Gastrointestinal Tract Development Quiz
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Questions and Answers

Which embryonic layer gives rise to the gastrointestinal tract?

  • Endoderm (correct)
  • Neuroectoderm
  • Mesoderm
  • Ectoderm

    • The ventral mesentery is present throughout the entire gastrointestinal tract.

    False

    What is the first step in the chromosomal instability pathway leading to colon cancer?

  • K-RAS mutation
  • p53 mutation
  • DCG gene mutation
  • APC mutation (correct)

    • What condition results from abnormal development of the tracheoesophageal septum?

    <p>Esophageal atresia</p> Signup and view all the answers

    The _____ omentum hangs from the greater curvature of the stomach.

    <p>greater</p> Signup and view all the answers

    Familial Adenomatous Polyposis (FAP) is an autosomal recessive disorder.

    <p>False</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Foregut = Mouth to Ampulla of Vater Midgut = Ampulla of Vater to transverse colon Hindgut = Transverse colon to rectum Dorsal mesentery = Grows between gut and posterior wall</p> Signup and view all the answers

    What does a loss of the p53 tumor suppressor gene lead to?

    <p>Tumor cell growth</p> Signup and view all the answers

    The APC gene mutation increases the risk of developing _____ in the colon.

    <p>polyps</p> Signup and view all the answers

    Which artery supplies the midgut?

    <p>Superior mesenteric artery (SMA)</p> Signup and view all the answers

    Which syndrome is characterized by polyposis and benign bone growths?

    <p>Gardner's Syndrome</p> Signup and view all the answers

    Retroperitoneal organs are completely enclosed by peritoneum.

    <p>False</p> Signup and view all the answers

    What organ buds off from the foregut during embryonic development?

    <p>Lungs</p> Signup and view all the answers

    Match the following mutations with their effects in colon cancer progression:

    <p>APC = Increases β-catenin level K-RAS = Aberrant cell signaling p53 = Tumor cell growth</p> Signup and view all the answers

    Congenital Hypertrophy of the Retinal Pigment Epithelium (CHRPE) usually has significant symptoms.

    <p>False</p> Signup and view all the answers

    Colon removal due to Familial Adenomatous Polyposis is referred to as _____ procedure.

    <p>colectomy</p> Signup and view all the answers

    Which type of tumors are primarily associated with Turcot Syndrome?

    <p>Medulloblastomas</p> Signup and view all the answers

    Microsatellite instability is more commonly associated with left-sided colon cancers.

    <p>False</p> Signup and view all the answers

    What is the genetic condition that leads to an inherited mutation of DNA mismatch repair enzymes?

    <p>HNPCC or Lynch Syndrome</p> Signup and view all the answers

    The _______ gene is frequently mutated in advanced colorectal cancers.

    <p>DCC</p> Signup and view all the answers

    Match the following colon cancer symptoms with their corresponding sites:

    <p>Right-sided = Weight loss Left-sided = LLQ Pain</p> Signup and view all the answers

    What is the third most common cancer?

    <p>Colon cancer</p> Signup and view all the answers

    Regular digital rectal exams are unnecessary if fecal occult blood testing is negative.

    <p>True</p> Signup and view all the answers

    Which bacterium is strongly associated with colon cancer?

    <p>Strep Bovis</p> Signup and view all the answers

    Aspirin therapy is believed to reduce the risk of colorectal cancer by ______ to ______ percent.

    <p>20</p> Signup and view all the answers

    What is a common site of metastasis for colon cancer?

    <p>Liver</p> Signup and view all the answers

    What is the primary clinical feature of esophageal atresia?

    <p>Esophagus does not connect to stomach</p> Signup and view all the answers

    Omphalocele involves intestines covered by a membrane outside the body.

    <p>True</p> Signup and view all the answers

    Name one congenital abnormality associated with Meckel’s diverticulum.

    <p>Orofacial clefts, Trisomy 21, or any other genetic defect</p> Signup and view all the answers

    In gastroschisis, the bowel extrudes through the ______ wall.

    <p>abdominal</p> Signup and view all the answers

    Match the following conditions with their characteristics:

    <p>Esophageal Atresia = Cannot pass NG tube into stomach Gastroschisis = Not covered by peritoneum Meckel’s Diverticulum = Outpouching of ileum Omphalocele = Covered by peritoneum</p> Signup and view all the answers

    Which enzyme is primarily responsible for lipid digestion in adults?

    <p>Pancreatic lipase</p> Signup and view all the answers

    A left sided colon is an anatomic variant.

    <p>True</p> Signup and view all the answers

    What is the term for the condition where air accumulates in the stomach due to a fistula between the esophagus and trachea?

    <p>Gastric distension</p> Signup and view all the answers

    Salivary fluid produced by acinar cells is modified by ______ cells.

    <p>ductal</p> Signup and view all the answers

    What is a common consequence of malrotation in midgut development?

    <p>Vascular compromise</p> Signup and view all the answers

    Saliva becomes hypotonic from the removal of sodium and chloride.

    <p>True</p> Signup and view all the answers

    What is the major function of saliva in the digestive process?

    <p>To assist in the digestion of carbohydrates and lipids.</p> Signup and view all the answers

    Persistent vitelline duct development can lead to _______ diverticulum, the most common congenital GI abnormality.

    <p>Meckel’s</p> Signup and view all the answers

    Match the following salivary electrolytes with their effects:

    <p>Na = Increases saliva isotonicity K = Raises pH in saliva Cl = Lower concentration in saliva HCO3- = Protects against acid</p> Signup and view all the answers

    Which of the following is produced in the liver and plays a crucial role in lipid absorption?

    <p>Bile</p> Signup and view all the answers

    Bile is exclusively composed of cholesterol.

    <p>False</p> Signup and view all the answers

    What can excessive levels of bilirubin in the blood indicate?

    <p>Hyperbilirubinemia</p> Signup and view all the answers

    Bile salts are necessary for __________ absorption.

    <p>lipid</p> Signup and view all the answers

    Match the type of bilirubin with its property:

    <p>Conjugated Bilirubin = Water soluble Unconjugated Bilirubin = Not water soluble Direct Bilirubin = Can be detected in urine Indirect Bilirubin = Must be mixed with alcohol for detection</p> Signup and view all the answers

    What is the primary site of dysfunction in hepatocellular damage?

    <p>Hepatocytes</p> Signup and view all the answers

    Jaundice is characterized by the yellowing of the skin and mucous membranes due to elevated bilirubin levels.

    <p>True</p> Signup and view all the answers

    What is the best initial test for diagnosing cholestasis?

    <p>Right upper quadrant ultrasound</p> Signup and view all the answers

    Alpha-1 antitrypsin deficiency can cause __________ liver disease.

    <p>cirrhotic</p> Signup and view all the answers

    Match the following conditions with their bilirubin patterns:

    <p>Hemolysis = Increased Unconjugated Bilirubin Biliary Obstruction = Increased Conjugated Bilirubin Liver Disease = Mixed Increase of Bilirubin Primary Biliary Cirrhosis = Intrahepatic Cholestasis</p> Signup and view all the answers

    Which of the following factors can lead to elevated levels of alkaline phosphatase (Alk Phos) in liver function tests?

    <p>Cholestasis pattern</p> Signup and view all the answers

    Elevated urine bilirubin indicates the presence of unconjugated bilirubin in urine.

    <p>False</p> Signup and view all the answers

    What leads to clerical changes in bile ducts during liver disease?

    <p>Bile duct obstruction</p> Signup and view all the answers

    Conversion of unconjugated bilirubin in the intestines leads to the production of __________.

    <p>urobilinogen</p> Signup and view all the answers

    What is the primary cause of portal hypertension?

    <p>Cirrhosis leading to obstructed flow through the liver</p> Signup and view all the answers

    Patients with cirrhosis without portal hypertension can develop ascites.

    <p>False</p> Signup and view all the answers

    What is the Serum Ascites Albumin Gradient (SAAG) used for?

    <p>To differentiate the causes of ascites, primarily between portal hypertension and malignancy.</p> Signup and view all the answers

    Ascites is the accumulation of fluid in the __________ cavity.

    <p>peritoneal</p> Signup and view all the answers

    Match the gastrointestinal condition with its primary feature:

    <p>Portal Hypertension = Increased pressure in portal vein Crohn’s Disease = Granulomatous inflammation Ascites = Fluid accumulation in peritoneal cavity Hypersplenism = Low platelet count</p> Signup and view all the answers

    What physical exam finding is associated with portal hypertension?

    <p>Caput Medusa</p> Signup and view all the answers

    Esophageal varices can lead to upper gastrointestinal bleeding.

    <p>True</p> Signup and view all the answers

    What type of antibodies are associated with Crohn’s disease?

    <p>Anti-saccharomyces cerevisiae antibodies (ASCA)</p> Signup and view all the answers

    In Crohn's disease, __________ inflammation affects the entire wall of the gastrointestinal tract.

    <p>transmural</p> Signup and view all the answers

    Which factor is a common extra-intestinal manifestation of Crohn’s Disease?

    <p>Migratory polyarthritis</p> Signup and view all the answers

    Smoking is known to improve outcomes in Crohn’s disease.

    <p>False</p> Signup and view all the answers

    What structural change occurs in the bowel wall during Crohn's disease?

    <p>Creeping fat</p> Signup and view all the answers

    The area most commonly affected by Crohn's disease is the __________ ileum.

    <p>terminal</p> Signup and view all the answers

    Match the following medications with their use:

    <p>Infliximab = Biologic therapy for IBD Methotrexate = Immunosuppressant for Crohn's Sulfasalazine = Treatment for Ulcerative Colitis Corticosteroids = Anti-inflammatory medication</p> Signup and view all the answers

    Study Notes

    Gastrointestinal Embryology

    • The gastrointestinal (GI) tract develops from the endoderm
    • Many abdominal organs bud off from the GI tract (e.g. liver, pancreas, trachea)
    • Mesoderm forms the surrounding structures of the GI tract (e.g., GI tract connective tissue, muscles, peritoneum, spleen)
    • Day 12: Mesoderm formation
    • Day 23: Amniotic sac enlargement
    • The foregut, midgut, and hindgut are divisions of the GI tract
    • Foregut: mouth to ampulla of Vater
    • Midgut: ampulla of Vater to transverse colon
    • Hindgut: transverse colon to rectum
    • The mesentery suspends abdominal organs from the cavity walls
    • Intraperitoneal organs are enclosed by the mesentery
    • Retroperitoneal organs are covered by peritoneum only on the anterior wall and lie against the posterior abdominal wall
    • Dorsal mesentery moves away from the posterior wall during development
    • Ventral mesentery exists only at the bottom of the esophagus, stomach and upper duodenum
    • In adults, the ventral mesentery becomes lesser omentum and falciform ligament
    • Mesogastrium, mesoduodenum, mesocolon are parts of the mesentery
    • Greater omentum hangs from the greater curvature of the stomach and covers the intestines
    • Lesser omentum is between the stomach and liver and formed from the ventral mesentery
    • Lung buds originate from the foregut
    • Tracheoesophageal septum divides the respiratory diverticulum into separate trachea and esophagus
    • Abnormal septum development may result in esophageal atresia
    • Esophageal atresia (closed esophagus) occurs when the septum deviates posteriorly
    • Types of esophageal atresia; EA with TEF (most common), Pure EA, H-Type
    • Characteristics of esophageal atresia may include esophageal does not connect to stomach, polyhydramnios, drooling, choking, vomiting, no passing of NG tube into stomach and fistula esophagus → trachea
    • Treatment for esophageal atresia is surgical repair
    • Midgut herniation occurs in the 6th week of development
    • In the 6th week, the abdominal cavity is too small to accommodate the growing intestines
    • The intestines temporarily herniate through the umbilical cord during development
    • A persistence of normal herniation is omphalocele
    • omphalocele= Intestines covered by membrane outside body
    • Liver does not hernia if lateral embryonic folds fail, which may contribute to the liver in omphalocele
    • Omphalocele key features include covering by peritoneum and through the umbilical cord
    • Many genetic defects are associated with omphalocele (e.g., Trisomy 21, Down syndrome; Trisomy 18, Edwards syndrome; Trisomy 13)
    • Other conditions associated with omphalocele include congenital heart defects, orofacial clefts, and neural tube defects
    • Gastroschisis is extrusion of bowel through abdominal wall
    • The exact mechanism for gastroschisis is unclear, however it is likely incomplete closure of the abdominal wall
    • Gastroschisis is usually on the right side of the umbilical cord
    • Gastroschisis is not covered by the peritoneum
    • Poor GI function, atresia, stenosis are often associated with gastroschisis
    • If GI function is restored, prognosis is good
    • Rarely associated with Down's syndrome or other congenital disease
    • Abnormalities at Abdominal Wall Defect can include omphalocele which has an umbilical defect, is covered by membrane and usually has normal bowel function, and gastroschisis which has a paraumbilical defect, is not covered by membrane, and usually has poor bowel function
    • During physiologic herniation bowel rotates around the SMA
    • Malrotation can lead to obstruction if cecum is positioned in the mid-upper abdomen
    • Peritoneal tissue = Ladd bands
    • Duodenal obstruction=common with malrotation
    • Volvulus is small bowel twisting around the SMA
    • This can cause vascular compromise, ischemia, vomiting, sepsis, abdominal distention, blood in the stool
    • Treatment of malrotation is surgical intervention
    • Vitelline duct pathology occurs in early development during which the midgut is open to the yolk sac.
    • By week 5, the connection with the yolk sac narrows, which are also known as the yolk stalk, vitelline duct, and omphalomesenteric duct
    • Persistent vitelline duct may lead to congenital anomalies
    • Mecel's diverticulum is the most common vitelline duct anomaly, which presents as cysts or polyps
    • A ''true diverticulum'' contains all layers of the bowel, mucosa, submucosa, muscular layer
    • Most diverticula only contain mucosa/submucosa
    • Often a small defect/hole in the the muscular layer of a diverticulum
    • Ectopic gastric tissue is sometimes in a Meckel's diverticulum
    • Typically no symptoms in Meckel's diverticulum but in some cases, it can result in symptoms like abdominal pain, potential cause of obstruction or diverticulitis, and bleeding
    • Rule of 2’s are 2% of population, Male-to-female 2:1; Within 2 feet from ileocecal valve and Usually 2 inches in size
    • Other vitelline anomalies can include cysts, cavity behind umbilicus and persistent duct which can result in intestinal discharge from umbilicus
    • Atresia is closed/absent opening, Stenosis is a narrowing/obstruction; Duodenum is the most common location for these disorders
    • Failure of recanalization in early development may result in duodenal occlusion due to endodermal proliferation of epithelium
    • The double bubble sign is commonly seen with duodenal atresia
    • Jejunal-Ileal-Colonic Atresia results from vascular disruption resulting in ischemic necrosis of the intestine
    • The necrotic tissue is resorbed resulting in blind ends of the bowel via arterial ligation
    • The bowel distal to the blind end may be curled ("Apple peel atresia")
    • The pylorus is connection to the stomach and duodenum.
    • Pyloric stenosis = hypertrophy of pylorus
    • Often occurs in newborns (few weeks old) and more common in males
    • The spleen originates from dorsal mesodermal tissue in a part of the stomach
    • Blood supply is similar to the stomach (celiac trunk)
    • The spleen is on the left side as a result of stomach rotation
    • Gastrosplenic(gastrolienal) ligament carries short gastric, left gastroepiploic vessels
    • The GI tract is comprised of many organs, including the mouth, esophagus, stomach, small intestine, large intestine, rectum, and anus, with corresponding regions of the GI tract
    • Abdominal CT scans are diagnostic images of the abdomen, which includes the liver, spleen, and gallbladder, and the GI tract
    • Intraperitoneal organs include stomach, appendix, liver, spleen, duodenum, jejunum, ileum, transverse colon, sigmoid colon and part of rectum and Tail of pancreas
    • Retroperitoneal organs include aorta, IVC, kidneys, small intestine: 2nd/3rd portions duodenum and colon: ascending/descending, part of rectum and Pancreas: Head, body
    • Retroperitoneal bleeding is often complication of surgical procedures
    • The peritoneal cavity is divided into greater and lesser sacs
    • The greater sac encompasses entire width of abdomen from diaphragm to pelvic floor
    • The lesser sac is behind liver, stomach and lesser omentum
    • In addition to the greater and lesser sacs, there is an epiploic foramen that connects the two sacs
    • The dentate or anocutaneous line is a part of the anal canal
    • The superior rectal artery is a branch of the inferior mesenteric artery
    • Venous drainage of superior rectal vein → inferior mesenteric vein → portal system
    • Lymph drainage of superior rectal vein → internal iliac nodes
    • Visceral innervation is present above the pectinate line; no pain
    • Internal hemorrhoids, adenocarcinoma; are common disorders above the pectinate line; rare form of anal cancer
    • Hindgut and ectoderm meet to form anus; absence of anal opening = imperforate anus; commonly associated with GU malformations (e.g., renal agenesis, bladder exstrophy)
    • The celiac trunk supplies organs of the foregut including the esophagus, stomach, liver, gallbladder, spleen, part of the duodenum, and pancreas
    • The superior mesenteric artery (SMA) supplies the midgut from the distal duodenum, jejunum, ileum, cecum, appendix, ascending colon, and first two-thirds of the transverse colon
    • The inferior mesenteric artery (IMA) supplies the hindgut from the last one-third of transverse colon to descending, sigmoid, and part of the rectum
    • The liver receives blood from the portal vein (about 80%) and the hepatic artery (about 20%)
    • Hepatic veins carry processed blood away from the liver, and the bile duct carries the bile produced by the liver away
    • Liver zones include zone I (periportal), Zone II (mid zone), Zone III (centrilobular).
    • Zone I is affected by viral hepatitis first, whereas ZOne III is the furthest from the blood supply and most vulnerable to ischemia
    • Fatty accumulation in Alcoholic Liver Disease usually begins in zone III
    • High concentration P450 enzymes in hepatocytes of liver zone III
    • The pancreas is an exocrine organ that produces secretions that aid in digestion (fluid: bicarb, water, electrolytes) and digestive enzymes
    • Two buds from foregut (dorsal and ventral) form the pancreas.
    • Ventral bud contributes to head, uncinate process and Main pancreatic duct
    • Dorsal bud contributes to rest of pancreas including head, body, tail and accessory duct
    • The pancreas is secondarily retroperitoneal, and it initially forms intraperitoneal and then fuses to the posterior wall, becoming retroperitoneal
    • Annular pancreas is a congenital anomaly
    • Ventral bud pieces remain separate (accessory dorsal duct) leading to pancreas divisum
    • Three major salivary glands including parotid, submandibular, and sublingual glands, throughout the mouth
    • Saliva is mostly water, mucin, glycoproteins; lubricates food and binds bacteria; IgA, lysozymes, lactoferrin
    • Salivary fluid is produced by acinar cells and modified by ductal cells
    • Initial fluid in saliva is isotonic (similar to plasma), but ductal cells remove Na, Cl and secrete K, HCO3-
    • Saliva becomes hypotonic as a result of the above process
    • Composition of saliva varies with flow rate, and closer to isotonic with plasma at higher flow rates
    • Aldosterone ↑ Na absorption and ↑ K secretion which acts on salivary glands similar to kidneys
    • Saliva is regulated by both sympathetic and parasympathetic systems, not gastrointestinal hormones
    • Sympathetic effect is smaller than parasympathetic effect
    • Muscarinic receptors (M1 and M3) are important for increase saliva production
    • Muscarinic antagonists can cause dry mouth
    • Pilocarpine used in Sjogren's syndrome increases saliva production
    • Sialolithiasis (salivary duct stones) is an obstruction of salivary flow leading to pain and swelling of the salivary glands
    • Sialadenitis = inflammation of the salivary gland
    • Usually secondary to obstructing stone.
    • Mumps is a viral infection of the parotid glands.
    • Swollen parotid glands are a key feature; often bilateral
    • Salivary tumors present in the parotid gland , most are benign; mobile (not invading nerves) and painless.
    • Pleomorphic adenoma; benign mixed tumor=Most common salivary gland tumor
    • Risk factors for Pleomorphic adenoma include prior radiation
    • Warthin tumors= Second most common salivary tumor; located in the parotid gland. Smoking is a key risk factor.
    • Key histological finding is cysts filled with fluid surrounded by lymphoid infiltrate
    • Mucoepidermoid carcinomas are most common malignant salivary tumors, sometimes invade facial nerve, and may cause pain.
    • It is characterized with squamous, mucous and hybrid cells
    • Hernias are protrusion of organ through the cavity wall.
    • Common in inguinal canal, esophagus, or umbilicus
    • Femoral vessels include nerve, artery, and vein that run lateral to medial; venous to penis
    • Femoral sheath = tunnel between femoral artery/vein and femoral ring
    • Hemorrhoids are engorged veins in rectum, occur in portal hypertension.
    • Umbilicus contains paraumbilical vein
    • Esophageal varices result from dilated submucosal veins, commonly occurring in portal hypertension.
    • Mallory-Weiss Syndrome = damage to esophageal mucosa at GE junction causing painful hematemesis
    • Boerhaave syndrome = transmural rupture of esophagus, due to severe chronic vomiting or retching
    • Esophageal webs, are growths or folds of tissue obstructing food passage
    • Schatzki ring = most common cause of dysphagia to solids; in the squamocolumnar junction
    • Plummer-Vinson Syndrome=triad of conditions; iron deficiency anemia; beefy red tongue and esophageal web. Common in middle-aged, white women
    • Zenker's diverticulum= uncommon disease of the hypopharynx in Killian's triangle
    • Usually result from chronic swallowing issues.
    • Viral hepatitis= Hep A,B,C,D,E which are very high AST/ALT (>1000), Hyperbilirubinemia and Jaundice, and may have hypoglycemia, abnormal PT/PTT, low albumin. Diagnosed with viral antibody test
    • Autoimmune Hepatitis= autoinflammatory disease of liver; more common in women in 40s/50s.
    • Symptoms may range from asymptomatic acute liver disease → cirrhosis.
    • Anti-nuclear antibodies and/or Anti-smooth muscle antibodies typical
    • Treatment is steroid and immunosuppressants
    • Tylenol overdose =Acetaminophen, Paracetamol, APAP = high AST/ALT (1000s)
    • Treatment = Activated charcoal may prevent absorption, N-acetylcysteine is treatment of choice
    • Shock/Ischemic Hepatitis= diffuse liver injury from hypoperfusion
    • Symptoms may include abdominal pain, markedly elevated AST/ALT, and is usually self-limited.
    • Zone 3 necrosis is typically seen in pathology
    • Cirrhosis is irreversible end-stage liver disease with many underlying causes = Viral Hep. B, C, Chronic alcohol use and non-alcoholic fatty liver disease (NAFLD)
    • Cirrhosis is characterized by shrunken liver, liver tissue replaces fibrosis, smoother liver surface replaced by nodules
    • Hyperammonemia, jaundice, hypoalbuminemia, coagulopathy, and elevated estrogen are clinical features in cirrhosis
    • Treatment for hyperammonemia may include low protein diet or Lactulose which neutralizes gastric acid
    • Portal hypertension is high pressure in portal vein due to cirrhosis, and blood flows portal vein → liver → hepatic vein.
    • Venous collaterals= high portal pressure opens connections between portal/systemic vessels.
    • Small bowel, Rectum, and Esophagus are common locations. These veins will engorge (swell) due to portal hypertension
    • The symptoms of hypersplenism are the result of increased spleen engorgement which leads to low portal HTN and low platelets counts. This is a rare cause of portal hypertension
    • Portal vein thrombosis is a rare cause of portal hypertension which may result in gastric varices and bleeding.
    • Ascites is accumulation of fluid in the peritoneal cavity due to liver disease and portal hypertension which may not be present if portal hypertension is absent
    • Serum Ascites Albumin Gradient (SAAG) >1.1g/dl if high pressure driving fluid into peritoneum = portal hypertension, SAAG <1.1 g/dL if serum and ascitic albumin levels are similar = malignancy (leaky vasculature).
    • Ascites treatment options are Sodium restriction and diuretics (Spironolactone being the drug of choice) and Large volume paracentesis
    • TIPS is a Transjugular Intrahepatic Portosystemic Shunt = creates a channel in the liver to connect portal vein to hepatic vein; treatment for portal hypertension
    • SBP (Spontaneous Bacterial Peritonitis)= Ascitic fluid infection; Usually E. Coli and Klebsiella
    • Treatment for SBP = 3rd generation cephalosporin (cefotaxime)
    • MELD Score is used to estimate 3-month mortality of liver disease. Factors measured include bilirubin level, creatinine level and INR
    • Child-Pugh is a classification that estimates risk/survival of liver disease; factors measured include encephalopathy, ascites, bilirubin, albumin and PT levels.
    • Gold standard for diagnosing cirrhosis = Liver biopsy; it is rarely required if there is sufficient history to clearly diagnose the disorder.
    • Stellate cells are perisinusoidal cells that store retinoids, which become activated in liver disease and secrete TG-B. Proliferate to produce fibrous tissue which is a major contributor to cirrhois
    • Hepatocellular carcinoma is most common primary liver tumor and is associated with chronic liver disease (Hepatitis B, C), alcoholic cirrhosis, Wilson’s disease, hemochromatosis, and alpha 1 anti-trypsin
    • Aspergillus = fungus that produces aflatoxin, which is a risk factor in hepatocellular carcinomas
    • Most colon cancers are adenocarcinomas.
    • Early colon cancer (noninvasive cancer) results in approximately 95% 5-year survival. Advanced cases have a 15% 5-year survival rate.
    • Colon cancers from right sided and left sided locations may result in different symptoms and causes
    • A colon polyp is a growth of tissue that protrudes into the lumen of the colon that may be pre-cancerous
    • Types of colon polyps include hyperplastic, adenomatous, juvenile, and others, with varied risk factors and characteristics
    • Risk factors in colon cancer include age > 50 years; smoking and diabetes and chronic pancreatitis
    • HNPCC= Hereditary Non-Polyposis Colorectal Cancer; Inherited mutation of DNA mismatch repair enzymes that leads to colon cancer via microsatellite instability
    • HNPCC= Risk is usually 80%, with the majority of these cancers starting without a pre-existing adenoma
    • Frequently leads to right sided tumors and increased risk of endometrial cancer
    • Cyclooxygenase-2 (COX-2): Has increased expression in colon cancer cells, and is commonly in left-sided cancers (more common)
    • Rationale for aspirin therapy; may reduce risk of colorectal cancer 20-40%. BUT, increases bleeding/ulcer risk. No clinical trial evidence supports its use in prevention
    • DCC gene is a tumor suppressor gene (chromosome 18q) and frequently mutated in advanced colorectal cancers
    • FAP = Familial Adenomatous Polyposis; Autosomal dominant disorder; germline mutation in APC gene (chromosome 5q)
    • FAP variants include; Gardner's syndrome- polyposis plus multiple extracolonic manifestations (benign bone growths, skin cysts, connective tissue growths, etc.); Turcot syndrome- polyposis plus brain tumors (mostly medulloblastomas and gliomas)
    • Dermatitis herpetiformis = skin condition associated with celiac disease; has herpes-like lesions from IgA deposition in dermal papillae
    • Typically resolves with a gluten-free diet
    • Tropical sprue = malabsorption due to unknown infectious agents; presents in tropics; Celiac is typically in duodenum, while tropical affects entire small bowel; Folate/B12 deficiency is common
    • Whipple's disease: infection with Tropheryma whipplei; involves the small intestine, joints, brain, and heart
    • 4 cardinal features = diarrhea (malabsorption of fats and sugars), abdominal pain, weight loss, and joint pains
    • Diagnosis = biopsies of small intestines; PAS-positive
    • Lactose intolerance is due to the insufficient lactase enzyme in the small intestine to break down lactose into monosaccharides (galactose and glucose). Secondary causes= mucosal injury/bacterial overgrowth/viral infections, and distal location. Symptoms of lactose intolerance is bloating, abdominal pain, and diarrhea after lactose-containing foods
    • Pancreatic insufficiency = results when there's a loss of pancreatic lipase and colipase secondary to cystic fibrosis or chronic pancreatitis which results in fat malabsorption, steatorrhea and deficiencies of fat soluble vitamins, and diabetes
    • Acute pancreatitis=acute inflammation of pancreas characterized by pain, nausea, vomiting, and spread of necrosis/hemorrhage
    • Rare findings = periumbilical or flank hemorrage; often in patients with rupturing ectopic pregnancy
    • Pathophysiology: blocked flow of enzymes, and activation of trypsin→ activates other enzymes→ autodigestion of pancreas
    • Diagnosis of acute pancreatitis is elevated serum pancreatic enzyme levels ; amylase and lipase are typically elevated and lipase is more specific in diagnosis
    • Diagnostic imaging for acute pancreatitis includes ultrasound and CT scans.
    • Common causes (often without recurrence except for alcohol and cystic fibrosis) = gallstones that result in abdominal symptoms and Obstruction of common bile duct from stones which leads to acute pancreatitis
    • Common treatment = NPO, IV fluids, and pain control
    • SIRS (Systemic Inflammatory Response Syndrome)= Clinical syndrome of dysregulated inflammation; possible complications from multiple causes (e.g., trauma, pancreatitis and sepsis)
    • Ranson's criteria is a method to assess pancreatitis using scoring system of physical exam findings at admission and 48 hours
    • Complications of acute pancreatitis = DIC (Disseminated Intravascular Coagulation- diffuse activation of clotting factors), ARDS (Acute lung injury), pseudocyst, fat necrosis, abscess, hypocalcemia, multiorgan failure
    • (All) Duodenal ulcers can lead to upper GI bleeding which cause hematemesis or melena(dark stools).

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    Gastroenterology Slides 2022 PDF

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    Test your knowledge on the embryonic layers involved in gastrointestinal tract development, chromosomal instability pathways, and associated conditions such as Familial Adenomatous Polyposis. This quiz covers important concepts in embryology and their connection to colon cancer and related syndromes.

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