Pathology of small bowel Flashcards
what are plicae circularis
mucosal folds of the small bowel
what is te ligament of Treitz
a thin band of tissue (peritoneum) that connects and supports the end of the duodenum and beginning of the jejunum in the small intestine
what is the ampulla of vater
in which part of the small bowel is B12 absorbed
terminal ileum
where is iron/folate absorbed
duodenum + proximal jejunum
name the 4 histological layers of the small bowel
Mucosa
submucosa
muscularis propria
serosa
name the 3 types of structures/cells in the mucosa and their function
- Villi - location for digestion and absorption of nutrients from food (into columnar cells)
- Crypts - secrete ions, water, immunoglobulins and antimicrobial peptides into the lumen
- mucous - protects epithelium and promotes nutrient absorption
describe coeliac disease
- immune mediated disroder
- triggered by ingestion of gluten
Clinical presentation of Coeliac disease
Diarrhoea, bloating, fatigue, anaemia, vitamin malabsorption
Infants/children: irritability, abdominal distension, anorexia, diarrhoea, failure to thrive, weight loss, muscle wasting
Dermatitis herpetiformis = itchy, blistering skin lesions 10% of patients with coeliac
Endoscopy: normal/attenuated/flat mucosal surface
Increased risk of malignancy – enteropathy associated T cell lymphoma
name the skin manifestation of coeliac disease
Dermatitis Herpetiformis
IgA antibody deposits in the skin and a subsequent inflammatory reaction
autoimmune attack triggered by gluten
epithelial cells in small bowel are called
enterocytes
component of gluten which is toxic
gliadin
enzyme involved in gluten processing
tissue tranglutaminase (tTG)
how is the absorptive capacity of the enterocytes reduced by coeliac diseasae
Loss in villous height (flat, no test tubes)
Intra-epithelial lymphocytes
Gliadin (component of gluten) – suspected toxic agent
Triggers an abnormal immune reaction
Activation/proliferation of T lymphocytes
Damages enterocytes (epithelial cells in small bowel) and reduces absorptive capacity
adrenaline is a vasoconstrictive drug. true or false
true
causes of intestinal hypoperfusion
- cardiac failure
- shock
- dehydration
- vasoconstrictive drugs
celiac axis is
proximal duodenum
celiac plexus is
causes of small bowel ischaemia
SMA supplies the entire small bowel except the proximal duodenum (celiac axis)
- obstruction of mesenteric vessels (Acute/chronic)
- acute = thrombosis; atherosclerosis, vasculitis/embolism
- embolism: origin from atheromas in aorta
- mesenteric venous thrombosis - hypercoagulability, neoplasia, cirrhosis, trauma, compression of portal drainage
- intestinal hypoperfusion due to cardiac failure, shock, dehydration or vasoconstrictive drugs e.g. adrenaline
causes of mesenteric venous thrombosis -
hypercoagulability, neoplasia, cirrhosis, trauma, compression of portal drainage
diagnosis of MVT (mesenteric venous thrombosis)
CT Angiography (shows thrombus in mesenteric veins)
- D dimer levels (elevated in thrombotic levels)
- Coagulation tests (PT, aPTT, fibrinogen levels)
- cancer workup (if MVT is an unexplained first-time clot)
Prothrombin time (PT) is a blood test that measures the time it takes for the liquid portion (plasma) of your blood to clot. It measures the function of a part of the clotting system
type of cell death following ischaemia
coagulative necrosis
