Gastrointestinal tract Flashcards

1
Q

What leads to the formation of the endodermal gut tube?

A

Embryonic folding (amnion folds around the embryo)

Change in shape of the yolk sac

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2
Q

What is the coelomic cavity, when does it form?

A

The space between the gut tube and somatic mesoderm

Forms in folding of the embryo as parietal mesoderm fuses

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3
Q

What is the cavity outside of the coelomic cavity?

A

Amniotic cavity

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4
Q

What mesoderm makes up the gut tube?

A

Splanchnic (visceral) mesoderm

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5
Q

What joins to the visceral/splanchnic mesoderm to the parietal mesoderm?

A

Dorsal mesentery

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6
Q

What is the origin of the epithelial lining of the gut tube?

A

Endoderm

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7
Q

At the rostral/caudal ends of the gut tube, what does the endoderm interface with, what are these areas called?

A

Ectoderm

Buccopharyngeal membrane (rostral)

Cloacal membrane (caudal)

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8
Q

Is there a ventral mesentery? What level at?

A

Yes

At the level of the stomach and liver

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9
Q

What develops within the ventral mesentery?

A

The liver

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10
Q

What does the ventral mesentery end up as?

A

The lesser omentum and falciform ligament

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11
Q

Describe the blood supply to each gut region?

A

The foregut, is supplied by the coeliac artery.

The midgut, is supplied by the superior mesenteric artery.

The hindgut, is supplied by the inferior mesenteric artery.

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12
Q

What mesentery does the stomach have?

A

Both dorsal and ventral

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13
Q

What is the initial shape of the stomach?

A

Fusiform

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14
Q

What is the movement of the stomach as it enlarges?

A

Rotates 90 degrees

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15
Q

What does the rotation of the stomach do the vagus nerves?

A

Moves the left vagus nerve anterior and right vagus posterior

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16
Q

What does the second rotation of the stomach achieve?

A

Upper cardiac part moves to the left side and the pyloric lower part moves to the right

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17
Q

What is the lesser sack continuous with the greater sack through?

A

Epiploic foramen

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18
Q

What does the dorsal mesentery become at the stomach?

A

Greater omentum

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19
Q

What does the liver form from?

A

Diverticulum from the gut tube

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20
Q

Where does the initial liver bud grow into?

A

Mesoderm of the septum transversum

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21
Q

What does the mesoderm pulled along by the liver bud form?

A

Lesser omentum and falciform ligament

22
Q

What does the caudal part of the liver diverticulum form?

A

Gall bladder

23
Q

What happens to the cranial part of the liver diverticulum?

A

Undergoes repeated branching to form first a major left and right branch and then a series of smaller branches to generate the liver cords of hepatocytes and vascular sinuses.

24
Q

What lies between developing hepatocytes?

A

Bile cannaliculi

25
Q

What is the remnants of the umbilical vein?

A

Ligamentum teres

26
Q

What is the remnants of the ductus venosus?

A

Ligamentum venosum

27
Q

Where are the ligamentum teres and ligamentum venosum found?

A

Within the falciform ligament

28
Q

What does the pancreas develop from?

A

Two buds

29
Q

What are the two pancreas buds?

A

A ventral bud from the liver diverticulum and a dorsal bud.

30
Q

What pancreas bud comes from the liver diverticulum?

A

Ventral

31
Q

How does the pancreas form one organ?

A

As the gut rotates, the ventral bud moves behind the duodenum and fuses with the dorsal bud to form the hook-shaped pancreas.

32
Q

What parts of the adult pancreas do the dorsal and ventral buds form?

A

The ventral bud forms the uncinate process of the adult pancreas, while the dorsal bud forms most of the head body and tail.

33
Q

Is the pancreas intra or retroperitoneal?

A

Pancreas is secondarily retroperitoneal except for the tail which is intraperitoneal

34
Q

Why is the pancreas (mainly) secondarily retroperitoneal?

A

Structures initially were suspended in mesentery and later migrated behind the peritoneum during development

Mesentery of pancreas fuses with the posterior abdominal wall

35
Q

What is hypothesised to cause gut rotations?

A

Nodal flow asymmetry - asymmetric localisation of nodal gene expression and consequent asymmetric development of the body.

36
Q

What suspends the midgut?

A

Dorsal mesentery

37
Q

What means the gut has to rotate around an axis?

A

It is fixed by the superior mesenteric artery and vitelline duct

38
Q

What does growth of the gut tube lead to?

A

Growth exceed the capacity of the cavity it herniates through the anterior abdominal wall to form a membranous sac of gut in the umbilical trunk.

39
Q

What causes formation of jejunal-ilial folds?

A

Rapid elongation

40
Q

As the gut herniates what does it do?

A

Rotates 90 degrees anti-clockwise

41
Q

What happens to the herniated, rotated gut tube after some time?

A

Retracts back into abdominal cavity

42
Q

When the gut tube returns to the abdominal cavity, what does it do?

A

Rotates a further 180 degrees anti-clockwise

43
Q

What is the total rotation of the gut tube (size and direction)?

A

270 degrees anti-clockwise

44
Q

What does the hindgut consist of?

A

Distal 1/3 of transverse colon

Descending colon, sigmoid colon and rectum

Superior part of anal canal

45
Q

Is the colon retro/intraperitoneal, how?

A

Secondarily retroperitoneal, mesentery fuses with posterior abdominal wall

46
Q

How is the urogenital system separated from the gut?

A

Urorectal septum grows between the two cavities.

47
Q

What does splanchnic mesoderm form?

A

Visceral peritoneum (surrounds gut), muscle and connective tissue around lining

48
Q

What does somatic mesoderm form?

A

Parietal peritoneum (lines abdominal cavity) connective tissue of abdominal wall

49
Q

What is a hiatal hernia?

A

Hiatal hernia is a type of hernia in which abdominal organs (typically the stomach) slip through the diaphragm into the middle compartment of the chest

50
Q

What does intraembryonic coelom between 2 layers of mesoderm form?

A

Peritoneal cavity (splits lateral plate mesoderm into 2 layers)

51
Q

Gut diverticula undergo branching morphogenesis to form the ….

A

Liver, pancreas and lungs