GI Flashcards
Omphalocele vs Gastroschisis?
Omphalocele= Intestines protrude through umbilicus "Encased in viscera" Gastroschisis= Intestines protruding without Viscera
Child with abdominal content protruding through the umbilicus had what embryological failure?
Failure of Lateral Folds to Close
What is associated with failure of Caudal folds?
Bladder exstrophy
What causes Duodenal atresia vs Jejunal/ileal atresia?
Duodenal = Failure to Recanalize jejunal/Ileal= VASCULAR accident
Ulcer vs erosion?
Ulcer= Submucosa Erosion= Mucosa only
Layers of gut wall and contents/functions?
MSMS= Inside-> outside Mucosa= absorption Submucosa = Meissner's plexus for glands Muscularis= Auerbachs/ Myenteric plexus Serosa (intra) vs Adventitia (retro)
What part of GI has the slowest vs fastest Slow wave frequency?
Stomach = 3/min = Slowest Duodenum = 12/min= Fastest Ileum = 9/min
GI histology major landmarks: Duodenum Jejunum Ileum Colon
Duodenum= Brunners glands in Submucosa Jejunum= Plicae circularis Ileum = Peyers patches Colon = No villi + Lots of Goblet cells
Zone 1 vs Zone 3 of hepatic sinusoids?
Z1 = periportal (artery) + 1st site of Viral hepatitis
Z3 = Centralobular + Ischemia, Toxin, Alcoholic hepatitis
**P450 located in Zone 3 (ETOH injury more likely there)
Hormone released by cells in antrum and is upregulated by peptides, AAs (Trp, Phe), and vagus. PPI use also increases its secretion?
Gastrin –> H+ secretion + Mucosal growth + motility
What hormone increases GB & Pancreatic secretions and decreases gastric emptying in response to FA/ AAs in duodenum?
CCK –> Relaxes sphincter of ODDi / inc secretions from pancreas ALL through Muscarinic enhancement
How does CCK carry out its actions?
Enhances Muscarinic actions @ pancreas / GB
**NO direct actions
Enzyme released in response to Acid in duodenum has what actions?
Secretin => Inc Panc HCO3, Bile, and dec Gastric motility
**S cells of duodenum
hormone released from Duodenal K cells in response to oral glucose?
GIP –> Dec H+ secretion + Inc Insulin
Hormone that causes increased intestinal secretions and relaxation of sphincters. Located in PSNS ganglia and sphincters, GB, and small intestines?
Vasoactive intestinal peptide (VIP)
Signs and symptoms of a VIPoma?
WDHA
Watery Diarrea –> increases Intestinal secretions
Hypokalemia –> diarrhea caused
Achlorhydria –> Inhibits Acid release
Loss of what substance in the lower esophageal sphincter is implicated in Achalasia?
NO –> relaxes smooth muscle (esp LES)
What increases peristalsis during fasting states to activate the intestinal cleaning out actions?
Motilin –> Migratory Motor complex
What factors stimulate vs inhibit Gastric acid secretions?
Stimulate–> Histamine, ACh , Gastrin
Inhibit–> SS, GIP, PGs, Secretin
What is the MOA for gastric acid release by Vagal stimulation?
- Direct ACh innervation of Parietal cells
- ACh-> GRP -> Gastrin -> HCL release
- ACh -> GRP -> Gastrin -> ECL cells -> Histamine -> HCL
What is the primary way Vagus causes HCL release and how is this affected by Atropine?
Main way is Increased Histamine release from ECL
**Atropin ONLY blocks Direct ACh inn of Parietal cells but Cannot inhibit GRP-> Gastrin rel -> Histamine
Location within the stomach: Parietal cells Chief cells Gastrin cells Mucous cells
Parietal & Chief =-= BODY
Gastrin & Mucous == Pylorus/ antrum
Secondary messenger system for HCl release by ACh, Gastrin, and histamine?
ACh + Gastrin –> Gq receptors = IP3/Ca
Histamine (H2) –> Gs –> cAMP
**PGs + SS –> Gi –> dec cAMP
What happens in the Gastric veins in response to HCl release?
Alkaline tide
Pt with peptic ulcer dz or ZE syndrome is expected to have what cells hypertrophy?
Duodenal Submucosal Brunners glands==> Inc HCO3 release
Carbohydrates are absorbed in the GI tract how?
Monosaccharides
Glu + Galactose ==> Na dep SGLT-1
Fructose==> GLUT-5 (Na independent)
What is the purpose of the D-xylose test?
Differentiate btwn Mucosal or other causes of Malabsorption
Admin D-xylose => Inc in Urine mean Normal GI mucosa
**Same as B12 schilling test
Absorption of Fe, Folate, and B12 happen where?
Fe –> Duodenum
Folate–> Jejunum
B12–> Ileum
How is bile made water soluble in Liver?
Conjugated to Glycine or Taurine
**Bile is antimicrobial by disrupting cell membranes
Rate limiting step of Bile acid synthesis?
7 alpha Hydroxylase
Salivary gland tumors:
- Painless benign MIxed tumor + recurs frequently
- benign cystic + Germinal centers
- malignant painful (CN 7) Squamous component
- Pleomorphic adenoma (MC overall)
- Warthin’s tumor
- Mucoepidermoid carcinoma
Pt with labs showing HIgh LES opening pressure and uncoordinated peristalsis with Dysphagia for solids and liquids is @ high risk for?
Achalasia –> RF for SCC of Esophagus
- *Primary = Dec NO in LES
- *2nd –> Chagas
Esophagitis:
Pseudomembranes
Punched-out lesions
Linear ulcers
Candida= pseudomembrane HSV1 = Punched out lesions CMV= Linear ulcers
Lye ingestion and acid reflux are associated with?
Esophageal strictures
Pt with dysphagia for solids, erythematous oral cavity, and hypochromatic anemia?
Plummer Vinson syndrome
- Esophageal webs
- Glossitis
- Iron def anemia
Older male with Cardiac abnormality, joint pain, and CNS difficulties suffers from malabsorption. What is seen on biopsy of intestines?
Whipple’s ==> PAS+ Foamy macrophages
What antibodies, HLA, GI locations, and malignancy are associated with Celiac sprue?
- Anti- endomysial + tissue transglutaminase + gliadin
- HLA- DQ2 + DQ8
- Jejunum will Blunted villi
- T-cell lymphoma
Curling vs Cushing acute erosive ulcers?
Curling –> Burns victims (dec BF to gastric mucosa)
Cushing-> Head trauma = Inc Vagus-> HCl production
*NSAIDS + ETOH also cause Acute erosive ulcers
Chronic nonerosive ulcers:
Fundus/ body:
Antrum
Fundus/body=> Autoantibodies against parietal cells –> Acholorhydria + anemia
Antrum –> H pylori
55 yo male with edema, hypoalbuminemia, complains of abdominal pain. Biopsy of stomach shows Parietal cell atrophy and inc mucosal cells. Dx?
Menetriers disease –> Elevated TGF-alpha
Stomach cancer:
Intestinal type
Diffuse type
Intestinal–> Ass (h.pylori, AI gastritis, Nitrosamines) @ Lesser curvature as Ulcer with Raised margins
Diffuse–> H. pylori, Signet rings, linitis plastica
Gastric vs Duodenal ulcers?
Gastric-> Pain inc w. food (lose wght), Carcinoma risk, caused by dec Mucosal protection (NSAIDS, burns)
Duodenal–> Dec pain w. food (wgt Gain), dec mucosal protection + In HCL, Hypertrophy of Brunners glands
Crohns disease associations?
Disordered response to Bacteria
Ileum, Skip lesions, rectal sparing
Transmural, COBBLESTONE, creeping fat, fissures, fistulas
“STRING sign” on barium swallow/X-ray
Granulomas –> Th1
Migratory polyarthritis, Ankylosing spondylitis, Cancer
**Kidney stones, Erythema Nodosum
Rx: Steroids, Mxt, infliximab, adalimumab
UC associations?
Autoimmune Continuous + RECTUM Psuedopolyps "LEAD pipe" sign on imaging Crypt abscess --> Th2 Sclerosing Cholangitis, TOXIC megacolon, Cancer Pyoderma Gangernosum, Rx: Sulfasalazine, 6-MP, Infliximab
Middle aged women complains of abdominal pain that “improves with defecation” and changes in stool frequency. What changed in her life?
IBS –> JOB, school, promotion
Appendicitis cause in Children vs Adults?
Child –> Lymphoid hyperplasia post Viral infection
Adult –> Fecalith Obstruction
Diverticulosis characteristics?
False –> Mucosa + submucosa
Inc pressure (constipation) + wall weakness + low fiber
**HEMATOCHEZIA
Sigmoid colon
65 yo with LLQ pain, fever, and leukocytosis. Stool occult+?
Diverticulitis
2 yo child with recent history of conjunctivitis and URTi comes in with abdominal pain and bloody “jelly” covered stools?
Intussusception –> MC post Adenovirus and w. “current jelly” stool
Dx/Rx: barium dye
Infant with Down syndrome is brought in with bilious vomiting. X-ray shows “double bubble” sign. What embryological event caused this?
Duodenal Atresia–> Failure of Recanalization
Elderly man with severe pain @ the LUQ. Pain is worse with food and has caused him to lose wght. Lab tests show no abnormalities?
Ischemic colitis –> @ splenic flexure
Pt complains of abdominal pain and constipation several months after an abdominal surgery. MCC?
Adhesions
Pt with hematochezia and found to have tortuous dilated vessels in the cecum?
Angiodysplasia
Precancerous adenomatous polyps have a risk of malignancy associated with?
VILLOUS
inc Size
Dysplasia
MCC of non-neoplastic polyps in the sigmoid colon?
Hyperplastic
Juvenile polyps are?
80% in RECTUM
NO malignant potential
Child with abdominal pain and hyperpigmented lesions around his lips and in his oral mucosa?
Peutz-Jeghers –> non-Malignant Hamartomas
Gardners syndrome associations?
FAP
Osseous & soft tissue tumors
Congenital Hypertrophy of Retinal pigment epithelium
Pt with a hx of colon cancer recently developed a headache and seizures?
Turcot syndrome = FAP + CNS tumor
What are the 2 molecular mechanisms for CRC?
- Microsatellite instability–> DNA mismatch repair gene mutation (HNPCC) + sporadic accumulation of mutations
- APC/Beta Catenin (chromasomal instability)
APC–> KRAS –> p53
Mechanism of Reyes syndrome damage?
Aspirin metabolites dec Beta Oxidation by reversibly inhibiting MITOCHONDRIAL enzymes
Cavernous hemangioma?
MC benign tumor of Liver
Biopsy is CI due to risk of Hemorrhage
Hepatic adenoma?
benign liver tumor
OCP + steroids
Regresses if OCP/steroid discontinued
Endothelial cell tumor associated with Polyvinyl chloride in the liver?
Angiosarcoma
What is the cause of physiological jaundice of new born?
Immature UDP-GT
pt with absent UDP-GT causing jaundice, kernicterus can be treated with what?
Crigler- Najjar syndrome
Type 1 –> Plasmapheresis + Phototherapy
Type 2–> Phenobarbital (inc Liver enzyme synthesis)
Conjugated bilirubinemia and hepatocytes with “epinephrine metabolite” granules. What is the defect?
Dubin-Johnson ==> defect Liver excretion of Bilirubin into bile duct system
Characteristics of Wilsons disease?
Ceruloplasmin dec Cirrhosis --> HCC Copper accumulation Corneal deposits (Keyser Fleischer) Hemolytic anemia Basal ganglia degeneration Asterixis Dementia, Dyskinesia, Dysarthria AR ATP7B gene mutation (Cu transporter) Rx: Penicillamine
Characteristics of Hemochromatosis?
Triad: Cirrhosis, DM, bronze skin
CHF (dilated CM) , testicular atrophy, HCC
Inc Ferritin/Fe/Transferrin sat BUT dec TIBC
Set off Metal detectors
C282Y HFE gene mutation
Rx: phlebotomy, Deferasirox, Deferoxamine
Pt with a Hx of abdominal pain and bloody diarrhea develops pruritis, jaundice and dark urine. What is most likely to be seen on biopsy, imaging, and labs?
UC –> Primary Sclerosing Cholangitis
biopsy –> Onion skin bile duct fibrosis
Image–> Beading of bile duct
Labs–> Cong bilirubinemia + Hyperagammaglobulinemia
33 yo women with Hx of RA and celiac disease develops itch yellow skin and hepatosplenomegaly. What is the Most likely cause and characteristics?
Primary Biliary Cirrhosis
- Anti-Mitochondrial antibodies
- Granulomas
Cholesterol stones are associated with?
Radiolucency 4 Fs (Female, Fat, Fertile, Forty) Crohns/ CF Clofibrates Estorgen **Rapid wght Loss** Native Americans
Pigmented stones are?
Radiopaque
Black = hemolysis
brown = Infection
Common causes of Acute pancreatitis?
Gallstone ETOH Hyper TG >1000 Mumps Scorpion sting Steroids
Complications associated with Acute pancreatitis?
DIC, ARDS
Fat necrosis –> Saponification –> Hypocalcemia
Pseudcyst –> Line by granulation tissue–> Rupture–> Hemorrhage
Pancreatic adenocarcinoma associations?
Prognosis 6 mo or less CA-19-9 Tobacco (not EtOH) Migratory thrombophlebitis (Trousseaus's syndrome) Obstructive painless jaundice Palpable GB (Courvoiser's sign)
