GI embryology Flashcards
foregut, midgut and hindgut divisions
foregut - pharynx to duodenum
midgut - duodenum to proximal 2/3 colon
hindgut - distal 1/3 colon to anal canal
foregut rotation
90 degrees clockwise
failure of lateral fold closure causes
gastroschisis or amphalocele
duodenal atresia due to…
failure to recanalize (trisomy 21)
jejunal, ileal, or colon atresia due to
vascular accident
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
gastroschisis
extrusion of abd contents through abd folds NOT covered by peritoneum
omphalocele
persistence of herniation into umbilical cord; IS sealed by peritoneum (not incontact with amniotic fluid)
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
isolated EA CXR
CXR shows gassless abdomen
congential pyloric stenosis
hypertrophy of pylorus causes obstruction
palpable olive mass in epigastric region and nonbilious projectile vomiting at 2-6 weeks old
achalasia
failure of LES to relax
oligohydramnios vs poly hydramnios
oligo - too little amniotic fluid, decreased volume
poly - too much; fetus isnt swallowing
in pharyngeal gut, lining is derived from?
cartilage, muscles, and nerves from?
endoderm
pharyngeal arches
in for, mid, and hind guts,
epithelial lining is from?
muscles and CT from?
enteric nervous system from?
endoderm
splanchic mesoderm
neural crest
gut tube is suspended by
dorsal mesentery
midgut is temporarily connected to yolk sac by____
vitelline duct
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
