Rubin's Small Intestine Flashcards
The duodenum extends to the…
Ligament of Treitz
The mucosal epithelium is replaced every….
4-7 days
What are the 4 types of cells in the small intestinal crypts?
Paneth cells, goblet cells, endocrine cells, undifferentiated cells
“congenital failure of duodenum to canalize”
duodenal atresia
What is duodenal atresia associated with?
Down Syndrome
“spherical tubular structures attached to the alimentary tract that have smooth muscular walls and GI type epithelium”
Duplications
“outpouching of all 3 layers of the bowel wall”
Meckel Diverticulum
Why does meckel diverticulum occur?
failure of the vitelline duct to involute
What is the most common and clinically significant congenital anomaly of the small intestine?
Meckel Diverticulum
What is meconium ileus?
an early complication of CF, the thick stool of a newborn
“twisting of the bowel along its mesentary”
Volvulus
Where are volvulus’ located in elderly and young adults?
Elderly–> sigmoid
young adults–> cecum
“Transverse circular ulcers, circumferential “napkin ring” fibrosis strictures, caseous necrosis”
Intestinal tuberculosis
3 most common intestinal fungal infections?
Candida, histoplasma, mucor
“telescoping of proximal segment of bowel for forward into distal segment”
Intussusception
Most common cause of intussusception in children and in adults?
Children–> terminal ileum
Adults–> tumor
Most common cause of acute intestinal ischemia?
SMA occlusion
T/F: the small intestine is highly susceptible to ischemic injury
True
What are the 3 causes of acute intestinal ischemia?
Arterial occlusion, nonocclusive intestinal ischemia, mesenteric vein thrombosis
Most common cause of chronic intestinal ischemia?
Atherosclerotic narrowing
Mucosal infarction is due to…
marked HTN
Transmural infarction is due to…
thrombosis/ embolism of SMA or mesenteric vein
What are the clinical features of small bowel infarction?
Pain, bloody diarrhea, hypoactive bowel sounds
What two substances are preferentially absorbed by the distal small intestine?
bile salts and vit B12
What does supply of bile require?
normal liver function
Unobstructed bile flow
intact enterohepatic bile salt circulation
What causes luminal phase malabsorption?
insufficient bile acids
What cause insufficient bile acids?
Impaired excretion of bile
Bacterial overgrowth
Deficient bile salts
What causes intestinal phase malabsorption?
specific enzyme defects or impaired transport
“decreased function of lactose enzyme in brush border of enterocytes”
lactose intolerance
How does lactose intolerance present?
Abdominal distention
Diarrhea (because undigested lactose is osmotically active)
“Immune mediated damage of small bowel villi due to gluten exposure”
Celiac disease
Celiac disease is associated with which HLA types?
HLA- DQ2
HLA- DQ8
ANtibodies seen in celiac disease?
IgG anti- endomysial and anti- tisse transglutaminase antibodies
Which parts of the small intestine are most affected by celiac disease?
duodenum and proximal jejunum
Most pathogenic part of gluten?
Gliadin–> antibodies against it are generated
Which immune cells are predominant in celiac disease?
Increased CD8 T cells
Pathologic findings in celiac disease?
destruction of villi and brush border but increased depth of intestinal crypts
Differences in tropical sprue?
1- tropical region
2- seen after infectious diarrhea and responds to Abx
3- damage to jejunum and ileum
“antibodies to the gut epithelium, especially to enterocytes”
Autoimmune enteropathy
“systemic tissue damage characterized by macrophages loaded with tropheryma whippelii”
Whipple disease
What are the symptoms of Whipple disease?
arthritis, fatty stools, increased skin pigmentation, CNS problems, endocarditis
“AR deficiency of APO B-48 and B-100 that causes malabsorption”
abetalipoproteinemia
What is Milroy disease?
intestinal lypnagiectasia + peripheral lymphedema
“generalized malformation that causes malabsorption”
Congenital lymphangiectasia
Name the 3 benign tumors of the small intestin?
Adenomas
Peutz- Jeghers Syndrome
GIST
“AD inherited disorder, intestinal hamartomatous polyps and mucocutaenous melanin pigmentation”
Peutz- jeghers Syndrome
Mutation seen in Peutz- jeghers Syndrome?
inactivating mutation of LKB1 protein kinase
Where do adenocarcinomas mainly occur?
duodenum or jejunum
Where does adenocarcinoma begin?
In crypt epithelium
What is MALT?
Primary intestinal lymphoma
carcinoid tumors are associated with?
MEN1
“malignant prolferation of neuroendocrine cells with neurosecretory granules that are chromogranin (+)”
carcinoid tumor
What hormone do carciod tumors usually secrete?
Serotonin–> 5- HIAA is in the urine (it is a metabolite)
What are the symptoms of carcinoid syndrome?
bronchospasm, diarrhea, flushing skin, right sided valvular dibrosis
