GI Devo Flashcards
What is the ‘challenge of the embryo’ from a GI standpoint
form a continuous mucos membrane lined musclar tube running length of the body
What are the 3 precursors of the GI system?
Endoderm
Splanchinic Mesoderm
Coelomic epithelium covering the splanchnic mesoderm
During folding of the embryo, folding the ______ plane creates the primitive gut tube
Transverse plane
Folding the in transverse plane creates the primitive gut tube from the:
Endoderm
Folding in the _______ plane creates three subdivisions of the primitive gut: foregut, midgut, hindgut
sagittal
Each subdivision of the primitive gut is associated with a :
ventral branch of the dorsal aorta
The foregut receives it’s blood supply from:
celiac trunk
The midgut recieves it’s blood supply from:
Superior mesenteric artery
The hindgut recieves it’s blood supply from:
the inferior mesenteric artery
What makes up the foregut?
Esophagus, stomach, duodenum (first and second parts)
Liver, GB, Spleen
What makes up the midgut?
duodenum (3rd and 4th parts), jejunum, ileum, cecum, appendix, ascending colon, transverse colon (proximal 2/3)
What makes up the hindgut?
Transverse colon (distal 1/3), descending colon, sigmoid colon, retcum to ano-rectal line
Failure or incomplete re-canalization of the duodenum causing COMPLETE OCCLUSION
Dudoenal atresia
Failure or incomplete re-canalization of the duodenum resulting in PARTIAL OCCLUSION
Duodenal stenosis
occurs with duodenal ATRESIA bc the complete blockage prevents intestinal absorption of swallowed amniotic fluid
Polyhydramnios (excess amniotic fluid in the amniotic sac)
Gastroschisis results from a defect in the:
anterior abdominal wall
What happens in gastroschisis
abdmominal viscera extrude through wall w/out involvement of the umbilical cord.
Why is gastroschisis bad news for the viscera of the intestines?
Because viscera gets exposed to amniotic fluid: causes serosistis or inflammation
Where does gastroschisis usually occur?
on the right side lateral to the umbilicus
What is the etiology of gastroschisis?
not well understood: multifactoral, vascular event and enviromental factors
NOT A HERNIA!!!!
Herniation of the abdominal viscera into teh proximal umbilicus
omphalocele
What happens in an omphalocele
intestines fail to return to the abdomen
can include the liver, stomach and gonads
IG associated with other congenital abnormalities; cardiac and urogenital defects
occurs when guts fail to rotate completely upon returning to the body cavity
nonrotaiton or malrotation
What happens to the positioning of the small and large intestine in nonrotation?
large intestine located more leftward
small intestine located more rightward
Reverse rotation (clockwise vs counterclockwise) results in ____ positioing of the duodenum in relation to the transverse colon
anterior
Mispositioned intestine can lead to:
volvulus: obstruction, infarction, tissue death
outpocketing of the ileum resulting from persistence of teh vitelline duct
Meckels diverticulum
What can happen with Meckels diverticulum?
cysts and fistula can occur also and become inflammed; mimicking appendicitis
Meckels diverticulum contains all layers of the ____ and can include epithelial cell types of the stomach and pancreas; enzymes
Ileum
Aganglionosis of the colon that presents as a megacolon
Hirschsprungs disease
Whats going on in Hirschburgs disease?
enlarged dilated region contains normal neural crest derived ganglion cells; dilation occurs d/t affected tissue that lacks ganglion cells, fails to relax; prevents movement of normal bowel contents
