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85 Cards in this Set
- Front
- Back
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What ist he normal villus to crypt hieght ratio?
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4-5:1
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What do the villi of the small intestine do?
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terminal digestion and absorption of food through columnar cells
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What do the crypts of the small intestine do?
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secrete ions and water, deliver IgA and antimicrobial peptides to the lumen, site of cell division
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Where do you see intestinal atresia most commonly?
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duodenum
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What is Meckel's?
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persistent vitelline duct on antimesenteric side of bowel
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What are the complications of Meckel's?
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intestinal bleeding, intussusception, incarceration, perforation
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What are the most common causes of malabsorption?
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pancreatic insufficiency, celiac disease, Crohns disease
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What causes malabsorption due to defective intraluminal solubility?
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pancreatic insufficiency
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What causes malabsorption due to mucosal cell abnormalities?
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disaccharidase deficiency
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What happens in pancreatic insufficiency?
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loss of enzymes to breakdown complex nutrients, bacteria use bile salts for metabolism, bacterial overgrowth diminishes intra-luminal supply of salts
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what happens with disaccharidase deficiency?
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can't digest milk or dairy
can be due to congenital or hereditary inborn errors of metabolism or secondary to viral or bacterial infections |
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What causes malabsorption due to reduction in intestinal surface?
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Celiac disease
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Waht happens in Celiac disease?
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toxic affect of gluten on mucosal epithelial cells
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What is the mechanism of Celiac disease?
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hypersensitive reaction to gliadin,
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What are the morphologic changes with Celiac Disease?
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flattening of villi, crypt hyperplaisa, increased intraepithelial lymphocytes
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What are the complications of Celiac disease?
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T-cell lymphoma, adenocarcinoma of the small intestine
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What causes malabsorption due to lymphatic obstruction?
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Whipple's, lymphoma, lymphangiectasia
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what is the morphology of Whipple's?
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expansion of lamina propria of small intestine by foamy macrophages, PAS positive, cause lymphatic obstruction and malabsorption
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What causes Whipple's?
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Tropheryma whippelii
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How does Whipple's manifest itself?
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multi-system disease with lymph nodes and GI tract, chronic and debilitating disease unless recognized
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Why does lymphoma interfere with absorption?
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interferes with effective transport of nutrients through lymphatics
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Why does TB interfere with absorption?
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obstruction of lymphatic transport
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What causes malabsorption due to iatrogenic causes?
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gastrectomy, radiation enteritis
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What infectious agents can cause malabsorption?
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Giardia, rotavirus, Norwalk, adenovirus
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What drugs cause malabsorption?
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cholestyramine, colchicine, para-aminosalicylic acid, cathartics, neomycin
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What happens with Giardia infection?
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many patients are asymptomatic, can get malabsorption because they coat the bowel
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What is the morphology of Giardia finection?
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trophozoites on luminal surface, not usually invasive, can see villous blunting and increased intraepithelial lymphocytes
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Where do you most commonly see adenomas?
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small intestine near the ampulla of Vater
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How do adenocarcinomas present?
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intestinal obstruction
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How do tumors near the ampulla present?
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obstructive jaundice
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Who gets small intestine adenocarcinomas?
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40-70 year olds, Crohns, tumors, alcohol, tobacco
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Where are most carcinoids?
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appendix
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What are carcinoid tumors in the small intestine like?
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multifocal, intra/submucosal, ta-yellow, small
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What do carcinoid tumors look like microscopically?
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islands, nests, trabeculae, sheets of monotonous with round nuclei, salt and pepper chromatin
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What do carcinoid tumors present with?
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intestinal obstruction
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From what do carcinoid tumors come?
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endocrine cells and generate bioactive compounds
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What is carcinoid syndrome?
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vasomotor distrubances, flushing, intestinal hypermotility, diarrhea, cough, wheezing, endocardial fibrosis
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What controls electrolyte production by the pancreas?
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secretin
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What controls enzyme production by the pancreas?
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cholecystokinin
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What enzymes does the pancreas produce?
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trypsin, chymotrypsin, amylase, lipase, pphospholipase, elastase, ribonuclease
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What is acute pancreatitis?
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sudden destruction of the pancreas caused by escape of activated pancreatic enzymes into the parenchyma
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What are the two causes of acute pancreatitis?
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biliary tract disease, alcoholism, trauma, iatrogenic
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What's the pathogenesis of acute pancreatitis?
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activation of pancreatic enzymes in the pancreatic parenchyma, activation of trypsin is key
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How does duct obstruction lead to pancreatitis?
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obstruction of duct, increased pressure in duct, activated enzymes leak back into the parenchyma
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How does acinar cell injury cause acute pancreatitis?
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injury to acinar cell results in release of proenzyme with activation in interstitium of pancreas
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How does derangement of intracellular transport cause acute pancreatitis?
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abnormal secretion of enzymes, packaged in lysosomes of pancreatic cells, activated by lysosomal hydrolases, results in release of activated enzymes in the cells
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What is the gross appearance of acute pancreatitis?
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necrosis, hemorrhage, chalky white fat necrosis on the surface
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What is the microscopic appearance of acute pancreatitis?
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acute inflammation, necrosis of pancreatic parenchyma, fat, mild to severe hemorrhage
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What are the complications of acute pancreatitis?
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liquefaction of pancreatic parenchyma, abscess formation, pseudocyst, hemorrhage, fat necoris, hypocalcemia, duodenal obstruction, systemic organ failure
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What can cause chronic pancreatitis?
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alcoholism, biliary tract disease, pancreas divisum, hyperlipidemia/hypercalcemia
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What is pancreas divisum?
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congenital anomaly, ventral and dorsal pancreatic buds do not fuse in the embryo, larger dorsal pancreas is narrow and stenotic
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What are the complications of chronic pancreatitis?
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duct obstruction, toxic metabolic, oxidative stress, necrosis-fibrosis
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What are the toxic metabolic complications of chronic pancreatitis?
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lipid accumulation, acinar cell loss, parenchymal fibrosis
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Why does necrosis fibrosis do to the pancreas?
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duct distortion, altered pancreatic duct flow, loss of pancreatic parenchyma and fibrosis
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What does chronic calcifying pancreatitis look like?
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repeated inflammation results in atrophy of parenchymal cells, fibrosis, calcification of the interstitium
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What is the clinical significance of chronic calcifying pancreatitis?
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can diagnose on x-ray
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What causes chronic calcifying pancreatitis?
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alcoholism
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What causes chronic obstructive pancreatitis?
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stenosis of sphincter of Oddi
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What happens in chronic obstructive pancreatitis?
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fibrosis, atrophy, chronic inflammation without calcification
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What are the complicaitons of chronic pancreatitis?
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DM, pancreatic insufficiency, pseudocyst, pancreatic carcinoma
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What are the complications of pancreatic insufficiency?
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malabsorption
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What are the signs of pancreatic insufficiency?
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loss of fat into the stool, edema due to protein loss
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What are the causes of pancreatic cancer?
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smoking, fatty diet, benzidine, chronic pancreatitis, DM
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What genes are associated with invasive pancreatic adenocarcinoma?
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K-ras, p16, SMAD4, p53
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What is the most frequently inactivated tumor suppressor gene?
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p16
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Where do most pancreatic cancers occur?
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head of the pancreas
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What do A cells in the islet make?
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glucagon
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What do B cells in the islet make?
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insulin
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What do D cells in the islet do?
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somatostatin
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What do pancreatic peptide cells in the islet do?
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make pancreatic peptide
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What do islet D1 cells do?
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VIP
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What do insulinomas look like?
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invovle adjacent structures, yellowish-tan, encapsulated
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What do insulinomas look like microscopically?
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nests of monotonous cells with round nuclei and salt and pepper chromatin
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What are the symptoms of insulinoma?
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Whipple's triad, insulin shock with fasting, low fasting BG, relief of symptoms with IV or oral glucose
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What does traveler's diarrhea present with?
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diarrhea, abdominal pain, marked fluid loss, electrolyte imbalance
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What are common bacterial causes of infective enterocolitis?
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e coli, salmonella, staph, campylobacteri, cholera, yersinia enterocolitica
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What are common viral causes of infective enterocolitis?
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norwalk virus, rotavirus
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What are common parasitic causes of infective enterocolitis?
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entameba histolytica, strongyloides, diphyllobothrium, trichinella
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What is the most common GI symptom of HIV?
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diarrhea due to infection
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What are common causes of diarrhea in AIDS patients?
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mycobacterium avium-intracellulare, CMV, herpes, adenovirus, crypto
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What is pseudomembranous colitis?
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formation of pseudomembranes on teh mucosa at the site of injury
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What causes pseudomembranous colitis?
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toxins from bacteria
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Who gets pseudomembranous colitis?
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long-term antibiotics, nosocomial infection
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What does pseudomembranous colitis look like grossly?
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firable flecks on the surface of the bowel
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What does pseudomembranous colitis look like microscopically?
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peudomembrane of fibrin/acute inflammatory cells overlying an area of superficial ulceration, adjacent mucosa is mostly spared
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