The Development Of The Gi Tract Flashcards
What does the folding of the embryo in the 4th week create?
Laterally creates the ventral body wall and the primitive gut become tubular, craniocaudally creates cranial and caudal pockets from yolk sac endoderm beginning the primitive gut development
What are the emboryonic divisions of the gut?
Rh foregut the midgut and the hind gut foregut and the hindgut begin ass blind whereas the midgut is continuous with the yolk sac
When does the development of the primitive gut tube begin?
Begins in the third week where it pinches off from the yolk sav cavity
What is the internal lining of the gut tube dervived from?
Endoderm
What is the external lining of the gut tube dervived from?
The spalnic mesoderm, which forms the future musculature and the visceral perioteunum
How is the primitive gut tube suspended in the intraemobryonic colem?
By a double layer of spalhnic mesoderm
What are the adult derviatives of the foregut?
The oesphagus, the stomach, the pancreas the liver and the gall bladder and the duodenum(proximal to the entrance of the bile duct)
What are the adult deriviatives of the midgut?
The dudoenum, the jejunum, the ileum, the cecum, the ascending colon and the proximal 2/3 of the tranverse colon
What are the adult derviatives of the hindgut?
The distal 1/3 of the transverse colon, the descending colon, the sigmoid colon, the rectum, the upper anal canal and the internal lining of the bladder and the urethra
Where does foregut derivied organs get their blood supply from?
The celiac trunk
Where do midgut derivied organs get their blood supply from?
The SMA
Where do hindgut derivived organs get their blood supply from?
The IMA
What are the structures in the gut that may end up with a mixed blood supply?
The dudoenum, proximal to the entry of the bile, the gastroduogenal and the superior pancreaticodudoenal ateries and distal to the entry of the bile duct is the inferior pancretaiotideal, the head of the pancreas is supplied by the coliec tranc, and the SMA
What are the two parts of the mesoderm involved in development of the gut?
The somatic and the splanchic mesoderm
What is a mesentary?
A double layer of periotenum suspending the gut tube from the abdominal wall
How are mesentaries fromed?
The new primitive gut tube is suspended with the intraemobryonic ceoluem, the splanchnic mesoderm surround the new gut and the mesentery is formed from a condensation of this mesoderm
Where do you find the different mesentaries?
He dorsoal medsentary suspends the entire gut tube of the dorsal body wall whereas the ventral mesentery is only found in the foregut region
How do you form the greater and lesser peritoneal sacs?
The dorsal and ventral mesentays in the region of the foregut divide the cavity into left and right sacs in this region only, the left sace contributes to the greater sac whereas the right sac becomes the lesser sac that comes to lie behind the stomach
How is the greater omentum formed?
Formed from the dorsal mesentary and is the frist structure seen when the abdomen is opened anteriorly
How is the lesser omentum formed?
It is formed from the ventral mesentary and the free edge conducts the portal triad
What is the one proccess that leads to the formation of the greater and lesser sacs and the omenta?
Rotation
How does the rotation of the stomach occur?
The primitive stomach rotates in two directions, around the longitudinal axis and around the anteroposterior axis, adn the result is that the greater and lesser curvature come to lie first of the left and right side and the cardia and the plyrous move horizontally and pull the curvature inferiorly
What does rotation of the stomach result in?
Pulls the vagus nerves anterior and posterior to the stomahc instead of left and right, shifts the cardia and the pylorus from the midline so that the stomach lies obliquely, contributes towards moving the lesser sac behind the stomach and creates the greater omenum
What is a peritoneal refelction?
A change in direction from parietal peritoneum to mesentery, from mesentery to visceral peritoneum and from visceral peritoneum……