Pathology small bowel Flashcards
What is the primary function of the small bowel?
Absorption
What are the functions of enterocytes and goblet cells?
Enterocytes = apsorption Goblet cells= secrete mucus
What is contained in the villi?
Lamina propria with immune cells
What is the blood supply to the small bowel?
All superior mesenteric artery ecept upper duodenum which is coeliac artery.
What are the 2 main causes of ischemia in the small bowel?
1) Mesenteric arterial occlusion
2) Non occlusive perfusion insufficieny
What are the 2 causes of mesenteric arterial occlusion?
Atherosclerosis
Thromboembolism (ususlly from the heart)
What are the causes of non occlusive perfusion insufficiency?
1) Shock- in trauma and major haemorrage, blood supply to the bowel is cut off
2) Strangulation obstructing venous return (hernia or adhesion
3) Drugs cocaine causes vasospasm of smooth muscle in the superior mesenteric artery
4) Hyperviscosit
Acute ischemia of the small bowel is a surgical emergency. T or F?
True
Which part of the small bowel is most efffected by ischemia and why?
Mucosa- it is the most metabollically active part. Necrosis begins in the mucosa and spreads out. If it spreads through the muscle layer. Bowel rupture will result
The longer the period of hypoxia in the small bowel the greater the damage and the greater the likelihood f complications. T or F?
True
In no occlusive ischemia, when does most of the tissue damage occur?
After reperfusion
What is the difference between a mucosal, mural and transmural infarct?
Mucosal- only effecting the mucosa and will resolve to normal
Mural- affecting the mucosa submucosa and possibly some of the mucle layer- repair and organization with fibrous tissue
Transmural- Affecting all layers of the bowel wall and will result in gangrene and possible death
What are the possible outcomes for ischemia of the small bowel?
Resolution
Fibrosis, chronic ischemia, mesenteric angina , obstruction
Gangrene, perforation, peritonitis, sepsis and death
What is mesenteric angina?
Abdonimal pain due to iscemina following exercise or a large meal
What is Meckel’s Diverticulum?
Incomplete regression of vitello- intestinal duct.
Tubular structure, 2 inches long, 2 foot above the illeocecal valve in 2% of people.
Most people with Meckel’s Diverticulum are assymptomatic but how can it present?
Bleeding, perforation or diverticulitis which mimics appendicitis
Can the diverticulum develop gastric ulcers and why?
Yes because it can contain gastic mucosa
Why are tumours of the small bowel rare
Because there is continuous enterocyte shed- they only last 72 hours. Any mutations etc are swept away and lost before they can progress
What tumours can metastatise to the small bowel?
Ovary, colon, gastric
What are the primary tumours of the small bowel from most to least common. Therey are all rare
Lymphomas- non hodkins type (maltomas (B cell) or T cell lymphomas) Neuroendocrine tumours (slow growing, locally invasive, produce hormones => carcinoid syndrome (seratonin like substance) headaches, flushing and diarrhoea.) Carninomas (present late, mets in lymph nodes and liver.)
Which cancers are associated with chrons disease?
Carcinoma
Which cancers are associated with coeliacs disease?
T cell lymphoma
Carcinomas
What are the causes of appendicitis?
Unknown,
Faecoliths (faeces impacted on appendix), Lymphiod hyperplasia, paracites, and tumours
What are the characteristic tissue changes in appendicitis?
Acute inflammation -neutrophils (must involve the muscle coat
Mucosal ulceration
Serosal congestion
Pus in lumen
What are the complications of appendicitis?
Peritonitis, rupture, abscess, fistula, sepsis and liver abscess
What other diseases is coeliac disease associated with?
Type 1 diabetes, especially in children
Thyroid diseases and skin conditions (Dermatitis Herpetiformis)
What are the complications of coeliac disease?
Malabsorption esp fats => steatorrhea
Reduced intestinal hormone production => reduced pancreatic secretion and bile flow=> gall stones
Ulerative jejenoilleitis T cell lymphoma
Small bowel carcinoma
What are the effects of malabsorbtion?
Loss of weight
Anaemia (Fe, Vit B12, Folate)
Abnormal bloating, failure to thrive in children, vitamin deficiencies
