Development of Digestive System Flashcards
Gastrulation occurs in week _____ and is the process in which we form what 3 germ layers?
3
Ectoderm, mesoderm, and endoderm
T/F: All 3 germ layers contribute to formation of the GI tract
True
How does endoderm contribute to the GI tract?
It gives rise to the epithelial lining & glands of the GI tract
The foregut forms from the head or tail fold?
head
The hindgut forms from the head or tail fold?
tail
What structure is a temporary connection between the midgut and yolk sac?
Vitelline duct
During ______ folding, yolk sac endoderm is incorporated as embryonic midgut
lateral
The primitive gut tube extends cranially all the way to the _______ membrane
oropharyngeal
The primitive gut tube extends caudally all the way to the ______ membrane
cloacal
The oropharyngeal membrane ruptures in what week?
week 4
The cloacal membrane is formed by the pinching together of what two -derm layers?
ectoderm
endoderm
The cloacal membrane ruptures in what week?
week 8
Mesoderm and endoderm both contribute to parts of the ____ of the GI tract
walls
Splanchnic mesoderm forms what in relation to the GI tract?
smooth m. & CT of GI tract
T/F: All inner epithelial lining of anything coming from the digestive tract is derived from mesoderm.
False. It is all derived from endoderm
Peritoneum & Mesenteries are derived from what germ layer?
Mesoderm
Parietal peritoneum is derived from what type of mesoderm?
somatic
Visceral peritoneum, dorsal mesentery, and ventral mesentery are derived from what mesoderm?
splanchnic
Thin serous membrane lining the organs is termed what?
visceral peritoneum
A double-layer of peritoneum that suspends an organ from the body wall is termed what?
Mesentery
The _____ mesentery exists throughout the whole abdominal cavity, while the ______ mesentery disappears in the lower abdomen
dorsal
ventral
T/F: Mesentery can serve as a route of travel (conduit) for blood vessels, lymphatics, and nerves to travel from the body wall to the organs and from organ to organ.
True
______ body folding creates Mesenteries by stretching out splanchnic mesoderm
Lateral
The ventral mesentery is resorbed inferior to the ________
foregut
Mesogastrium is the mesentery of the ______
stomach
The ______ mesogastrium is split into two pieces by the liver
ventral
The ventral mesogastrium is split by the outgrowth of what structure?
liver
In gross anatomy, the ventral mesogastrium between the liver and ant. body wall is described as what?
falciform ligament
Any mesentery at the level of the stomach is called what?
mesogastrium
In gross anatomy, the ventral mesogastrium between the liver and the stomach is termed ____ ___. This structure has two ligaments associated with it, what are they?
Lesser omentum
hepatogastric & hepatoduodenal ligaments
In gross anatomy, the dorsal mesogastrium is termed what?
Greater omentum
The dorsal mesogastrium of the duodenum is called what?
Mesoduodenum
The dorsal mesogastrium of the small intestines is called what?
Mesentery proper
The dorsal mesogastrium of the large intestine (aka the colon) is termed what?
Mesocolon
The ectoderm contribution to the GI tract is in the form of what?
Neural Crest Cells
From weeks 5 to 7 neural crest cells will migrate away from neural tube and enter the wall of the digestive tract and will form the _____ _____ system
enteric nervous
T/F: The enteric nervous system functions autonomously
True
The foregut extends from the _____ down the stomach until halfway across the _____
esophagus
duodenum
The midgut extends from halfway across the _____ to 2/3 across the _____ ____
duodenum
Transverse colon
The hindgut extends from 1/3 of the _____ _____ to the _____
Transverse colon
anus
Foregut is supplied by what artery?
Celiac trunk
Midgut is supplied by what artery?
Superior Mesenteric a
Hindgut is supplied by what artery?
Inferior Mesenteric a
All branches of the ‘-gut’ arterial supply are derived from what artery?
abdominal aorta
From superior to inferior what are the main branches of the abdominal aorta?
Celiac Trunk a
Superior Mesenteric a
Inferior Mesenteric a
What is the main artery that supplies the pharynx?
Pharyngeal arch aa.
What six structures are derived from the Foregut?
Pharynx Lower Respiratory system Esophagus Stomach Proximal 1/2 of duodenum Associated organs (liver, gall bladder, biliary system, pancreas)
In the 4th week, we see a outgrowth of endoderm from the esophagus ventrally that is called what?
Respiratory diverticulum (Tracheo-bronchial diverticulum or lung bud)
The respiratory diverticulum will form what structures in the adult human?
Trachea
Respiratory tree
lungs
What week does the stomach develop?
Week 4
The _____ side of the stomach expands faster and forms the ____ _____
dorsal
greater curvature
The ____ side of the stomach expands slower and forms the ____ ____
ventral
lesser curvature
T/F: While looking from the superior view during embryologic development the stomach undergoes 90 degree counterclockwise rotation
False: Stomach undergoes 90 degree clockwise rotation
The greater curvature of the stomach is on the _____ side of the body, the lesser curvature of the stomach is on the _____ of the body
left
right
The right vagus n. supplies ____ stomach
dorsal
The left vagus n. supplies the ____ stomach
ventral
The ventral stomach is supplied by the ___ ____ nerve
left vagus
The dorsal stomach is supplied by the ____ ___ nerve
right vagus
What day does rotation of the stomach occur?
Day 35
Why does the stomach shift to the left?
Because the dorsal side expands faster and causes the shift
What structure forms between 2 leaves of dorsal mesogastrium in week 5?
Spleen
As the stomach rotates the dorsal mesogastrium is carried to the ____, while the ventral mesogastrium is carried to the ____
left
right
This structure is an enlargement of the peritoneum to a sizable recess between the stomach and post. abdominal wall
omental bursa (lesser sac)
What causes the omental bursa?
stomach rotation to the left
T/F: Greater Omentum can shift and seal off wounds in the abdominal cavity to prevent infections from spreading
True
This structure forms a C-shaped loop distal to stomach
Duodenum
The Foregut- Midgut split occurs where?
Just distal to opening for pancreatic & common bile ducts (major duodenal papilla)
The duodenum twists in a ____ direction, along with the stomach
clockwise (to the right)
T/F: The proximal duodenum and pancreas become pressed against the posterior wall
False: The distal duodenum and pancreas become pressed against the post. wall
The duodenum and Pancreas are ______ retroperitoneal
secondarily
The kidneys are ______ retroperitoneal
primarily
Structures located retroperitoneal are sandwiched between _____ and ____
dorsal body wall
parietal peritoneum
What structure emerges ventrally from endoderm of distal foregut during the 4th week of embryological development
Hepatic diverticulum
The Hepatic Diverticulum gives rise to what?
Liver, gall bladder, and bile ducts
The Liver, gall bladder, and bile ducts are derived from what embryological structure?
Hepatic diverticulum
The embryological origin of the diaphragm is termed what?
Septum Transversum
What develops from the distal foregut as two endodermal buds?
Pancreas
As the duodenum rotates the ____ bud of the pancreas swings with it in a CW direction
ventral
The ventral bud of the pancreas becomes the _____ process and the ____ portion of the _____ of the pancreas
uncinate
inferior
head
The main pancreatic duct is a fusion of the _____ portion of the dorsal bud duct + ventral bud duct
distal
The distal portion of the dorsal bud duct and ventral bud duct fuse to form what?
Main pancreatic duct
The Accessory pancreatic duct is derived from what structure?
proximal dorsal bud duct
What is the resulting term, if the two portions of the ventral bud of the pancreas don’t fuse together prior to rotation, resulting in an obstructive ring around the duodenum
Annular Pancreas
What two clinical symptoms would Annular Pancreas result in?
bile stained vomit and whitish gray feces
What 7 structures are derived from the Midgut?
Distal 1/2 of duodenum Jejunum Ileum Cecum Appendix Ascending colon Proximal 2/3 transverse colon
As intestines of midgut grow they form a ‘U-shaped’ loop that extends _______
ventrally
Where the cranial (superior) limb of the ‘U-shaped’ midgut loop meets the caudal (inferior) limb of the loop meet is where we have what structure?
Vitelline (omphaloenteric) duct
The cranial limb gives rise to all of what structure?
small intestine (distal duodenum, jejunum, and proximal ileum)
The caudal limb gives rise to what structures?
Distal ileum
Cecum+appendix
Ascending colon
Proximal 2/3 transverse colon
The vitelline duct comes out right at the _____ level
ileum
When does the physiological umbilical herniation occur?
Weeks 6-10
Insufficient room in the abdominal cavity leads to temporary herniation of midgut loop into the proximal umbilical cord this is termed what?
Physiological umbilical hernia
A persisting umbilical hernia is called what?
Congenital Omphaloceoele
A hernia of small intestine and occasionally other abdominal viscera through anterior body wall is termed what?
Gastrochisis
T/F: In Gastrochisis the hernia is always lateral to the umbilical cord
True
T/F: A long exposure to amniotic fluid will not harm viscera
False
The first midgut rotation occurs in what week?
Week 6
The week 6 rotation when viewed anteriorly goes in what direction?
90 degrees in a counterclockwise direction
During the first midgut rotation the axis of rotation is what structure?
Superior mesenteric artery
After the first midgut rotation all of the small intestines will be located on the persons ____ and all the large intestines will be located on the persons _____
right
left
Prior to the first midgut rotation the large intestine is located _____ to the small intestine
inferior
At week ____ the intestines can come back in the abdomen
10
The second midgut rotation rotates _____ degrees in a _____ direction
180
counterclockwise
In total the midgut loop undergoes _____ degrees of rotation in 2 parts
270
As cecum is being dragged down our ascending colon ends up on the _____ and our descending colon ends up on the ____
right
left
As the cecum is being dragged down the ascending colon and descending colon are being pushed to the posterior wall causing these structures to become ______
secondarily retroperitoneal
What 5 structures are retroperitoneal?
Distal duodenum Pancreas Ascending colon Descending colon Kidneys
Which structure(s) are secondarily retroperitoneal?
Distal duodenum
Pancreas
Ascending colon
Descending colon
Which structure(s) are primarily retroperitoneal?
Kidneys
What 6 structures are intraperitoneal?
Stomach Proximal duodenum Jejunum Ileum Transverse colon Sigmoid colon
In cases of non rotation you end up with all of large intestine on the ___ side and all of small intestine are on the ____ side
left
right
In cases of reverse rotation of the midgut, the ___ rotation is normal, but the ___ rotation is reversed
1st
2nd
In ______ rotation you end up with the midgut and hindgut in normal positions except the _____ is ventral to the transverse cecum instead of behind it
reversed
duodenum
An abnormal rotation that may cause intestinal loop twist around mesenteric attachment site is termed what?
Volvulus
A volvulus can result in what?
bowel obstruction, compromised blood flow
The abnormal narrowing of a lumen/ orifice is termed what?
stenosis
The condition in which a body lumen or orifice is abnormally closed or absent is what?
Atresia
An abnormal passageway between two organs/ vessels or between an organ and the external environment is what?
Fistula
At week ___ the intestines become occluded by epithelial cells
6
The midgut loop should reanalyze by the end of week ___
8
The most common GI malformation is what?
Meckel’s (ileal) diverticulum
A remnant of what structure causes the Meckel’s (ileal) diverticulum?
vitelline duct
If the vitelline duct fails to degenerate completely it can form what three things?
Vitelline ligament (closes off but stays connected) Vitelline cyst (closes off but fluid is present) Vitelline fistula ( vitelline duct never closed off)
What 5 structures are derived from the hindgut?
Distal 1/3 transverse colon Descending colon Sigmoid colon Rectum Superior portion of anal canal
In week 4 we form a rigid mesoderm termed what?
Urorectal septum
A urorectal septum grows _____ toward the cloacal membrane, dividing it into ______ and ____ membranes
inferiorly
urogenital
anal
the cloaca is partitioned into the ______ _____ (ventrally) and the ______ _____ (dorsally)
urogenital sinus
anorectal canal
This disease affects variable portions of the bowel where the neural crest cells fail to migrate to form the enteric nervous system
Hirschsprung’s Disease
Hirschsprung’s disease normally affects what portions of the bowel?
distal portions usually sigmoid colon and/ or rectum
In Hirschsprung’s Disease, aganglionic portion constricts, bowel distends proximal to constriction and results in what symptoms?
severe constipation
failure to thrive
