Gastrointestinal System Flashcards
What is the embryological derivation of the pancreas?
Foregut endoderm
Ventral bud –> pancreatic head, main duct, uncinate process
Dorsal bud –> pancreas body, tail, isthmus, accessory pancreatic duct
What is the embryological derivation of the spleen?
Mesoderm
What structures are retroperitoneal?
Adrenal glands
Kidneys
Ureters
Aorta and IVC
Duodenum (2nd thru 4th parts)
Pancreas (except tail)
Colon (descending and ascending)
Esophagus (lower 2/3)
Rectum (partially)
What is contained within the portal triad?
Proper hepatic artery
Portal vein
Common bile duct
Meissner vs. Auerbach plexus
Meissner plexus located in the submucosa
Auerbach/myenteric plexus located in the muscularis externa
Describes the hepatocyte zones
Blood flows from the portal vein and hepatic artery to the central vein
Zone 1 = periportal zone → affected first by viral hepatitis and ingested toxins
Zone 2 = intermediate zone
Zone 3 = pericentral/centrilobular zone → affected first by ischemia, contains P-450s, most sensitive to metabolic toxins, affected first by alcoholic hepatitis
Above vs. below pectinate/dentate line
Describe the different kinds of hernias
Umbilical hernia → defect at linea alba
Sliding hiatal hernia → GE junction is displaced superiorly forming “hourglass” stomach
Paraesophageal hernia → normal GE junction but fundus protrudes into thorax
Indirect inguinal hernia → enters deep inguinal ring lateral to inferior epigastric arteries 2/2 failure of obliteration of process vaginalis
Direct inguinal hernia → protrudes through Hesselbach’s triangle through a weakness in the transversalis fascia medial to the inferior epigastric arteries
Femoral hernia → protrudes below the inguinal ligament through the femoral canal lateral to pubic tubercle (more common in females)
Salivary tumors
Benign
Pleomorphic adenoma → chondromyxoid stroma and epithelium; often recurs after resection
Warthin tumor → cystic, germinal centers
Maliganant
Mucoepidermoid carcinoma → mucinous and squamous cells
Triad of Plummer-Vinson Syndrome
Dysphagia from esophageal webs
Iron deficiency anemia
Glossitis
Intestinal type gastric adenocarcinoma
A/w H. pylori infection, smoking, nitrosamines (smoked foods)
Ulcer with raised margins on the lesser curvature
May metastasize to Virchow node (left supraclavicular) or Sister Mary Joseph nodule (subcutaneous periumbilical)
Diffuse type gastric adenocarcinoma
NOT associated with H. pylori infection
Signet ring cells, thickeninc of stomach wall → linitis plastica
a/w metastasis to bilateral ovaries (Krunkenberg tumor)
What are the fat soluble vitamins?
Vitamins A, D, E, K
Gardner Syndrome
Familial adenomatous polyposis (AD mutation of APC) + osseous and soft tissue tumors, congenital hypertrophy of retinal pigment epithelium
Turcot Syndrome
Familiarl adenomatous polyposis (AD mutation of APC) + malignant CNS tumors
Hereditary nonpolyposis colorectal cancer (Lynch syndrome)
Autosomal dominant mutation in DNA mismatch repair genes a.k.a 3’ → 5’ exonucelases (microsatellite instability)
Always involved proximal colon
Adenoma-carcinoma sequence
- APC mutation increases risk for formation of polyp via decreased intercellular adhesion and increased proliferation
- K-ras mutation leads to formation of polyp via unregulated intracellular signal transduction
- p53 mutation and increased expression of COX allows for progression to carcinoma; reduced risk with aspirin
Histology of alcoholic liver disease
Steatosis (reversible) → lipid droplets in hepatocytes
Hepatitis → swelling and necrosis of hepatocytes with neutrophilic infiltration and Mallory bodies (intracytoplasmic eosinophilic inclusions)
Cirrhosis (irreversible) → sclerosis around central vein, regenerative nodules surrounded by fibrous septa
Liver disease associated with exposure to arsenic or vinyl chloride
Liver angiosarcoma, malignant tumor of endothelial cells
Liver disease associated with exposure to OCPs or anabolic steroids
Hepatic adenoma, benign tumor of hepatocytes
Wilson disease
Autosomal recessive defect in ATP7B gene (chromosome 13) → ↓ hepatic copper excretion and failure of copper to enter circulation as ceruloplamin
May manifest with hemolytic anemia, parkinsonian symptoms, asterixis, dementia, chorea, cirrhosis, hepatocellular carcinoma, Kayser-Fleischer rings (copper deposits in the cornea → visible on slit lamp exam), cystic degeneration of putamen and basal ganglia
Dx: ↓ ceruloplasmin
Tx: D-penicillamine, trientine (copper chelators)
Hemochromatosis
Excess body iron leading to deposition of hemosiderin in tissues and organ damage caused by HFE gene mutation or chronic transfusion therapy
Symptoms include cirrhosis, secondary diabetes mellitus, bronze skin, dilated cardiomyopathy → CHF, cardiac arrhythmias, testicular atrophy
Dx: ↑ ferritin, ↑ iron, ↓ TIBC → ↑ transferrin saturation
Tx: phlebotomy or chelation (deferasirox, deferoxamine)
Embryological formation of teeth
Ameloblasts from ectoderm produce enamel
Odontoblasts from neural crest produce dentin
Types of tongue papillae
Filiform (most common)
Fungiform
Circumvallate
Foliate (lateral aspects)
