Embryo of the GI Tract

Question 1

Time frame for development of the GI tract

Answer 1

4th to 10th weeks

Question 2

Txn factor for the esophagus

For the duodenum and pancreas

For the SI

For the LI

Answer 2

SOX2

PDX1

CDXC

CDXA

Question 3

The development of the GI tract requires the communication between what two embryonic layers?

Answer 3

Endoderm (epithelium) and splanchnic mesoderm (mesenchyme)

Question 4

How might epithelium cause an atresia in the gut tube?

Answer 4

Temporarily occludes it, but then never re-canalizes

Question 5

Where is the oblique muscle layer when it is included in the GI wall?

Answer 5

Innermost, just after the submucosa

Question 6

The mesentery is made from what layer?

Answer 6

Parietal peritoneum (splanchnic mesoderm)

Question 7

Where is the only place where ventral mesentery can be seen in an adult?

Answer 7

Falciform ligament and lesser omentum

Question 8

Innervation of the foregut

Spinal roots

Answer 8

Greater splanchnic n. and celiac plexus

T5-9

Question 9

Innervation of the midgut

Spinal nerve roots

Answer 9

Lesser splanchnic n. and superior mesenteric plexus

T9-12

Question 10

Innervation of the hindgut

Spinal nerve roots

Answer 10

Least splanchnic n. and inferior mesenteric plexus

T12-L2

Question 11

In the pathway of sympathetic innervation, the “prevertebral ganglia” that the splanchnic nn. go to after leaving the abdominal sympathetic trunk are where?

Answer 11

Celiac, SM, and IM plexuses

Question 12

Parasympathetic innervation of foregut

Midgut?

Answer 12

Vagus n.

SAME

Question 13

Parasympathetic innervation of hindgut (w/ levels)

Answer 13

Pelvic splanchnic nn. (S2-4)

Question 14

If urine is leaking from an umbilicus, what is the problem?

Answer 14

Patent allantois (to become the urachus)

Question 15

If feces is leaking from an umbilicus, what is the problem?

Answer 15

Patent vitelline duct (to be Meckel’s diverticulum)

Question 16

3 Tx’s for a double tracheoesophageal fistula

What is crucial to these?

Answer 16

Colon interposition
Gastric tube esophagoplasty
Gastric transposition

MUST KEEP BLOOD SUPPLY IN TACT

Question 17

Esophageal diverticulum

Answer 17

Blind benign pouch off the side of the esophagus that could collect food/liquid

Question 18

Why does the stomach turn?

Answer 18

Posterior grows faster than anterior, so needs more space to keep growing

Question 19

If, 2-3 weeks after birth, a baby is vomiting NON-GREEN stuff after feeding, what is most likely the problem?

What can sometimes be seen externally?

Answer 19

Hypertrophic pyloric stenosis

Bloated stomach and/or duodenum poking through ant. abd. wall

Question 20

Double bubble sign

Answer 20

2 bloated areas on x-ray (stomach and duodenum) due to a duodenal atresia (occlusion)

Question 21

What organs develop in the ventral mesentery?

Answer 21

Liver and gall bladder

Stomach and part of duodenum

Question 22

Why are there often 2 duodenal papillas?

Answer 22

B/c ventral and dorsal “buds” of pancreas were both connected until they fused

Question 23

What 2 areas signal the liver to develop in the right place?

Where does it end up coming from?

Answer 23

Heart and septum transversum

Posterior endoderm

Question 24

Why does the lesser sac become so small?

Answer 24

The liver grows into the right “sac” and fills it in

Question 25

If someone presents w/ jaundice, dark urine, and pale stool, what is a likely Dx?

Answer 25

Extrahepatic biliary atresia (incomplete formation of bile duct)

Question 26

Normal level of referred pain for the GB

Answer 26

L1

Question 27

Txn factor for inducing islets of langerhaans, D-cells, and pancreatic acinar cells to form

Answer 27

Pax 4

Question 28

Txn factor for making glucagon-producing cells

Answer 28

Pax 6

Question 29

Cause of annular pancreas

Answer 29

Does not rotate w/ stomach

Question 30

Most common places for accessory pancreatic tissue

Answer 30

Near stomach or ileum

Question 31

Most common cause of gut atresias or stenoses in the duodenum

In the SI and LI?

Answer 31

Failure to re-canalize

Vascular compromise

Question 32

Apple peel atresia

Answer 32

Vascular issue leads to short jejunum and small coiled ileum and LI around the SMA or its branches

Question 33

At about what time is the midgut expected to “herniate” into the umbilical cord?

Why?

About when does it come back into the body?

Answer 33

6 weeks

Growing faster than the body has space for

10 weeks

Question 34

Common problem w/ twisting of midgut after it comes out of the umbilical cord

Answer 34

Volvulus

Question 35

When one part of the GI tract is shoved within that of another, what is that called?

Often affects what?

Answer 35

Intussuseption

Blood supply

Question 36

Omphalocele

Answer 36

Unresolved umbilical herniation

Question 37

Gastroschisis

Maybe linked to what behavior by mom?

Answer 37

Body wall doesn’t fuse, abdomen is protruding through a “hole” in the body wall w/o being in the cord

Cocaine use

Question 38

Prune Belly / Eagle-Barrett syndrome

Involved w/ what layer?

Often what other abnormality?

Answer 38

Lack of abdominal wall muscles, abdomen is very large and unrestrained in size

Mesoderm

Cryptorchidism

Question 39

Ileal fistula

Answer 39

Fecal matter discharges through patent vitelline duct

Question 40

Hirschprung’s Disease

Answer 40

Megacolon

Lack of migration of neural crest cells to the hindgut, so no enteric NS for peristalsis

Question 41

Name when anus does not reach the external environment

Answer 41

Imperforate anus

Question 42

High anorectal malformation

Low

Answer 42

No musculature for defecation (anorectal agenesis)

Blind sac below pelvic diaphragm (anal agenesis)