GIT - small and large intestines Flashcards
non-neoplastic conditions of small and large intestines
congenital - dont study
- meckel diverticulum
- hirschsprung
acquired:
- vascular disorders
- enterocolitis (inflammation of bowel tract)
- malabsorption
- idiopathic IBD** (IBD = inflammatory bowel disease)
- diverticular disease
- intestinal obstruction
IBD
+ pathogenesis (4)
+ who it affects more commonly
Chronic condition resulting from inappropriate mucosal immune activation
eg. crohn’s disease, ulcerative colitis**
- Caucasians at early adulthood
pathogenesis: combined effects
- alteration in host interaction w/ intestinal microbiota
- intestinal epithelial dysfunction
- mucosal immune response
- altered composition of gut microbiome
IBD causes
- Arterial thrombosis:
Atherosclerosis, vasculitis, hypercoagulable states - Arterial embolism:
Cardiac vegetations, aortic atheroembolism - Venous thrombosis (not common)
Hypercoagulable states, invasive neoplasms, trauma etc - Non-occlusive ischemia
Congestive cardiac failure, shock, dehydration, vasoconstrictive drugs - Volvulus/herniation/adhesions
-> intestinal obstruction
IBD presentation
+ treatment
gross features: loss clear sharp demarcation
looks black like a mushroom
treatment:
- immunosuppression
- probiotics, fecal microbial transplant
factors affecting IBD extent
- blood supply: celiac/ sup/inf mesentaric arteries
- what kind of occlusion
acute/ insidious (slowly increasing in size) - insidious more tolerable - depth of infarction ‘infiltrating’ the bowel wall: transumural/ mural/ mucosal
crohn’s disease
recurrent GRANULOMATOUS, FIBROSING inflammatory disorder
causes transmural chronic inflammation w/ deep, knife like ulcers
skip lesions
affects ileum + colon
effects of crohn’s disease
- formation of fistula - causes malabsorption
- narrowed bowel lumen
- peritonitis
- involvement of rectum: perianal abscesses and fistula - common
- potential malignancy
ulcerative colitis (UC)
no fibrosis and granulomas
mucosal inflammation w/ superficial, broad-based ulcers
diffused lesions
affects only rectum and distal colon (SPARES PROXIMAL COLON)**
depletion of goblet cells
presence of inflammatory pseudopolyps
toxic megacolon* - muscularis propia damaged by inflammation -> massive dilation and risk of perforation
systemic manifestations of UC
- Skin: Erythema nodosum
- Joints: Migratory polyarthritis, sacroilitis, ankylosing spondylitis
- Eye: Uveitis, conjunctivitis
- Liver: Primary sclerosing cholangitis
malabsorption
+ presentation
+ examples of malabsorption disorders
defective absorption of fats, vitamins, proteins, carbohydrates, electrolytes, minerals and water
presentation: chronic diarrhoea
- pancreatic insufficiency
- celiac disease
- crohn’s disease: inflammation of digestive tract
celiac disease
- morphology
- treatment
gluten sensitivity
treatment: gluten free diet for up to 2 yrs
morphology: immune response - increase in CD8+ lymphocytes, crypt hyperplasia, atrophy of villi
causes of infectious enterocolitis
- bacteria
E.coli
Salmonella, Shigella spp. – bloody diarrhea (dysentery)
Vibrio cholerae – preformed toxin, secretory diarrhea
Campylobacter jejuni - traveller’s diarrhea Mycobacteria - virus
Rotavirus, norovirus, enteric adenovirus
Herpes simplex virus (HSV)
Cytomegalovirus (CMV) - fungi
Candida
Pseudomembranous colitis
antibiotics associated:
antibiotics disrupt normal colonic microbial flora -> C.diff overgrowth -> colonic mucosal injury causes production of mucopurulent exudates -> inflammatory cells layer (pseudomembranes)
Pseudomembranous colitis
clinical presentation
diagnosis
Fever, leukocytosis (high WBC count), abdominal pain/cramps, watery diarrhea
diagnosis: detect C.diff
Intestinal TB
+ diagnostic method
involves ileocecal region
- ulcers are circumferential
thickening of walls w/ strictures
- regional lymphadenopathy (swelling of lymph nodes)
- Miliary spread
- Caseating granulomas: epithelioid histiocytes, langhan giant cells, central caseous necrosis
diagnosis:
Mycobacterium tuberculosis: Ziehl-Neelsen stain for acid-fast bacilli
