small intestine Flashcards
complications of refractory celiac dz despite gluten free diet
t cell lymphoma
SI adenocarcinoma
biological causes of malabsorption in viral, bacterial and parasitic gastroenteritis
terminal digestion and transepithelial transport
describe the pathogenesis of adhesions
- MC type of intestinal obstruction in the US
- peritoneal inflammation (congenital or acquired from surgery/trauma)–> adhesions/fibrous bridges–> entrapped viscera (internal herniation) –> obstruction , strangulation
complications of external herniation (visceral protrusion of GI tract )
incarceration, strangulation, and infarction
-impaired venous return–>stasis/edema–> enlarged hernia, permanent entrapment (incarceration) –> arterial/venous compromise (strangulation) –> infarction
what pathology is associated with lipid accumulation seen with red-o oil stain
abetalipoprotienima
biological causes of malabsorption in acetalipoproteinemia
transepithelial transport
biological causes of malabsorption in chronic pancreatitis, and cystic fibrosis
intraluminal digestion
AR DO presents in infants with inability to secrete triglyceride rice lipoproteins (APOB 48 and APOB 100) due to MTP mutation
abetalipoprotienima
- APOB48 makes chylomicrons
- APOB100 makes LDL VLDL
most common presentation of malabsorption
chronic diarrhea
others: wt loss, distention, borborygmi (rumbling), muscle wasting, steatorrhea
congenital lactase deficiency vs acquired
congenital: (rare) AR DO with explosive osmotic watery diarrhea, frothy stools, ab distention all on consumption of milk
acquired: decrease regulation of lactase gene common in native americans, african americans, chinese/ sx: ab fullness, osmotic diarrhea, gas on consumption of dairy
* may be TEMPORARY kind following infections with similar symptoms
4 types of diarrhea
- secretory - isotonic stool; persistent with fast
- osmotic- osm gap; decrease with fast
- malabsorptive- steatorrhea; decrease with fast
- exudative - purulent, bloody, persistent with fast
telescoping of proximal segment of bowel forward to distal segment associated with leading edge
intusseception
-can lead to obstruction and infarction
common causes and clinical manifestation of intestinal obstruction
common causes: hernias, adhesions, intussusception, volvulus
-clin man: ab pain, distension, vommitting, constipation
grows as a submucosal polyp like nodule and secretes serotonin in urine
midgut carcinoid tumor (jejunum/ileum)
- healthy liver = 5HIAA in urine and no carcinoid syndrome, heart disease
- liver metastais = bypass liver and serotonin is systemic causing right heart disease (R valve collagen/fibrosis –> PS or TR) and carcinoid syndrome (flushing, diarrhea, bronchospasm)
IPEX -X linked DO; causing FoxP3 mutation of CD4 T-reg cells resulting in antibodies to enterocyte goblet cells, parietal cells, or islet cells
*sx: severe persistent diarrhea and AI dz in young children
autoimmune enteropathy
biological causes of malabsorption in lactose def
terminal digestion
gross and histo of carcinoid tumor
gross: yellow/tan
histo: “salt n pepper” cytology
- dense core with neurosecreotry granules on EM (chromogranin A positive if midgut)
pathogenesis of celiac disease
deaminated gliadin by tissue transglutaminase (tTG) is presented to CD4+ T helper cells via MHC II; the T cells imitate damage
what is the most common cause of intussecpition in adults
tumor or mass
4 main biological causes of malabsorption
- defect intraluminal digestion
- defect terminal digestion
- defect transepithelial transport
- defect lymphatic transport of lipids
t/f
because lactase deficiency defect is biochemical a biopsy of the brush border will be normal
true
-where lactose is normally located
3 variables of severity of SI infarction
- duration
- artery associated
- severity of compromise
lab findings of celiac dz
IgA ab vs endymysion, tTG, and gliadin
*if IgA def then it is IgG type
what is the most common cause of intestinal obstruction in children under the age of 2 yo
intusseception
-due to lymphoid (peters patch) hyperplasia due to rotavirus infection at the terminal ileum –> cecum
biosy findings of celiac dz
flat vili, crypt hyperplasia, CD8 intraepithelial lymphocytes
*immune mediated damage of SI villi (most commonly the DUODENUM)
cause of a transmural vs mucosal SI infarct and associated sx
transmural- hypercoaguble state and thromboembolism of the SMA or thrombosis of mesenteric vein
mucosal- marked hypotension (possibly shock)
sx: ab pain, BLOODY diarrhea, decreased bowel sounds (paralytic ileus- might need surgery)
average size of midgut carcinoid tumor and what are it secretions
<3.5cm (but aggressive)
-secrete: serotonin, Substance P, and PYY
biological causes of malabsorption in celiac dz
transepithelial transport and terminal digestion
carcinoid tumor causes _____ if liver metastasis
chronic diarrhea
twisting of the bowel about its mesentery
volvulus
-can lead to obstruction and infarction
most common site of volvulus
elderly - sigmoid colon
young adult - cecum
extra GI sx of celiac dz
dermatitis herpetiformis, iron def anemia, apthous ulcers, short state,
MCC of malabsorption in the US
- pancreatic insufficiency
- celiac DZ
- Crohns (IBD)
neurosecretory granules in midgut carcinoid tumor are ______ positive
Chromogranin A + tumor cells
biological causes of malabsorption in whipple disease
lymphatic transport
sx of abetalipoprotienima
FTT, diarrhea, malabsorption, steatorrhea, absent plasma lipoproteins (VLDL and LDL)
-fat vitamin def = membrane defects seen as acanthocythic RED cells (BURR CELLs) seen on peripheral blood smear
biological causes of malabsorption in Crohns
intraluminal digestion, terminal digestion, transpithelial transport
