Development of the GIT Flashcards
What is responsible for holding the organs of the GIT in place?
Mesentery
The GIT has intrinsic neurones for motility reflexes. What are intrinsic neurones?
A type of afferent neurone which connects motor neurones to sensory neurones
The GIT has vagal and pelvic nerves. What do the vagal nerves do?
A vagus nerve is responsible for carrying signals between the heart, brain and digestive systems
What is the parietal peritoneum?
The lining of the walls of the abdominal cavity
What is the name of the membrane that surrounds the individual organs?
Visceral peritoneum
Which of the 3 germ layers is the GIT formed from?
Endoderm
How is the gut tube formed?
1) Endoderm folds and elevates
2) Endoderm folds around ventrally
3) Endoderm fuses ventrally
Where does the splanchic mesoderm come from?
The lateral plate mesoderm
What is the name of the membrane at the two openings of the primitive gut?
Buccopharyngeal membrane (mouth end)
Cloacal membrane (anal end)
What does the foregut form?
Foregut forms the oesophagus, the stomach, the gall bladder, the bile ducts, the pancreas and the proximal duodenum
How is the stomach formed during the rotation of the foregut?
1) Foregut rotates 90 degrees along the longitudinal axis
2) Tube bulges out to the left side
3) Further rotation along the ventrodorsal axis
What is the greater omentum formed from?
Dorsal mesentry
What is the lesser omentum formed from?
Ventral mesentry
What do each of these ligaments in the greater omentum link together?
1) Gastrophrenic
2) Gastrocolic
3) Gastrosplenic
4) Phrenicosplenic
1) Stomach to diaphragm
2) Stomach to transverse colon
3) Stomach to spleen
4) Diaphragm to spleen
What do each of these ligaments in the lesser omentum attach?
1) Hepatophrenic
2) Hepatogastric
3) Hepatooesophageal
4) Falciform
1) Liver to diaphragm
2) Liver to stomach
3) Liver to oesophagus
4) Liver to ventral abdominal wall
As the stomach forms, there is also an out pocketing on the ventral side of the gut tube. What does this form?
- Ventral pancreatic bud and duct
- Gall bladder
- Liver buds
The ventral pancreatic bud and duct must then move to sit alongside the dorsal pancreatic bud and duct. How does this happen?
1) There is a clockwise rotation through the proximal duodenum
2) Ventral and dorsal pancreatic ducts fuse
How does the spleen form?
It forms from mesodermal cells in the dorsal mesentry
What is physiological herniation?
The process in which the midgut grows and loops out of the umbilical cord
What happens during physiological herniation?
1) Midgut lengthens out of the umbilical cord, rotates 90 degrees clockwise around the central artery within the cord
2) Intestines retract and undergo 180 degree rotation about the ventro-dorsal axis.
What is the difference in the ascending colon between a pig, a horse, and a ruminants
Pigs = have a spinal loop in a 3D cone shape
Horse = don’t have a spinal loop, instead just a single large loop
Ruminants = Spinal loop in a flat plane
What is the cloaca?
The common end for the hindgut and urogenital tract
How does the hind gut form (to separate the urogenital tract and the hindgut)?
- Urorectal septum grows towards the cloacal membrane
- The perineal body then separates the urogenital and anal membranes
