Rubin's Small Intestine Flashcards by Erin Allmer

The duodenum extends to the…

Ligament of Treitz

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The mucosal epithelium is replaced every….

4-7 days

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What are the 4 types of cells in the small intestinal crypts?

Paneth cells, goblet cells, endocrine cells, undifferentiated cells

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“congenital failure of duodenum to canalize”

duodenal atresia

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What is duodenal atresia associated with?

Down Syndrome

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“spherical tubular structures attached to the alimentary tract that have smooth muscular walls and GI type epithelium”

Duplications

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“outpouching of all 3 layers of the bowel wall”

Meckel Diverticulum

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Why does meckel diverticulum occur?

failure of the vitelline duct to involute

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What is the most common and clinically significant congenital anomaly of the small intestine?

Meckel Diverticulum

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What is meconium ileus?

an early complication of CF, the thick stool of a newborn

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“twisting of the bowel along its mesentary”

Volvulus

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Where are volvulus’ located in elderly and young adults?

Elderly–> sigmoid

young adults–> cecum

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“Transverse circular ulcers, circumferential “napkin ring” fibrosis strictures, caseous necrosis”

Intestinal tuberculosis

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3 most common intestinal fungal infections?

Candida, histoplasma, mucor

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“telescoping of proximal segment of bowel for forward into distal segment”

Intussusception

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Most common cause of intussusception in children and in adults?

Children–> terminal ileum

Adults–> tumor

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Most common cause of acute intestinal ischemia?

SMA occlusion

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T/F: the small intestine is highly susceptible to ischemic injury

True

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What are the 3 causes of acute intestinal ischemia?

Arterial occlusion, nonocclusive intestinal ischemia, mesenteric vein thrombosis

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Most common cause of chronic intestinal ischemia?

Atherosclerotic narrowing

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Mucosal infarction is due to…

marked HTN

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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