Development of the Digestive System Flashcards
the connection b/w the gut and yolk sac during embryonic lateral body folding is known as ?
vitelline duct
epithelial lining and the glands of the GI tract are derivatives of what ?
endoderm
smooth musculature and conenctive tissue of the GI tract are derivatives of ?
splanchnic mesoderm
parietal peritoneum is of what derivative ?
somatic mesoderm
visceral peritoneum is of what derivative
splanchnic mesoderm
what is the peritoneum
serous membrane lining the abdominal cavity and organs
what is a mesentery
double layer of peritoneum that suspends organs from the body wall
what is the derivative of dorsal mesentery
splanchnic mesoderm
what is the derivative of ventral mesentery
splanchnic mesoderm
what type of body folding results in mesenteries
lateral folding
which mesentery is split/divided because of the development of the liver
ventral mesogastrium
which mesentery becomes the greater omentum
dorsal megogastrium
what is the ectodermal contribution to the GI tract
neural crest cells migrate and become the enteric nervous system
what are the 3 main divisions of the GI tract, and where are those divisions
foregut - esophagus to mid duodenum
midgut - mid duodenum to proximal 2/3 transverse colon
hindgut - distal 1/3 of transverse colon to asshole
what is the basis of how the different regions of the GI tract are divided ?
based upon blood supply
what artery supplies the foregut
celiac trunk a.
what artery supplies the midgut
superior mesenteric a.
what artery supplies the hindgut
inferior mesenteric a
all arterial supply to the GI tract are branches off what main artery
dorsal aorta
what are some of the foregut derivatives
pharynx, lower resp. system, esophagus, stomach, proximal 1/2 of duodenum
what is the special name of the endodermal lung bud on the ventral side of the foregut
respiratory diverticulum or tracheo-bronchial diverticulum
what side of the foregut becomes to the greater curvature and what side does it face after curvature
dorsal side, will be on left
what type of rotation does the stomach undergo
90 degree clockwise rotation
what is the recess behind the stomach created by the 90 degree rotation that allows the stomach to expand during eating
omental bursa
what are the organs that are secondarily retroperitoneal (behind the abdominal cavity) ? what causes this to happen ?
duodenum and pancreas
-shifting of stomach 90 CW causes them to turn
what endodermal outpouch gives rise to the liver, gall bladder, and bile ducts
hepatic diverticulum
what organ develops from 2 seperate endodermal buds, one dorsal and one ventral then eventually fuse
pancreas
the unicate process is + inferior portion of the head of the pancreas are derivatives from what bud of the pancreas
ventral bud
the main pancreatic duct is made from ?
distal dorsal bud duct + ventral bud duct
the accessory pancreatic duct is made form ?
proximal dorsal bud duct
what is the condition of annular pancreas
rare condition where ventral bud develops and fuses early causing an obstructive ring around the duodenum = vomiting bile
what are some of the midgut derivatives
distal duodenum, jejunum, ileum, cecum, ascending colon, and proximal 2/3 transverse colon
what is a physiological umbilical herniation and when does this ovvur ?
temporary herniation of intestines in midgut loop into the proximal umbilical cord around week 6-10
-NORMAL cuz intestines forming faster than body cavity
what is congenital omphalocoele
persisting umbilical herniation w/in proximal umbilical cord
what is gastrochisis
hernia of small int. that doesnt involve umbilical cord
explain how the midgut loop undergoes 270 degree rotation
1st part - 90 degree CCW while midgut loop still in proximal umbilical cord
2nd part - 180 degree CCW rotation as intestines return to abdomen cavity
what is the axis of rotation during the rotation of the midgut
superior mesenteric a. (SMA)
what parts of the midgut become secondarily retroperitoneal after rotation
ascending colon and descending colon
kidneys are primary or secondarily retroperitoneal
primarily meaning developed w/in peritoneal cavity and remained in the peritoneal cavity
what is the end result in a case of non rotation of the midgut
Normal 1st rotation BUT NO 2nd rotation
- small intestines on right
- Lg. intestines on left or Left sided colon
what is the end result of a reversed rotation of the midgut
Normal 1st rotation BUT reveresed 2nd rotation
-All in normal posistion EXCEPT duodenum is ventral to transverse colon (usually function normally)
what is volvulus and what causes it ?
abnormal rotation of midgut intestinal loop = bowel obstruction leading to multiple disorders
stenosis
abnormal narrowing/constriction
atresia
abnormally closed or absent lumen
fistula
abnormal passageway b/w 2 structures
explain recanalization of the midgut loop
intestines are temporarily plugges at week 6 then
RECANALIZE by epithelial cells dying off eventually reforming lumen at week 8
what is Meckel’s Diverticulum
- most common GI malformaiton (especially males)
- vitelline duct persists as fingerlike outpouching of ileum potentially causing a fistula b/w belly button and intestine =shit out of belly button
what are the hindgut derivatives
distal 1/3 of transverse colon, descending colon, sigmoid colon, rectum, anus
the rectum and anal canal are both derivatives of what
cloaca or cloacal membrane
what divides the cloacal membrane into seperate urogenital membranes and anal membranes
urorectal septum
how is the partitioning of the cloaca into the urogenital sinus and anorectal canals organized on the body
urogenital membrane ventrally
anorectal canal dorsally
what is Hirschsprungs disease
-Aganglionic megacolon
nueral crest cells fail to migrate and form enteric nervous system
-causes constant constriction of bowel cuz no nervous system to relax = blocks colon and severe constipation
