Development of the GI tract Flashcards
When is folic acid needed?
→ In the first trimester
What is folic acid used for?
→helps with the fusion and the closure of the spinal cord.
What is spina bifida?
→when the spinal cord herniates out of the back.
When are the primary germ layers formed?
→ During the process of gastrulation
What happens at the beginning of the third week?
→embryo has implanted into the uterine wall
What is the structure of the embryo at 3 weeks?
→The embryo is a flat disc comprised of two cell layers
→Epiblast
→Hypoblast
What do the epiblast cells in the midline of the embryo start to do?
→ Begin to ingress starting from the caudal end
→Visible as the primitive streak
What do ingressing cells differentiate into and what do they surround?
→differentiate into Mesoderm
→Surrounding muscles, connective tissue, mesentery and blood vessels
What does the epiblast give rise to?
→Ectoderm
What does gastrulation give rise to?
→three primary germ layers
→ Ectoderm
→ mesoderm
→endoderm
How is the gut tube formed?
→by folding of sheets of cells in two directions
What are the two ways in which the gut tube folds?
→Folding towards the midline along the cranial-caudal axis
→Folding towards the yolk sac at the cranial and caudal ends
What does the buccopharyngeal membrane form?
→ mouth and throat
What does the cloacal membrane form?
→ urogenital tract
What is the septum tranversum?
→ area where the diaphragm is
What does the somatic mesoderm form?
→ The muscles
What does the Splanchnic mesoderm form?
→ autonomic nervous system
What is the mesentery and what does it do?
→ a folded membrane that anchors the GI tract to the posterior abdominal wall.
→It prevents the organs falling due to gravity.
What is the primary gut tube made up of?
→sheet of endoderm, which makes the epithelia and glands
→surrounding mesoderm, which makes muscle and connective tissue (including mesentery)
How is part of the yolk sac cavity enclosed?
→Part of the yolk sac cavity is enclosed within the embryo by pinching-off the yolk sac to form a yolk stalk and balloon-like yolk sac.
What makes up the foregut?
→Pharynx →Oesophagus →Stomach →Cranial half of duodenum →Ampulla of Vater (joining of bile ducts and pancreatic duct)
What makes up the midgut?
→Caudal duodenum →Jejunum →Ileum →Caecum →Appendix →Ascending colon →Proximal ⅔ of transverse colon
What makes up the hindgut?
→Distal ⅓ of transverse colon
→Descending colon
→Rectum
What artery supplies the foregut?
→ Celiac artery
What artery supplies the midgut?
→ Superior mesenteric artery
What artery supplies the hindgut?
→ Inferior mesenteric artery
What is the gut surrounded by?
→plexus of blood vessels joining vitelline (relating to or associated with the yolk of an egg) vessels to aorta
What does the plexus resolve to form?
→Plexus resolves to form the arteries that supply the GI tract from the aorta
How many arterial branches are there to the thoracic oesophagus?
→5
What innervates the foregut?
→ celiac ganglion
What innervates the midgut?
→ superior mesenteric ganglion
What innervates the hindgut?
→ inferior mesenteric ganglion