GI embryology Flashcards by nancy Gillcrist

foregut, midgut and hindgut divisions

foregut - pharynx to duodenum
midgut - duodenum to proximal 2/3 colon
hindgut - distal 1/3 colon to anal canal

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foregut rotation

90 degrees clockwise

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failure of lateral fold closure causes

gastroschisis or amphalocele

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duodenal atresia due to…

failure to recanalize (trisomy 21)

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jejunal, ileal, or colon atresia due to

vascular accident

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midgut development

6th week it herniates through the umbilical ring
10th week returns to abd cavity and rotates around the SMA
=270 degree couterclockwise turn (view from below)
90 during herniation and 180 as it goes back

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gastroschisis

extrusion of abd contents through abd folds NOT covered by peritoneum

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omphalocele

persistence of herniation into umbilical cord; IS sealed by peritoneum (not incontact with amniotic fluid)

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EA with distal TEF

drooling, choking and vomiting with first feeding
TEF allows air to enter stomach visible on CXR
cannot pass a nasogastric tube into stomach!

presents with polyhydramnios

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isolated EA CXR

CXR shows gassless abdomen

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congential pyloric stenosis

hypertrophy of pylorus causes obstruction

palpable olive mass in epigastric region and nonbilious projectile vomiting at 2-6 weeks old

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achalasia

failure of LES to relax

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oligohydramnios vs poly hydramnios

oligo - too little amniotic fluid, decreased volume

poly - too much; fetus isnt swallowing

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in pharyngeal gut, lining is derived from?

cartilage, muscles, and nerves from?

endoderm

pharyngeal arches

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in for, mid, and hind guts,
epithelial lining is from?
muscles and CT from?
enteric nervous system from?

endoderm
splanchic mesoderm
neural crest

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gut tube is suspended by

dorsal mesentery

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midgut is temporarily connected to yolk sac by____

vitelline duct

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what factor regulates epithelial-mesenchyme interactions?

SHH (sonic hedgehog)

SHH induces the creation of

HOX which diactates the head to tail regions

branches of aorta to supply
foregut
midgut
hind gut

fg = celiac
mg = Superior mesenteric
hg = inferior mesenteric

foregut boundaries

oropharyngeal membrane to the respiratory diverticulum

LARP

stomach development

left anterior, right posterior

development of stomach curvatures

dorsal side grows faster –> lesser and greater curvatures

LARP

retroperitoneal organs

SAD PUCKER
supra adrenal glands
aorta/ivc
duodenum (2nd and 3rd)
pancreas (except tail)
ureters
colon (ascending and descencing)
kidneys
esophagus 
rectum

allantois

During the third week of development, the allantois protrudes into the area of the urogenital sinus. Between the 5th and 7th week of development, the allantois will become the urachus, a duct between the bladder and the yolk sac. A patent allantois can result in urachal cyst.

improper fixation of mesentery -->

volvulus

fecal discharge at umbilicus is due to

vitelline fistula meckels diverticulum does not connect with outside; blunt outpouch that is connected to umbilicus internally

hirschsprungs disease

aganglionic megacolon absence of enteric ganglia in bowel wall due to defect in neural crest migration causes megacolon, constipation and obstruction

``` anal canal differences above and below pectinate line origin? innervation? arterial supply? venous? lymph? ```

above: hindgut endoderm, autonomic visceral nerves, inf mesenteric artery, portal vein, internal iliac lymph nodes below: proctodeum ectoderm, pudendal nerve/somatics (sensitive to stimuli), internal pudendal artery, caval venous system, superficial inguinal lymph nodes

liver pancreas and gallbladder are belong to?

foregut

midgut remains connected to ____ by the _____

yolk sac | vitelline duct

septum transversum

becomes the diaphragm so we have division of thorax upper and abd cavity lower

liver growth

FAST compared to the lung which isnt used as fetus | liver is the largest organ during development

pancreas development

ventral and dorsal combine into one | two ducts form the ampulla vader (main pancreatic duct + common bile duct)

common bile duct is formed by

common hepatic duct and cystic duct

circulation through liver lobule

portal vein drains GI tract low oxy blood flows from portal vein through zone 1 -->2 -->3 --> then drains out center vein ***Zone 3 = area of necrosis = area of lowest oxygen -only 2 cells in thickness so absorption can occur!

obliterated bile duct causes

distended hepatic duct; bile cant get to duodenum

agenesis of gallbladder

usually not a problem because bile can drain directly into duodenum

pulmonary hypoplasia

incomplete development of lung causing diminished size or lack of acini associated with diaphragmatic hernia (less room for development) or renal dysplasia (pushes up diaphragm--> pressure on lungs)

neonatal cholestasis

bile cannot flow into duodenum

biliary atresia

lack of lumen in extrahepatic biliary tract; causes cholestasis in kids hepatic and bile duct obstruction

ARPKLD

AR polycystic kidney and liver disease most severe is perinatal type (stillborn or death by 6wks with huge symmetrical renal masses) neonatal and juvenile type --> liver fibrosis and cystic changes in liver and kidneys

ventral pancreatic bud becomes

uncinate process, pancreatic head and main pancreatic duct