Digestion Flashcards
The ______ of the primordial gut gives rise to the gut.
endoderm
During body folding (week ___), endoderm from the dorsal portion of ___ ___ is incorporated into the embryo.
4; yolk sac
The yolk sac forms the _____ (innermost/outermost) lining of the primitive gut tube.
innermost
The endoderm of the primordial gut gives rise to the gut, ____ lining, and ___ of the GI tract.
epithelial; glands
what forms during head folding?
foregut
what forms during tail folding
hindgut
The primordial gut is initially closed at its cranial end by the ____ membrane, and at its caudal end by the ____ membrane.
oropharyngeal; cloacal
During ____ (lateral/caudal) folding, the yolk sac ____ (endoderm/ectoderm) is incorporated as embryonic ____(midgut/hindgut).
lateral; endoderm; midgut
The oropharyngeal membrane ruptures at __ weeks and the cloacal membrane ruptures at __ weeks to allow for swallowing of the amniotic fluid.
4; 8
The omphaloenteric, or _____, duct is the connection between the ___ ___ and the ___-gut.
Vitelline; yolk sac; mid-gut
what forms the smooth muscle and connective tissues of the GI tract, including the mesenteries?
splanchnic mesoderm
The _____ (endoderm/ectoderm/mesoderm) forms the peritoneum and mesenteries.
mesoderm
what is a double layer of peritoneum that suspends an organ from the body wall?
Mesentery
which serous membrane lines the abdominal cavity?
parietal peritoneum
which serous membrane lines organs?
visceral peritoneum
T/F. Parietal peritoneum is derived from splanchnic mesoderm.
False. Parietal peritoneum is derived from somatic mesoderm.
Visceral peritoneum is derived from which mesoderm, splanchnic or somatic?
splanchnic
The ventral mesentery is resorbed ____ (superior/inferior) to foregut.
inferior
T/F. The dorsal mesentery is more widespread than the ventral mesentery.
true.
T/F. The ventral mesogastrium forms the falciform ligament and the lesser omentum
True.
What two ligaments can be located in the lesser omentum?
hepatoduodenal and hepatogastric ligaments
what migrates into the walls of the GI tract to form the enteric nervous system during week 5-7)?
neuroectoderm/neural crest cells
Which vessel supplies the foregut? midgut? and hindgut?
celiac trunk; SMA; IMA
what is the arterial supply to the pharynx?
pharyngeal arch aa
what are the foregut derivates?
pharynx, lower respiratory system, esophagus, stomach, proximal 1/2 duodenum, liver, gallbladder, biliary system, and pancreas
During week 4, what is the respiratory diverticulum that appears on the ventral side of the foregut that will become the trachea, respiratory tree and lungs?
tracheo-bronchical diverticulum (lung bud)
T/F. As the stomach enlarges caudal to the esophagus, its ventral side expands faster than the greater curvature.
False.
The DORSAL side = greater curvature
The VENTRAL side = lesser curvature.
In which direction does the stomach rotate?
90o Clockwise (if looking from superior view)
The ventral side (lesser curvature) ends up on which side of the body? How does this affect the vagus nerve distribution?
VENTRAL = right
LEFT vagus supplies the ventral stomach
The dorsal side (greater curvature) ends up on which side of the body? How does this affect the vagus nerve distribution?
DORSAL = left
RIGHT vagus supplies the dorsal stomach
As the stomach rotates, which direction is the dorsal mesogastrium carried?
left
the rotation of the dorsal mesogastrium to the left creates what space?
omental bursa (lesser sac of the peritoneum)
The omental bursal is a recess between what two areas?
stomach and posterior abdominal wall
what structure is carried to the left when the dorsal mesogastrium rotates?
spleen
what structure is formed when the dorsal mesogastrium begins to form a flap over the small intestines?
greater omentum
T/F. The greater omentum is a single layer that hangs over the transverse colon.
False. It is a double layer over the transverse colon.
The ____ (proximal/distal) 1/2 of the duodenum is in the foregut and therefore supplied by the __ __.
proximal; celiac trunk
The ___ (proximal/distal) 1/2 of the duodenum is in the midgut and therefore is supplied by the _ _ _.
distal; SMA
what structure represents the split between the foregut and the midgut?
major duodenal papilla (opening for the pancreatic and common bile ducts)
What direction does the duodenum rotate with the stomach?
clockwise
T/F. The duodenum and pancreas are not retroperitoneal.
False. The distal duodenum and pancreas becomes pressed against the posterior abdominal wall.
What is lost when the duodenum and pancreas move retroperitoneal?
their dorsal mesenteries fuse with parietal peritoneum and are lost.
The duodenum and pancreas are _____ retroperitoneal.
secondarily
The ____ diverticulum emerges ventrally from ____ (endoderm/ectoderm) of distal foregut (week4) and grows superiorly toward the ____ ___ to give rise to the liver, gall bladder and bile ducts.
hepatic; endoderm; septum transversum (future diaphragm)
T/F. The liver, gall bladder, biliary tree and pancreas all develop as endodermal diverticula from the distal foregut.
True.
What are the names of the two endodermal buds that emerge from the pancreas?
dorsal and ventral buds
T/F. As the duodenum rotates, the dorsal bud swings clockwise and fuses with the ventral bud.
False. The VENTRAL bud rotates and fuses with the dorsal bud.
The structures of the pancreas does the ventral bud form?
uncinate process and inferior portion of the head of the pancreas
What is the structure called that forms from the distal portion of the dorsal bud duct and the ventral bud duct?
main pancreatic duct
T/F. The main pancreatic duct forms from the proximal dorsal bud duct.
False. The accessory pancreatic duct forms from the proximal dorsal bud duct.
T/F. The ventral bud of the pancreas develops in two portions.
True.
If the ventral bud portions dont fuse during rotation, each portion may wrap around the duodenum and obstruct it. What condition is this?
Annular pancreas
what are the midgut derivatives?
distal 1/2 duodenum, jejunum, ileum, cecum and appendix, ascending colon, and proximal 2/3 transverse colon
The midgut forms a __-shaped loop.
U
The vitelline duct is where the ____ limb and ___ limb meet.
cranial; caudal
What three structures does the cranial limb of the midgut include?
distal duodenum, jejunum, proximal ileum
what five structures does the caudal limb of the midgut include?
distal ileum, cecum, appendix, ascending colon, and prox 2/3 transverse colon
What leads to temporary herniation of midgut loop into the proximal umbilical cord during weeks 6 - 10 of development? What is this condition called?
insufficient room in the abdominal cavity. Physiological umbilical hernia
If an umbilical hernia persist after birth, what is it called?
congenital omphalocoele
What is noted in a newborn with congenital omphalocoele?
viscera covered by amnion and WITHIN proximal umbilical cord
What condition is often associated with chromosomal abnormalities and results in high mortality?
congenital omphalocoele
T/F. Gastrochisis involves the umbilical cord.
False. It does NOT involve the umbilical cord. It results from herniation thru the anterior body wall.
when does the first midgut rotation occur?
week 6
what is the direction of the 1st midgut rotation? What is the axis of rotation?
90o counter-clockwise.
SMA
when does the 2nd midgut rotation occur?
week 10 as the intestine return to the abdomen
T/F. The cranial limb return first during the 2nd midgut rotation.
True.
what is the direction of the second midgut rotation?
180o counter clockwise
T/F. The ascending and descending colon are secondarily retroperitoneal.
true.
what four structures are secondarily retroperitoneal?
distal duodenum
pancreas
ascending colon
descending colon
define secondarily retroperitoneal
originally developed within the peritoneal cavity, but shifted into retroperitoneal position due to GI growth and rotation.
What structure is primarily retroperitoneal?
kidneys
what structures are intraperitoneal?
(stomach and) prox duodenum
jejunum, ileum
transverse colon
sigmoid colon
If there is no 2nd midgut rotation, the ___ (cranial/caudal) limb returns first and occupies the left side of the abdominal cavity known as left-sided colon.
caudal
what is the result if the 2nd midgut rotation is reversed?
midgut and hindgut are in normal position except duodenum is ventral to the transverse colon (not retroperitoneal)
what condition results from abnormal rotation that caused intestinal loop twisting around mesenteric attachment sites?
vovulus
define stenosis.
the abnormal narrowing of a lumen/orifice (tubular organ or structure)
what condition results when a body lumen or orifice is abnormally closed or absent?
atresia
what is an abnormal passageway between two organs/vessels or between an organ and the external environment?
Fistula
what are the hindgut derivates?
distal 1/3 transverse colon, descending colon, sigmoid colon, rectum and superior portion of the anal canal
what two structures are derived from the posterior portion of the cloaca after it is partitioned by the urorectal septum?
rectum and superior portion of the anal canal
A ____ septum grown inferiorly toward the cloacal membrane, dividing it into ____ and ____ membranes.
urorectal; urogenital; anal
The urorectal septum partitions the cloaca into the ___ ___ (ventrally) and ___ ___ (dorsally).
urogenital sinus; anorectal canal
what causes hindgut fistulas?
if the urorectal septum fails to completely separate the hindgut from the urogenital sinus or if the cloaca is too small
T/F. Hirschsprung’s disease (aganglionic megacolon) results when neural crest cells fail to migrate and form the enteric nervous system.
True.
The aganglionic portion ____ (dilates/constricts) causing the bowel to distend proximal the (dilation/constriction) leading to severe constipation and failure to thrive.
constricts; constriction
