Flashcards in GI 2 Deck (68)
What is the general cause of ischemic bowel disease?
Decreased intestinal blood flow
What is the most common type of ischemic bowel disease?
Acute intestinal ischemia
In acute intestinal ischemia, injuries can range from mucosal _______ to transmural bowel ________.
range from mucosal necrosis to transmural bowel infarction.
Ischemic bowel disease may occur if there is occlusion of one of three major vessels, where extensive ______ may occur unless the rich vascular anastomoses prevent ischemia.
infarction may occur unless collateral flow prevents it.
Which specific artery is most often occluded in the case of acute intestinal ischemia?
The superior mesenteric artery.
What are the three levels of severity of ischemic bowel disease? Which levels correspond to chronic occlusion and which levels correspond to acute artery occlusion?
1. Mucosal infarction
2. Mural infarction
3. Transmural infarction
Mucosal and mural are due to chronic OR acute hypoperfusion. Transmural is a result of acute occlusion of a major mesenteric artery.
Name six conditions that are predisposing for acute intestinal ischemia.
2. Aortic aneurysm
3. Hypercoagulable state
4. Oral contraceptive use
5. Embolization of cardiac vegetation (crap on valves)
6. Aortic atheroma (plaque)
Are cardiac failure, shock, dehydration, drugs that vasoconstrict, systemic vasculitides, portal hypertension, and mass effect from tumors examples of other conditions associated with bowel ischemia?
In ischemic bowel disease, the infarcted bowel is _______ and diffusely purple. Hemorrhage is seen in the submucosa, especially in ________ occlusions. Ischemic injury begins in the _______ and spreads ________. Within 18 to 24 hours there is a thin, fibrinous ________ over the serosa. The mucosal surface will show irregular white sloughs and the wall becomes thin and _______, and bubbles of gas may be present in the bowel wall and mesenteric veins.
infarcted bowel is edematous and diffusely purple.
hemorrhage seen in venous occlusions especially.
Ischemic injury begins in the mucosa and spreads outwards.
18-24 hours there is a thin, fibrinous exudate over the serosa.
Mucosal surface will show irregular white sloughs and the wall becomes thin and distended.
Name two complications from ischemic bowel disease.
1. Bacterial produce gangrene within 24 hours and can perforate the bowel.
2. Healing with granulation tissue and fibrosis with eventual stricture formation (narrowing) .
What is adynamic ileus?
When the bowel proximal to an infarcted area becomes clogged due to abnormal smooth muscle and peristalsis function.
What is celiac disease?
An autoimmune response to the ingestion of gluten that results in atrophy of the intestinal villi.
Celiac disease is characterized by generalized __________ and mucosal lesions.
What if someone has a positive response to taking gluten-containing foods out of their diet?
Then they probably have Celiac disease.
90% of patients with Celiac disease carry HLA____, HLA___, and _____.
HLA B8, HLA DR8, and DQ2
What specific protein in gluten is suspected of causing Celiac disease? What is the mechanism?
Gliadin interacts with the immune system, leading to the killing of enterocytes and damaging the mucosal epithelium --> loss of tight junctions and leaky intestines.
Name the cells that one would find in a section of bowel from a person with Celiac disease.
Increased CD8+ T cells.
Increased plasma cells, mast cells, eosinophils in the lamina propria but NOT in deeper layers.
Pseudomembranous colitis is an example of ________ enterocolitis in which the organism _________ proliferates following antibiotic use, releasing toxins in to the GI tract.
example of infectious enterocolitis in which C. difficile releases toxins into the GI tract.
Morphological changes of pseudomembranous colitis include the adhesion of a _________ mucus to the superficial mucosa, denuded surface epithelium and a dense infiltrate of _________ in the lamina propria. Superficially damaged crypts with released exudate resembles a ________.
fibrinosupprative mucus and infiltration of neutrophils in the lamina propria. Damaged crypts with released exudate looks like a volcano.
A herniation of the mucosa and submucosa through the muscular layers of the colon.
What type of factors are primarily responsible for causing diverticulosis? How was this figured out?
Environmental. We know this because the prevalence of the disease in different places is highly variable.
____% of people in western countries are affected by diverticulosis, and the prevalence of the disease _______ (increases or decreases) with age.
10%, prevalence increases with age
Describe a histologic cross section of a colon with diverticulosis in terms of how the layers are affected.
The mucosa, muscularis mucosae, and submucosa layers herneate through the muscularis externa layer.
Which section of the colon is affected by diverticulosis 90% of the time?
Sigmoid colon (distal)
Name the disease: A flask-like 1 cm out-pouching that extends through the muscularis externa and is retained by a serosal connective tissue.
What symptoms are typical of diverticulosis?
Trick question! It is usually asymptomatic.
Name the disease: Chronic, segmental, transmural inflammation of usually the distal small intestine (although can happen anywhere in the GI tract - particularly the right colon).
Which populations are predominantly affected by Crohn's disease?
Adolescents, young adults. Mostly Europeans. Especially high frequency amongst the Jewish pop. Slight female predominance.
Name four factors that are thought to predispose people to Crohn's disease.
1. Genetic: Family Hx of IBD, mutation of NOD2/CARD15 gene.
2. Immunologic: Chronic inflammation, messed up mucosal immune response, immunosuppression therapy.
3. Epithelial defects: Defective transport across epithelium.
4. Microbial: Not understood.