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GI personal > Development of GI System > Flashcards

Development of GI System Flashcards

1
Q

Cranio-caudal folding pulls in ______ to form the foregut, midgut, and hindgut, beginning at _____ days and complete by ____ days

A

Endoderm; 20; 26

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2
Q

What germ layer forms the mucosal epithelium and GI glands except for the lower 1/3 anus?

A

Endoderm

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3
Q

What germ layer forms the muscular wall, vascular elements, and CT elements of the GI tract?

A

Splanchnic mesoderm

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4
Q

What germ layer forms the enteric ganglia and nerves and glia (neural crest)?

A

Ectoderm

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5
Q

Endoderm forms the mucosal epithelium and GI glands throughout the entire GI tract EXCEPT for the lower 1/3 anus. The epithelium for the lower 1/3 of the anus comes from the _____ germ layer

A

Ectoderm

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6
Q

the _____ _____ forms at week 4 and connects the gut tube to the dorsal body wall; it runs along the entire GI tract

A

Dorsal mesentery

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7
Q

What are the adult derivatives of the embryonic dorsal mesentery?

A

Greater omentum - gastrosplenic, gastrocolic, and splenorenal ligaments

Small intestine mesentery

Mesoappendix

Transverse mesocolon

Sigmoid mesocolon

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8
Q

The ventral mesentery is found between the ventral body wall and foregut, running from ________ to ________

A

Septum transversum; umbilical vein

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9
Q

What are the adult derivatives of the embryonic ventral mesentery?

A

Lesser omentum - hepatoduodenal and hepatogastric ligaments

Falciform ligament of liver

Coronary ligament of liver

Triangular ligament of liver

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10
Q

Why are organs like the ascending/descending colon, duodenum, and bulk of pancreas considered SECONDARILY retroperitoneal?

A

They were initially suspended within mesentery that later fused with the body wall

[primarily retroperitoneal structures were never included in peritoneal cavity, never suspended by mesentery]

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11
Q

Adult derivatives of foregut

A 
Esophagus
Stomach
Liver
Gallbladder
Pancreas
Upper duodenum
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12
Q

During stomach rotation, the dorsal mesogastrium enlarges, forming the ____ ____

A

Greater omentum

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13
Q

During stomach rotation:

The ventral border of the stomach moves to the ____

The dorsal border of the stomach moves to the _____

The left stomach surface becomes ____

The right side becomes ____

Overall a total rotation of ___ degrees occurs

A

Right

Left

Ventral

Dorsal

90

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14
Q

What is hypertrophic pyloric stenosis

A

Narrowing of the pyloric lumen obstructing food passage; the muscularis externa in the region hypertrophies forming a palpable mass at the right costal margin

Inability of sphincter muscles to relax d/t faulty migration of NCCs so ganglion cells of enteric nervous system are not properly populated

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15
Q

Symptoms of hypertrophic pyloric stenosis

Mother’s treated with what drug are at higher risk?

A

Symptoms: projectile non-bilious vomiting after feeding, fewer and smaller stools, failure to gain weight

Increased incidence in infants exposed to erythromycin

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16
Q

The embryonic liver begins as ______ from gut ______, which differentiates into heptocytes, bile ducts, and hepatic ducts

______ ______ differentiates into stromal cells, Kupffer, and stellate cells

A

Diverticulum; endoderm

Splanchnic mesoderm

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17
Q

The pancreas begins to form when an endodermal bud sprouts into the ___ _____.

_____ _____ and ventral pancreatic bud grow into ventral mesentery, whereas dorsal bud grows into dorsal mesentery

Pancreatic buds develop both ____ and ____ portions

A

Ventral mesentery

Cystic diverticulum

Endocrine; exocrine

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18
Q

What happens during the 5th month of gestation in terms of pancreas development? Which parts of the pancreas are associated with head, body, tail, and uncinate process?

What happens to the ventral pancreatic duct connection?

A

Ventral pancreas migrates around posteriorly and fuses with dorsal pancreas

The dorsal pancreas = head, body, tail

Ventral pancreas = uncinate process

Ventral pancreatic duct connection to duodenum is lost as it reconnects to dorsal pancreatic duct (may be retained as accessory pancreatic duct - 33% of population)

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19
Q

What congenital anomaly results when a single pancreatic duct is not formed, but rather remains as 2 distinct dorsal and ventral ducts? What condition are these patients more prone to?

A

Pancreas divisum

Patients prone to pancreatitis

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20
Q

What congenital anomaly results when the pancreas wraps around the duodenum and compresses it, causing duodenal obstruction or stenosis, bilious vomiting, and low birth weight?

A

Annular pancreas

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21
Q

Formation of bile by hepatic cells begins during week ___ of development. The bile duct lumen is first closed by opens via ________

A

12; recanalization

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22
Q

What is biliary atresia?

A

Obliteration of extrahepatic and/or intrahepatic ducts, which are then replaced by fibrotic tissues d/t acute or chronic inflammation

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23
Q

Symptoms, life expectancy, and treatment of biliary atresia

A

Progressive neonatal jaundice with onset soon after birth, white clay colored stool, dark urine,

12-19 month average survival, only tx is liver transplant

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24
Q

Spleen development begins during week ____ with mesenchymal condensation in the ____ _____, and the spleen actually forms in week ____

A

4; dorsal mesogastrium; 5

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25
Q

What germ layer is the spleen derived from?

A

Mesoderm

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26
Q

Midgut derivatives

A 
Lower duodenum
Jejunum
Ileum
Cecum
Appendix
Ascending colon
Proximal 2/3 of transverse colon
27
Q

During embryonic development, the size of the abdomen is limited. What does this mean for the development of the midgut structures? During what weeks does this occur?

A

The lengthening midgut must herniate out into the umbilicus at 6 weeks, then brought back in at 10 weeks when the abdomen is large enough to accomodate it

28
Q

When the midgut is pushed out into the umbilicus, it undergoes rotation.

The first rotation occurs at ___ days and is _____ degrees counterclockwise, which brings the cecum and future ascending colon to the ____ side.

The second rotation occurs at ___ days and is an additional ____ degrees counterclockwise, bringing the cecum to the ____ quadrant and ascending colon ____ to the duodenum

As the midgut returns to the abdominal cavity around ___ days, the cecum descends to the ____ quadrant carrying the ascending colon along with it so that the ascending colon ends up along the ____ side of the abdomen

A

50; 90; left

70; 90; LUQ; anerior

73; RLQ; right

[total of 270 degrees rotation bc another 90 degree rotation occurs during week 11 as midgut returns to abdomen]

29
Q

Summary of midgut rotation:

90 degrees CCW at week ____

+90 degrees CCW at week ____ (total 180)

+90 degrees CCW at week ___ (total 270)

A

6

10

11

30
Q

Why is midgut rotation significant in terms of viscera location?

A

Midgut rotation determines which structures are intraperitoneal, retroperitoneal, and secondarily retroperitoneal

31
Q

Following midgut rotation, most of the pancreas is considered secondarily retroperitoneal. Which part of the pancreas remains intraperitoneal?

A

The tail

32
Q

_______ is a gut malformation where there is herniation through the umbilicus including peritoneal covering

A

Omphalocele

33
Q

Increased risk of omphalocele occurs with trisomy ___ or ____

What are some other possible etiologies of omphalocele?

A

12;18

Etiologies:
-herniated bowel does not fully retract

  • lateral body wall folding and fusion fails to occur creating wall weakness allowing bowel to later herniate
  • CT of skin and hypaxial musculature of body wall does not form normally, creating wall weakness
34
Q

What gut malformation is characterized by herniation through the abdominal wall WITHOUT peritoneal covering?

A

Gastroschisis

35
Q

What gut anomaly is caused by failure of the yolk stalk (vitelline duct) connection to the midgut to regress and can lead to abdominal swelling, intestinal obstruction, bowel sepsis, and GI bleeding?

A

Meckel’s diverticulum

36
Q

Rule of 2’s concerning Meckel’s diverticulum

A

2% incidence

2x more common in males

2% have symptoms

Usually 2 ft proximal to terminal ileum

Usually 2 inches long

Usually presents at 2 years of age

37
Q

Compare non-rotation of midgut loop to reverse gut rotation

A

Non-rotation:
Midgut completes first 90 degree CCW rotation but does not do remaining 180 degree CCW rotation. Ends up with L sided colon and R sided small intestines

Reverse gut rotation:
Completes initial 90 degree CCW rotation but then does a 180 degree CW rotation. Transverse colon ends up posterior to duodenum

38
Q

______ = rolled up, twisted intestines that present as acute abdominal pain, vomiting, and GI bleeding. Increased risk of this with gut rotation anomalies

A

Volvulus

39
Q

During the 5-6th month of development, the lumen of intestines is temporarily obliterated because of ______ proliferation.

Later, _____ form as endodermal cells degenerate, reopening the lumen by the end of embryonic period.

A

Endodermal; vacuoles

40
Q

What congenital gut anomalies, commonly associated with trisomy 21, may occur if recanalization does not occur following temporary luminal occlusion during month 5-6 of development?

A

Duodenal stenosis - partial occlusion, usually involving horizontal and/or ascending parts

Duodenal atresia - complete occlusion

41
Q

Hindgut derivatives

A 
Distal 1/3 of transverse colon
Descending colon
Sigmoid colon
Rectum
Superior 2/3 of anal canal
42
Q

The ____ _____ partitions the cloaca into a dorsal anorectal canal and a ventral urogenital sinus; it develops fork-like extensions (infoldings) of the lateral cloacal walls that grow toward one another, dividing the cloaca into UG sinus and anal canal - which are opened to the exterior when the ____ _____ ruptures.

A

Urorectal septum

Cloacal membrane

43
Q

Compare the rectum to the anus in terms of germ layer and vasculature

A

Rectum = endoderm, inferior mesenteric aa. and vv. of hindgut

Anus = ectoderm, internal iliac aa. and vv.

44
Q

The anal rectal lumen is temporarily closed by an epithelial anal plug. _____ surrounding the anal canal proliferates forming anal pit with _____ walls.

The anal plug eventually opens via ______ death

A

Mesenchyme; ectodermal

Apoptotic

45
Q

How much of the anal canal is endodermal epithelium?

A

Superior 2/3 is endodermal epithelium

Lower 1/3 is ectodermal

46
Q

What is the named line dividing the origin of the hindgut and the anal pit?

A

Pectineal line

47
Q

An imperforated anus occurs d/t persistent anal membrane. Low, intermediate, or high distinction is relative to what anatomical structures?

A

Levator ani mm. and pelvic bony landmarks

48
Q

Defects due to abnormal urorectal septum can be detected based on the presence of ____ in the ____ of the female or the _____ of the male

A

Meconium; vagina; urine

49
Q

After stomach rotation, what innervates the ventral surface vs. the dorsal surface?

A

Ventral surface = left vagus n.

Dorsal surface = right vagus n.

50
Q

The upper anal canal develops from the _____ while the lower anal canal develops from the _____, which is an invagination of surface ectoderm caused by a proliferation of mesoderm surrounding the anal membrane

A

Hindgut; proctodeum

51
Q

Pancreatic islets consist of alpha, beta, and delta cells, which secrete glucagon, insulin, and somatostatin, respectively. These cells are derived from:

A. Mesoderm
B. Endoderm
C. Ectoderm
D. Neuroectoderm
E. Neural crest cells
A

B. Endoderm

52
Q

A 2-month-old baby with severe jaundice also has dark-colored urine (deep yellow) and white clay colored stool. Which of the following disorders might be suspected?

A. Esophageal stenosis
B. Annular pancreas
C. Hypertrophic pyloric stenosis
D. Extrahepatic biliary atresia
E. Duodenal atresia
A

D. Extrahepatic biliary atresia

53
Q

A 28 day old baby is brought to the physician because of projectile vomiting after feeding. Until this time, the baby has had no problems in feeding. On exam, a small knot is palpated at the right costal margin. Which of the following disorders might be suspected?

A. Esophageal stenosis
B. Annular pancreas
C. Hypertrophic pyloric stenosis
D. Extrahepatic biliary atresia
E. Duodenal atresia
A

C. Hypertrophic pyloric stenosis

54
Q

Which of the following arteries supplies foregut derivatives of the digestive system?

A. Celiac trunk
B. Superior mesenteric a.
C. Inferior mesenteric a.
D. Right umbilical a.
E. Intercostal a.
A

A. Celiac trunk

55
Q

The most common type of anorectal malformation is:

A. Imperforate anus
B. Anal agenesis
C. Anorectal agenesis
D. Rectal atresia
E. Colonic aganglionosis
A

C. Anorectal agenesis

56
Q

The simple columnar or cuboidal epithelium lining the extrahepatic biliary duct is derived from

A. Mesoderm
B. Endoderm
C. Ectoderm
D. Neuroectoderm
E. Neural crest cells
A

B. Endoderm

57
Q

A 4 day old baby boy has not defecated since coming home from the hospital even though feeding has been normal without any excessive vomiting. Rectal exam reveals a normal anus, anal canal, and rectum. However, a large fecal mass is found in the colon, and a large release of flatus and feces follows the rectal exam. Which of the following conditions would be suspected?

A. Imperforate anus
B. Anal agenesis
C. Anorectal agenesis
D. Rectal atresia
E. Colonic aganglionosis
A

E. Colonic aganglionosis

58
Q

Which of the following is derived from the midgut?

A. Appendix
B. Stomach
C. Liver
D. Pancreas
E. Sigmoid colon
A

A. Appendix

59
Q

A 3 month old baby girl presents with a swollen umbilicus that has failed to heal normally. The umbilicus drains secretions, and there is passage of fecal material through it at times. What is the most likely diagnosis?

A. Omphalocele
B. Gastroschisis
C. Anal agenesis
D. Ileal diverticulum
E. Intestinal stenosis
A

D. Ileal diverticulum

60
Q

The midgut loop normally herniates through the primitive umbilical ring into the extraembryonic coelom during week 6 of development. Failure of the intestinal loops to return to the abdominal cavity by week 11 results in the formation of

A. Omphalocele
B. Gastroschisis
C. Anal agenesis
D. Ileal diverticulum
E. Intestinal stenosis
A

A. Omphalocele

61
Q

Kupffer cells present in the adult liver are derived from

A. Mesoderm
B. Endoderm
C. Ectoderm
D. Neuroectoderm
E. Neural crest cells
A

A. Mesoderm

62
Q

The simple columnar and stratified columnar epithelia lining the lower part of the anal canal is derived from

A. Mesoderm
B. Endoderm
C. Ectoderm
D. Neuroectoderm
E. Neural crest cells
A

C. Ectoderm

63
Q

A baby born to a young woman whose pregnancy was complicated by polyhydramnios was placed in the ICU because of repeated vomiting containing bile. The stomach was markedly distended, and only small amounts of meconium had passed through the anus. What is the most likely dx?

A. Esophageal stenosis
B. Annular pancreas
C. Hypertrophic pyloric stenosis
D. Extrahepatic biliary atresia
E. Duodenal atresia
A

E. Duodenal atresia

GI personal (23 decks)

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