Gut Rotation Flashcards

1
Q

What 3 germ layers are made due to cranial-caudal folding?

A

Mesoderm, Ectoderm, Endoderm.

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2
Q

Developmentally, what separates the abdominal cavity?

A

Septum transversum and pleuroperitoneal membrane.

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3
Q

From what type of mesoderm does the parietal layer of peritoneum arise?

A

Somatic mesoderm.

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4
Q

From what type of mesoderm does the visceral layer of peritoneum arise?

A

Splanchnic mesoderm.

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5
Q

How many layers and between which structures, are the peritoneal layers of the mesentery and omentum?

A

Mesentery: 2 peritoneal layers between organ and body wall
Omentum: 2 peritoneal layers between 2 organs

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6
Q

What organs make up the foregut?

A

Stomach, duodenum, liver, gallbladder, pancreas.

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7
Q

What organs make up the midgut?

A

Jejunum, ileum, cecum, appendix, ascending colon, first 2/3 transverse colon

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8
Q

What organs make up the hindgut?

A

Last 11/3 transverse colon, descending colon, sigmoid colon, rectum

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9
Q

Which organ is primary retroperitoneal?

A

Rectum.

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10
Q

Which organs are secondary retropertioneal?

A

Duodenum, pancreas, ascending colon, and descending colon

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11
Q

What role does Wnt-5a and Hox expression play in the primitive devlopment of the foregut and hindgut?

A

Initially, the gut tube is supposed to be the hindgut due to Wnt-5a signaling. But, Wnt antagonists repress hindgut identity in the cranial section of the gut tube. Transcription factors (Hhex, Sox2, Foxa2) then allow it to have a foregut identity. Cdx2 and Pdx1 cause Hox expression in the midgut –> hindgut and this makes the divisions of the small and large intestine and sphincters at the junctions

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12
Q

How is the lesser sac/omental bursa formed?

A

This occurs through rotation of the stomach. Barx1 gene causes dilation of the dorsal part of the foregut –> 90 degree rotation with duodenum = rotation of dorsal mesogastrium (lesser omentum) that is attached to liver == lesser sac/omental bursa behind stomach. Lesser omentum connects liver to stomach and liver is pulled to right side.

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13
Q

What is congenital pyloric stenosis?

A

This is hypertrophy of the pyloric sphincter which causes food to get backed up into the stomach and causes vomiting.

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14
Q

How is the liver developed?

A

hepatic/liver bud off foregut into –> septum transversum –pushed of –> peritoneum. Part not totally pushed out = bare area. Ventral mesentery = falciform ligament that connects liver to anterior abdominal wall. Hepatoduodenal ligament connects liver to duodenum and contains the portal triad.

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15
Q

How is the gallbladder formed?

A

Liver bud –> Cystic diverticulum –> gallbladder

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16
Q

How is the cystic duct formed?

A

Liver bud –> Cystic diverticulum –> cystic duct

17
Q

How is the pancreas formed?

A

1) Liver bud –> Cystic diverticulum –> Ventral pancreatic bud
2) Dorsal duodenum –> Dorsal pancreatic bud
3) Ventral bud rotates around duodenum and meets dorsal bud and then fuse = uncinate process

18
Q

How is the common bile duct formed?

A

Shared stalk of the liver and gallbladder –> common bile duct

19
Q

The duct of which part of the pancreas forms the main pancreatic duct? What happens to the other part?

A

The ventral pancreas. The dorsal pancreas duct regresses or makes accessory pancreatic duct

20
Q

Why is the spleen a mesodermal condensation and not an outgrowth of the gut tube?

A

The dorsal mesogastrium condenses to form the lienorenal and gastrolienal ligaments. This condensation allows for the spleen to mature. Spleen = mesodermal condensation?

21
Q

How are the intestines formed?

A

Cecum swells on intestinal loop –> loop rotates 90 degress counterclockwise –> small intestine herniates through umbilical opening –> body cavity grows –> small intestine re-enter abdominal cavity and push descending colon to left side and cecum and ascending colon to right side

22
Q

Which structure is the mesogastrium initially? And what does it become?

A

Lesser omentum/omental bursa. It becomes the greater ommentum.

23
Q

Why does the small intestine herniate through the umbilical opening during the development of the intestines?

A

Because the gut tube grows faster than the fetus can contain.

24
Q

What is Omphalocele?

A

Failure of midgut to return to abdominal cavity after herniation.

25
Q

What is Umbilical Hernia?

A

Failure of anterior abdominal muscles to join at the midline linea alba.

26
Q

What condition involves the failure of the vitelline duct and yolk sac to degenerate and remain attached at the umbilicus?

A

Meckel’s Diverticulum.

27
Q

What condition is characterized by the open connection between the intestinal lumen and outside via the umbilicus?

A

Umbilicoileal Fistula.

28
Q

What is Nonrotation?

A

When the gut loops fail to complete the final 180 degrees –> small and large intestine lie side by side

29
Q

What is the condition is characterized by the rotation of the midgut clockwise, instead of counter-clockwise?

A

Reverse Rotation.

30
Q

What is the cloaca?

A

It is the common opening for the hindgut and allantois

31
Q

How is the hindgut formed?

A

hindgut –> anorectal canal and allantois –> urogenital sinus and they –separated by–> urorectal septum expansion –fuses with–> proctodeum –> urogenital and anal membranes (from cloacal membrane)

32
Q

What is the anal pit?

A

An ectodermal invagination into anorectal canal.

33
Q

What is the pectinate line in the adult?

A

The boundary between the ectodermal and the endodermal derived tissue within anal canal