small intestine Flashcards
causes for duodenal ulcers
H. pylori (90%)
Zollinger-Ellison Syndrome (gastrinoma in pancreas): consider if RECURRENT after tx with PPI, check gastrin level
BILIOUS vomiting
“double bubble sign”
duodenal atresia (no canalazation of duodenum = blind pouch) distention of stomach in front of pylorus + distention of duodenum pouch
associated with duodenal atresia
down syndrome
imaging evaluation of patient with jaundice
endoscopic retrograde cholangiopancreatogram (ERCP)
esophagus → stomach → duodeunum → inject dye in ampulla of vater → visualize biliary tree + pancreatic duct
located in duodenal submucosa
brunner gland
hypertrophied with duodenal ulcers
brunner glands
prokinetic agents
↑Ach (parasympathetic), ↑5HT (carcinoid syndrome - produces vasoactive amines), ↓D2
cholinergic agoinst (bethanechol)
acetylcholinesterase inhibitors (neostigmine)
metoclopromide: stimulate 5HT4, inhibit D2
macrolide: stimulate smooth muscle motilin receptors
no peristalsis - blood diverted to more important areas of body
cause: post-op, stroke, septic shock, ICU
treatment: prokinetic agents
intestinal ileus
↑ 5HT causes
diarrhea (seen in carcinoid syndrome)
enterocyte characteristics
villi: absorption
secrete digestive enzymes
Crypts of Lieberkuhn
between villi of enterocytes
glands that secrete digestive enzymes
iron absorption
duodenum
folate absorption
duodenum + jejunum
B12 absorption
terminal ileum
iron deficiency anemia due to malabsorption
antacids, some antibiotics (quinolones, tetracycline): iron absorption occurs in acidic environment
gastric bypass surgery: bypass duodenum
causes of folate deficiency
poor nutrition: alcoholism
infant fed exclusively goat’s milk
infant fed exclusively with goat’s milk
folate deficiency
cause of B12 deficiency (megaloblastic anemia)
no terminal ileum
malnutrition
↓ absorption in terminal ileum
pernicious anemia: autoimmune destruction of gastric parietal cells (no IF)
AR
lack of apo-B leading to defective chylomicron assembly → chylomicron doesn’t leave enterocyte → enterocytes stop fat absorption
abetalipoproteinemia
apo-B48 is marker on chylomicrons
allows chylomicron to leave enterocyte
steatorrhea (malabsorption of ADEK) failure to thrive (first few months of life)
ataxia
acanthocytes: star RBCs
abetalipoproteinemia
disaccharidase deficiency
lactase breaks lactose → glucose + galactose
when not broken down: lactose is metabolized by bacteria in colon → fermentation →
bloating
cramping
diarrhea
lactase deficiency
lactase located in tips of microvilli - can be damaged in
gastroenteritis - blunts microvilli
temporary lactase deficiency
likely infectious cause
affects ENTIRE small intestine (vs celiac disease only in proximal small bowel)
tropical sprue
complications of tropical sprue
vitamin deficiencies
megaloblastic anemia
treatment of tropical sprue
antibiotics (doesn’t improve with gluten-free diet)
caused by tropheryma whipplei (G+)
whipple disease
older white male: weight loss diarrhea fever LAD hyperpigmentation cardiac sx arthritis neruo sx
whipple disease
PAS + foamy macrophages in intestinal lamina propria
whipple disease (t. whipplei inside macrophages)
treatment of whipple disease
penicillin, ampicillin, tetracycline
1-2 year long
nausea bloating vomiting diarrhea malabsorption aspirate of jejunum: excessive bacterial growth
bacterial overgrowth of small intestine
risk factor for bacterial overgrowth
dysmotility fistula diverticula illeocecal valve resection gastroenteritis PPIs
complication of: chronic pancreatitis cystic fibrosis gallstones cancer
pancreatic insufficiency
steatorrhea (fat malabsorption - ADEK vitamines)
pancreatic insufficiency
small intestinal mucosa laden with distended macrophages in lamina propria
whipple disease
defect in chylomicron exportation
abetalipoproteinemia
chronic abdominal pain + altered bowel habits
ab pain: crampy, variable intensity, IMPROVES with defecation
bowel habits: diarrhea, constipation, alternating diarrhea and constipation
other GI sx: GERD, dysphagia, early satiety, nausea, chest pain
non-GI sx: urinary frequency/urgency, dysmenorrhea, dsypareunia, fibromyalgia (depression too)
irritable bowel syndrome
symptoms NOT associated with IBS!!
rectal bleeding nocturnal ab pain weight loss anemia elevated inflammatory markers electrolyte abnormalities
treatment of IBS
avoid lactose or gluten fiber supplement antispasmodics: dicyclomine, hyoscyamine antidepressants: TCA, SSRI guanylate cyclase agonist: IBS with constipation
most common congenital anomoly in GI tract
Meckel diverticulum
incomplete obliteration vitelline duct
Meckel diverticulum
Meckel diverticulum
diagnosis of Meckel diverticulum
Meckel scan: look for ectopic gastric mucosa (pancreatic epithelium may also be present)
most common abdominal emergency in kids
intussusception
telescoping of bowel into DISTAL segment (near ileocecal junction - small bowel into cecum)
intussusception
complications of:
adenovirus
Meckel diverticulum
intussusception (but usually idiopathic)
“currant jelly” stool
intussusception (bloody stool)
“bulls-eye” or “coil spring” on US
intussusception
common causes of small bowel obstruction
ABC Adhesions: surgical adhesions from previous surgery (75%) Bulge: hernia (second most common - inguinal hernia incarcerated (can't reduce) → infarction/strangulation) Cancer: tumors (metastatic colorectal cancer most common) less common: volvulus intussusception chron's disease gallstone - obstructs lumen of SB ileus bezoar bowel wall hematoma from trauma inflammatory stricture congenital malformation radiation enteritis
dilated bowel on ab xray
small bowel obstruction
gas builds up
> 3 days to pass meconium
meconium ileus
normal time that meconium is passed
within 3 days of birth
causes of meconium ileus
cystic fibrosis
hirschsprung disease
premature infant that received oral feeds too soon: bowel undergoes feeding intolerance ↑gastric residuals ab distention bloody stools perforation
necrotizing enterocolitis
abdominal xray shows:
dilated loops of bowel
paucity of gas
pneumatosis intestinalis (presence of gas in wall of intestine)
necrotizing enterocolitis
treatment of necrotizing enterocolitis
bowel rest by giving parental nutrition (IV food)
↓ blood flow to part of bowel
associated with atherosclerosis of celiac or mesentaric arteries
splenic flexure (watershed) is susceptible to injury
distal colon too
ischemic colitis
elderly
pain out of proportion to physical exam (no signs of appendicitis, cholecystitis)
WORSE with eating
weight loss
ischemic colitis
small vascular malformation in gut → bleed easily
common in elderly
usually cecum or ascending colon
unexplained GI bleeding + anemia
dx: colonoscopy to see bleeding, angiography will better show bleeding
angiodysplasia
neuroendocrine tumor that secretes SEROTONIN in appendix, ileum, rectum and lung
carcinoid syndrome
BFDR Bronchospasm Flushing Diarrhea Right sided murmur (deposits in R sided valves) + edema, ascites (all = Right sided heart disease)
carcinoid syndrome: cause by excess serotonin from carcinoid tumor
*symptoms only if tumor is outside of GI tract because liver metabolizes all the 5HT produced in colon (carcinoid tumor mets outside of GI or started in lung)
