thought to be triggered by integration of viral DNA into genome. Synthesis of insulin-like growth factors, suppresses p53, chronic inflammation and regeneration.
Pernicious anemia pathology?
Parietal cell damage. Appear pale pink, round, plate-like in the upper gland layers. Loss of intrinsic factor-secreting parietal cells, marked infiltration by lymphocytes and plasma cells, and megaloblastic changes. (Chief cells that secrete pepsinogen are found in deeper glandular layers - small basophilic)
Brown pigment gallstones?
Usu. secondary to infection of biliary tract (E. coli, Ascarin, Opisthorchis sinuses). Injured hepatocytes and bacteria release Beta-glucuronidase -> hydrolysis of bilirubin glucoronides -> inc. unconjugated bilirubin in bile.
Schilling test
Used to ID cause of B12 deficiency. (1) Oral radio B12 w/ IM non-B12 (to ensure excretion) and check urine. If lots of urine radio B12 = good absorption and poor diet. If low radio B12 = poor absorption. Phase II = radio labeled B12 w/ intrinsic factor. If still high radio B12, then still poor absorption not corrected by IF (e.g. pancreatic insufficiency, ileal disease, intestinal bacterial overgrowth)
How does octreotide work?
It is a somatostatin analog. Inhibits glucagon and VIP —> reduced vasodilation –> splanchnic vasoconstriction w/o systemic vasoconstriction. Helpful for esophageal varices.
Palpable but NONtender gallbladder, wt loss, obstructive jaundice (pruritus, dark urine, pale stool)
Adenocarcinoma of the head of the pancreas compressing the common bile duct
Annular pancreas
Abnormal encirclement of the duodenum by the ventral pancreatic bud -> duodenal narrowing
What parts of the GI are retroperitoneal?
Lower 2/3 of esophagus. 2-4th part of the duodenum. Ascending and descending colon. Part of the rectum.
Retroperitoneal structure acronym
SAD PUCKER = Suprarenal glands, Aorta + IVC, Duodenum (2-4), Pancreas (except tail), Ureter, Colon (Des. and asc.), Kidneys, Esophagus (lower 2/3), Rectum
Falciform ligament
Connects liver to ant. abdominal wall. Contains ligamentum teres hepatic (fetal umbilical vein.).
Hepatoduodenual ligament
Contains the portal triad. Therefore, the Pringle maneuver (compressing ligament w/ one finger in lesser sac via omental foramen) controls bleeding.
Gastrohepatic ligament
Liver to LESSER curvature. Contains the gastric arteries.
Gastrosplenic ligament
Greater curvature to spleen. Contains the SHORT gastrics and L gastroepiploic vessels.
Splenorenal ligament
Contains splenic artery and vein. Tail of pancreas.
Where are Peyer’s patches found?
In the lamina propria and submucosa of the Ileum
Crypts of Lieberkuhn found where in GI?
Small and large intestine. NOT stomach (it has gastric glands).
Where are villi found in the GI?
Small intestine but NOT colon.
What GI regions does the vagus nerve and pelvic nerve innervate?
Pelvic nerve innervates hindgut (distal 1/3 of transverse colon to upper portion of rectum). Rest in vagus.
Three main branches of the celiac trunk?
Common hepatic, splenic, and left gastric.
Superior and inferior epigastric arteries anastomose what major systems?
Internal thoracic/mammary with external iliac.
Superior and inferior pancreaticoduodenal arteries anastomose what major systems?
Celiac and SMA
Middle colic and left colic arteries anastomose what major systems?
SMA and IMA
Superior rectal and middle/inferior rectal arteries anastomose what major systems?
IMA and the internal iliac.
Pectinate line - above & below arterial and venous
Above - superior rectal a. from IMA. Venous from superior rectal v. to IMV to portal system. Below - Inferior rectal a. from internal pudendal a. Inferior rectal vein to internal pudendal vein to internal iliac to IVC
Flow of bile and blood in the liver?
Blood flows from the portal triad (portal a. and vein) into the central vein (to hepatic veins and systemic circulation). Bile flows into the bold ductule.
Zones of the liver
Zone 1 = periportal and is first affected by viral hepatitis and ingested toxins. Zone 3 = (Centrilobular) pericentral vein zone and is affected 1st by ischemia = acetaminophen tox. Site of alcoholic hepatitis, CYP-450 system.
Femoral vessel organizatoin?
NAVEL is lateral to medial. Nerve, artery, vein, empty space, lymphatics.
Indirect vs. direct inguinal hernia
Lateral to epigastric vessels vs. medial to (in Hesselbach). Into the scrotum vs. only through external/superficial ring.. Infants/young ppl vs. older men.
Gastrin - action and regulation
Increases parietal cell H+ secretion, hypertrophies the gastric mucosa, (and increases gastric motility). Activated by stomach distention/alkalinzation, aa’s, peptides, and vagal stimulation. Repressed by a stomach pH < 1.5. Phenylalanine and tryptophan are particularly potent stimulators.
Gastrin produced where?
G-cells in the antrum of the stomach. (Zollinger-Elilson syndrome - gastrinoma)
CCK’s 5 major effects; How is it activated?
Contraction of gallbladder + relaxation of Oddi, secretion of pancreatic enzymes, secretion of HCO3 from pancreas, trophic effects on pancreas and gallbladder, inhibition of gastric emptying. Activated by FA’s and AA’s. Actions via neural muscarinic pathways.
CCK source
I cells of the duodenum and jejunum.
D, I, G, K, S cells are where and produce what?
D is pancreatic islets and GI mucosa; somatostatin. I cells are duodenum/jejunum and CCK. G is antrum of stomach and gastrin. K is duodenum and jejunum and GIP. S is duodenum and secretin.
Secretin’s actions and stimulation?
Stimulated by acid, FA’s in lumen of duodenum. Increases pancreatic bicarb, bile secretion, and DECREASED gastrin effects (H+). All for a better pH for pancreatic enzymes.
GIP’s actions and stimulation
Exocrine function is DEC. gastric H+ secretion while endocrine function is INC. insulin release. Stimulated by FA’s, aa’s, oral glucose.
Motilin function and activation
Increases in fasting state and produces migrating motor complexes. Made in small intestinee.
Somatostatin function and activation.
Activated by acid and inhibited by vagal stimulation. It is the INHIBITORY and anti-growth hormone. Decreased gastric acid and pepsinogen, pancreatic and small intestine fluid sections, dec. gallbladder contraction, dec. insulin and glucagon release
VIP source?
Parasympathetic ganglia in sphincters, gallbladder, small intestine. Or VIPoma - non-alpha, non-beta islet cell pancreatic tumor.
VIP function and activation?
Increases intestinal water and electrolyte secretion while relaxing intestinal smooth muscles and sphincters. Activated by distention and vagal stimulation. Inhibited by adrenergic input.
VIPoma symptoms?
WDHA syndrome. Watery Diarrhea, Hypokalemia, Achlorhydria.
Intrinsic factor f(x) and made where?
Made by parietal cells and is the vitamin-B12 binding protein for uptake in terminal ileum
Pepsin’s function and regulation?
Protein digestion. Activated by vagal stimulation and local acid (secreted by CHIEF cells in stomach). Pepsinogen to pepsin via H+.
What produces HCO3 in the GI tract?
Mucosal cells of the stomach, duodenum, salivary glands, and pancreas. As well as Brunner glands in the duodenum. Pancreatic and biliary secretion of HCO3 with secretin.
Gq acting substances on the gastric parietal cell?
Vagus nerve via Ach-M3 and GRP to G-cell -> Gastrin onto CCKb receptor.
cAMP acting substances on gastric parietal cell
Gs - Histamine from ECL cells. Gi - Prostaglandin/misoprostol and somatostatin.