GI Flashcards
The digestive tube is derived from what embryonic structure?
the yolk sac (later endoderm)
the lining of the GI tract and visceral organs is derived from which primary germ layer?
endoderm; GI epithelium, glands; many organs bud off: liver, pancreas and trachea
The stroma (CT) and muscles of the GI tract are derived from which primary germ layer?
mesoderm; stroma, muscles, peritoneum and spleen
The IMA is derived from which embryonic structure?
hindgut; transverse colon to rectum
The transverse colon to the rectum is supplied by which artery and is derived from what embryonic structure?
the IMA and the hindgut
The SMA is derived from which embryonic structure?
midgut; ampulla of vater to the transverse colon
the ampulla of vater to the transverse colon is supplied by which artery and is derived from what embryonic structure?
the SMA and the midgut
The celiac trunk is derived from which embryonic structure?
the foregut; mouth (oral cavity) to the ampulla of vater
The mouth (oral cavity) to the ampulla of vater is supplied by which artery and is derived from what embryonic structure?
the foregut and the celiac trunk
Mesentery is derived from which germ layer?
mesoderm
Dorsal mesentery
greater omentum; gut moves away from posterior wall in development and covers most abdominal structures
Structures that the ventral mesentery cover?
the lesser omentum and falciform ligament; bottom of the esophagus, stomach and upper duodenum; liver grows into it; derived from the septum transversum
ventral mesentery are what structures in an adult?
lesser omentum and falciform ligament; derived from the septum transversum
What structure divided the foregut structures (respiratory diverticulum which forms the lung buds and the esophagus)?
tracheoesophageal septum; abnormal septum development leads to esophageal atresia (closed esophagus) when the septum deviates posteriorly
Characteristic findings in a neonate with esophageal atresia
esophagus does not connect to stomach, fetus will not be about to swallow fluids leading to polyhydramnios; when born baby will present with drooling, choking and vomiting (unable to swallow secretions building up in oral cavity); diagnosis with NG tube unable to go into stomach because of closed cavity
Physiology herniation of the midgut
6th week of development, abdomen becomes too small so intestines herniate through umbilical cord; visible on fetal ultrasound; reduction of herniation by 12th week
Omphalocele vs Gastroschisis
both are pediatric abdominal wall defects
- omphalocele - abnormal rotation of the midgut; contents will be covered by peritoneum (membrane) and will be midline
- gastroschisis - full thickness abdominal wall defect; contents will NOT be covered by membrane, elevated maternal AFP because it leaks out, and will be paraumbilical (typically to the R) - note that insertion site is usually normal and separate from the defect
omphalocele
pediatric abdominal wall defects; abnormal rotation of the midgut; contents will be covered by peritoneum (membrane) and will be midline
associated congenital abnormalities to omphalocele
trisomy 21 (few associated abnormalities with gastroschisis)
gastroschisis
full thickness abdominal wall defect; contents will NOT be covered by membrane, elevated maternal AFP because it leaks out, and will be paraumbilical (typically to the R) - note that insertion site is usually normal and separate from the defect; pt will later have poor GI function after repair
the midgut rotates around what structure in development?
the SMA
Where should the cecum be located after midgut rotation has taken place?
cecum should be in right lower quadrant where it is normally located
malrotation of the midgut can lead to what defect?
volvulus - small bowel twist around SMA, there is vascular compromise leading to ischemia; presents with vomiting, sepsis, distended abdomen and blood in stool; tx w urgent surgery
L sided colon (cecum) can develop from which malformation?
malrotation of the midgut during development