Flashcards in Digestive System Deck (34):
List the structures of the GI tract in order starting with the stomach
Stomach, Duodenum, Jejunum, Ileum, Cecum, Ascending colon, Transverse colon, Descending colon, Sigmoid colon, Rectum, Anus
What are the three developmental sections of the GI tract?
Foregut, Midgut, Hindgut
Name the vessel off the aorta for each embryonic GI section
Foregut - Celiac trunk, Midgut - Superior mesenteric artery, Hindgut - Inferior mesenteric artery
What is the farthest structure into the GI tract which is innervated by the vagus nerve?
The distal portion of the transverse colon
From what embryonic GI structure is the duodenum derived?
Foregut and midgut
What is the arterial supply of the duodenum?
Celiac and superior mesenteric arteries
Does the duodenum occupy an intraperitoneal or retroperitoneal position?
Both. The 1st portion is intraperitoneal, the 2nd through 4th portions are retroperitoneal
Where are the dorsal and ventral pancreatic ducts when they fuse?
At the foregut-midgut junction
When the dorsal pancreatic duct persists what is it called?
The accessory pancreatic duct
What is an annular pancreas, what causes it, and what might it cause?
When the dorsal and ventral pancreas buds dont properly fuse. It can happen when the two buds migrate opposite directions, and it can cause duodenal stensosis (ventral pancreas sits right on duodenum)
What happens to the duodenal lumen during development?
It is obliterated in the 5th or 6th week and recanalized by the end of the 8th week
What is the difference between duodenal stenosis and duodenal atresia
Stenosis is a partial occlusion, atresia is a complete occlusion
Where are duodenal stenosis and duodenal atresia respectively most common?
Stenosis - 3rd and 4th portions of duodenum, Atresia - 2nd or 3rd portion of duodenum
Why is polyhydramnios present with duodenal atresia?
Because the embryo normally swallows amniotic fluid, but cannot if the duodenum is completely occluded
What do we typically look for when checking for possible duodenal atresia?
A double bubble appearence on ultrasound. Air will be present in both stomach and duodenum.
Invasion of the caudal portion of the septum transversum by the liver bud creates what structure?
The ventral mesentery
What are the derivatives of the ventral mesentery?
Falciform ligament, lesser omentum (divided into hepatogastric ligament to left and hepatoduodenal ligament to right)
What are the derivatives of the midgut?
Duodenum (some of 2nd portion, all of 3rd and 4th portion), Jejunum, Ileum, Cecum, Appendix, Ascending Colon, Two thirds of Transverse colon
When does umbilical herniation start and when does it return?
6th week to 10th week
An abdominal wall defect in which the intestines, liver, and occasionally other organs remain outside abdomen
Congenital abdominal wall defect in which the intestines and sometimes other organs develop outside the fetal abdomen through an opening in the abdominal wall
A 90 degree CCW rotation while in cord around axis of SMA, and a 180 degree CCW rotation during reduction of hernia
Are each of the following fused or mobile, ascending colon, descending colon, transverse colon
Ascending and Descending are fused (to pos abdominal wall), Transverse has some mobility (fuses with pos wall of greater omentum)
A twisted intestine, may compromise blood supply
Left sided colon
When the gut rotates 90 degrees cw instead of ccw during development
What most likely causes gut atresias and stenoses
Meckels (Ileal) Diverticulum
Failure of vitelline duct to degenerate completely (can cause ulceration, bleeding, perforation)
What separates the allantois and hindgut?
What are the two divisions of the cloacal chamber?
Rectum and urogenital sinus
What are four conditions that may arise from abnormal hindgut development?
Persistent cloaca, anal stenosis, fistulas of various types, rectal atresia
Two types of hindgut fistulas
Urorectal fistula (connects distal hindgut to urinary system) and Rectovaginal fistula (connects rectum to vagina)
What might be one cause of rectal stenosis
Failure of neural crest cells to migrate and bring innervation to distal hindgut (no innervation will cause stenosis). This situation can cause congenital megacolon (Hirschsprung disease)
What is the primary concern regarding malrotation of the gut during physiologic herniation?
A malrotation may lead to a kinked superior mesentary artery