Embryology Flashcards
what gives rise to the epithelial lining and glands of the GI tract?
Endoderm
what type of folding gives us the GI tract?
Cranio-caudal folding
name the 3 gut regions
Foregut
Midgut
Hindgut
what does the ssplanchnic mesoderm become?
Smooth muscle and connective tissue of the GI tract
what forms the peritoneum?
Parietal - somatic mesoderm
Visceral - Splanchnic mesoderm
what forms the mesenteries?
Dorsal and Ventral are BOTH from splanchnic mesoderm
what is the function/structure of mesenteries
double layer of peritoneum that suspends an organ from the body wall
What is the peritoneum?
The serous membrane lining of the abdominal cavity (parietal) and organs (visceral)
what type of folding creates the mesenteries?
Lateral folding
What gives rise to the lesser omentum?
Ventral mesogastrium
what gives rise to the falciform ligament?
ventral mesogastrium
THe ventral mesogastrium gives us what?
Lesser omentum and falciform ligament
the greater omentum is created by what?
dorsal mesogastrium
the mesentery proper gives us what structure?
small intestine
what forms the enteric nervous system of the GI tract?
neural crest cells
what artery supplies the pharynx?
Pharyngeal arch arteries
the foregut is supplied by what?
celiac trunk
THe midgut is supplied by which artery
superior mesenteric artery (SMA)
the hindgut is supplied by what?
inferior mesenteric artery (IMA)
name the foregut derivatives
1) larynx
2) lower respiratory system
3) esophagus
4) stomach
5) proximal half of duodenum
6) associated organs (liver, gall bladder, pancreas)
when does the respiratory diverticulum appear?
week 4
where does the tracheoesophageal septum grow in from?
the lateral sides of the foregut. divide it into lower resp tract and esophagus
what is Stenosis?
abnormal narrowing of a lumen/orafice
define atresia
a body lumen or orifice is abnormally closed or absent
what is a fistula?
abnormal passageway between two organs/vessels
what causes the formation of the greater curvature in the stomach?
the dorsal side of the stomach expands faster, starting at week 4
which vagus nerve supplies the dorsal stomach? the ventral?
Dorsal - right
Ventral - Left
what is the Omental bursa?
The lesser sac of the peritoneum
what causes the enlargement of the Omental bursa?
the rotation of the stomach carries the Dorsal Mesogastrium to the left
where is the Omental Bursa located?
posterior to the stomach, with superior and inferior recesses
what forms the greater omentum?
the dorsal mesogastrium flapping over the small intestines
what artery supplies the duodenum
the celiac trunk - first half
SMA - second half
where does the hepatic diverticulum emerge?
ventrally from endoderm of distal foregut- gives liver, gall bladder and bile duct
the ventral and distal buds of the endodermal foregut form what?
Pancreas
what does the ventral bud of the pancreas become?
uncinate process + inferior portion of head
what makes up the main pancreatic duct?
distal portion of dorsal bud duct
ventral bud duct
the accessory pancreatic duct emerges from what?
proximal dorsal bud duct
what are the midgut derivatives?
distal half of duodenum jejunum ileum cecum & appendix ascending colon proximal 2/3 of transverse colon
the Vitelline duct does what?
connects midgut to yolk sac
what is congenital Omphalocele?
persisting umbilical herniation. Vicera covered by amnion & WITHIN proximal umbilical cord
Gastrochisis
hernia through body wall and does not involve umbilical cord. Exposure to external amniotic fluid can damage viscera
when does the midgut make its first 90 degree rotation?
week 6
what is the 2nd midgut rotation? when does it occur?
180 degree counter-clockwise rotation that brings intestines to their normal position. during week TEN
are the ascending and descending colon within the peritoneum?
NO. they become secondarily retroperitoneal
which structures are intraperitoneal?
A) proximal duodenum
B) Jejunum, Ileum
C) transverse colon
D) sigmoid colon
what structures are retroperitoneal?
A) distal duodenum B) pancreas C) ascending colon D) descending colon E) kidneys
Volvulus
abnormal rotation causes intestinal loop twist around mesenteric attachment. leads to bowel obstruction
recanalization of midgut loop
when Intestines are temp occluded at week 6 because of endodermal growth
what is Meckel’s (ileal) diverticulum?
a remnant of the Vitelline duct. persists as finger-like out pouching of the ileum. may cause ulcers and bleeding
what does the hindgut form?
distal 1/3 of transverse colon decending colon sigmoid colon rectum superior part of anal canal
what does the Urorectal septum do?
divides cloaca into urogenital sinus and the anorectal canal
what is Hirschsprung’s disease? (ananglionic megacolon
ananglionic portion of bowel constricts and decends. Leads to severe constipation
