March 29 - GI Flashcards
Pathogenesis of gallbladder cholesterol stones (3 causes)
- Bile supersaturation
- Decreased bile acids/decreased phospholipids to bind the insoluble cholesterol
- Gallbladder stasis
Pathogenesis of bilirubin stones
Unconj bili + Ca++ precipitate out to form radiopaque stones.
Gastric varices: portal HTN vs splenic vein thrombosis
Portal HTN: seen in cirrhosis, increased pressure in L gastric veins results in both gastric and esophageal varices
Splenic thrombosis: incresaes pressure in short gastrics causing varices in fundus only. Complication of chronic pancreatitis
Layers of stomach and ulcers vs erosions
Layers: mucosa, muscularis mucosa, submucosa, muscularis propria, serosa
Ulcers extend down into submucosa
Erosions do not fully extend through muscularis mucosa
C diff toxin
Inactivates Rho resulting in disruption of the actin cytoskeleton and disruption of tight junctions, increasing paracellular fluid secretion
Abetalipoproteinemia: pathology, pathophysiology
Pathology: Normal mucosal architecture with clear/foamy enterocytes due to accumulation of lipids in sm intestine villi. Red cells with abnormal membranes and thorny projections
Pathophysiology: AR mutation in MTP gene results in impaired formation of apoB-containing lipoproteins (VLDL and chylomicrons)
Watershed regions of colon
splenic flexure
rectosigmoid junction
Garlic odor
Seen in arsenic poisoning
Mallory weiss tear pathophys
Increased intrabdominal pressure during vomiting. Hiatal hernias a risk factor
Toxic megacolon
Inflammation causes release of inflammatory mediators and NO. This leads to colonic sm muscle paralysis and colonic distension
Diagnosis: x-ray showing multiple air fluid leels
Fidaxomicin
Macrocyclic antibiotic with poor oral absorption. Used for c diff
Blood supply: celiac trunk, SMA, and IMA
Celiac trunk: abdominal esophagus through upper duodenum, pancreas, liver, gallbladder, spleen
SMA: mid duodenum through 2/3 down transverse colon
IMA: distal 1/3 transferse colon to upper anus
Delta508 mutation
3 base deletion that results in abnormal folding of CFTR, preventing trafficking to right location
Infertility in CF
Due to absent vas deferens and decreased sperm transport despite normal production
Diphenoxylate
Opioid anti-diarrhea, decreases motility. Similar to loperamide
Imperforate anus
50% of time associated with GU abnormalities, esp urorectal, urovesical, and urovaginal fistulas
Hep B liver pathology
Hep B surface antigen accumulates in infected hepatocytes, appearing as finely granular, homegenous, dull eosinophilic inclusions
Acute liver injury: liver proteins
Elevated PT due to short half life of factor VII. Normal albumin due to its long half life
Polyethylene glycol
Osmotic laxative along with mag citrate
Systemic mastocytosis
Cloncal mast cell proliferation in bone marrow and skin. Caused by mutations in KIT. Increased histamine results in syncope, hypotension, flushing, and hives as well as increased gastrcic acid secretion and ulcers.
Retroperitoneal organs
SAD PUCKER:
- suprarenal (adrenal) glands
- aorta and IVC
- duodenum, except first part
- pancreas - head and body
- ureters and bladder
- colon- asc and desc
- kidneys
- esophagus
- rectum - mid to distal
Rifaximin
Non-absorbable antibiotic. Alters GI flora to decrease production of ammonia. Used to treat hepatic encephalopathy
Sudan stain
Looks for fat in the stool
Vibrio cholera vs C jejuni
Cholera grows on alkaline media
C jejuni grows at high temps
Cavernous hemangioma
Most common benign liver tumor
Hepatic adenoma
Associated with OCPs
Secrin
Released in response to acid in the duodenum. Increases bicarb release from submucosal glands and pancreas
CMV esophagitis
Seen in immunocompromised. Causes odynophagia, dysphagia. On endoscopty see linear shallow ulcerations. On biopsy, enlarged cells with intranuclear inclusion bodies
Metoclopramide
D2 antagonist used to treat gastroparesis. Increases resting tone, contractility, and LES tone. Increases motility
Cimetidine
H2 antagonist. ADRs: thrombocytopenia, CYP inhibition, gynecomastia
