Digestive System Embryology Flashcards

1
Q

In what week of development does gastrulation begin?

A

The third week of development

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2
Q

What marks the beginning of gastrulation?

A

The formation of the primitive streak on the surface of the epiblast

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3
Q

How many of the germ layers contribute to the formation of the digestive system?

A

All three germ layers

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4
Q

In the GI tract what does the ectoderm form?

A

Neural crest cells from the neuroectoderm become neurons of the enteric nervous system

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5
Q

In the GI tract what does the mesoderm form?

A

Connective tissues, muscular components, and peritoneal components

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6
Q

In the GI tract what does the endoderm form?

A

Epithelium of GI tract and parenchyma of glands

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7
Q

When does the gut tube initially form?

A

The 4th week of development

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8
Q

What are parenchyma?

A

the specific cells of a gland or organ held together by connective tissue called the stroma

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9
Q

The stroma of the glands of the GI tract is derived from what?

A

The visceral mesoderm

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10
Q

Describe neurulation?

A

The trilaminar embryonic disc forms the neural plate that rolls up into a tube to from the brain and spinal cord

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11
Q

The mesoderm layer of which holds the neural tube and gut tube together splits into two layers during the 3rd and 4th week and are called what?

A

Visceral (splanchnic) and parietal (somatic) layers

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12
Q

What does the visceral (splanchnic) layer of the mesoderm do in the 3rd and 4th week of development?

A

Rolls ventrally, and is intimately connected to the gut tube

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13
Q

What does the parietal (somatic) layer of the mesoderm do in the 3rd and 4th week of development?

A

Together with the overlying ectoderm, forms the lateral body wall folds, which move ventrally and meed in the midline to close the ventral body wall

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14
Q

What does the vitelline duct and yolk sac eventually get incorporated into?

A

The umbilical cord

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15
Q

When does the yolk sac typically degenerate?

A

Around 2 to 3 months of development

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16
Q

By the 4th week of development closure of the ventral body wall is complete except where?

A

At the connecting stalk

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17
Q

By the 4th week of development closure of the gut tube is complete except where?

A

At the vitelline duct (yolk sac)

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18
Q

What are the three regions of the gut tube?

A

Foregut, midgut, and hindgut

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19
Q

Define the each end of the foregut in the 4th week of development.

A

Oropharyngeal membrane to the liver outgrowth

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20
Q

When does the oropharyngeal membrane rupture?

A

The 4th week

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21
Q

What is connected when the oropharyngeal membrane ruptures?

A

The oral cavity and the primitive gut

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22
Q

Define each end of the midgut in the 4th week of development.

A

Begins caudal to liver and extends to proximal 2/3 of transverse colon

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23
Q

Define each end of the hindgut in the 4th week of development.

A

From distal 1/3 of transverse colon to cloacal membrane

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24
Q

When does the cloacal membrane break down?

A

The 7th week of development

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25
Q

What is mesentary?

A

A double layer of peritoneum that encloses an organ and connects it to the body wall

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26
Q

What is peritoneum?

A

Thin serous membrane that lines walls of abdominal cavity

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27
Q

Define intraperitoneal.

A

Organs which are completely enclosed in mesentary and connected to wall via mesentary

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28
Q

Define retroperitoneal.

A

Organ that lies against posterior body wall and is covered with peritoneum on an anterior surface only

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29
Q

Define serous membrane.

A

Membrane that lines body cavities (i.e. peritoneal cavity) and produces thin watery lubricating fluid (serous fluid)

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30
Q

Define dorsal mesentary.

A

This is mesentary that is formed via visceral mesoderm layers meeting and fusing in midline

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31
Q

At the fifth week of development what is suspended in the dorsal mesentary?

A

The caudal part of the forgut, the midgut, and major part of the hindgut are suspended from the posterior body wall via the dorsal mesentary

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32
Q

At the fifth week of development where does the dorsal mesentary extend from? (what to what)

A

The lower end of esophagus to cloacal region of hindgut

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33
Q

What are the divisions of the dorsal mesentary?

A

Dorsal mesogastrium, mesoduodenum, dorsal mesocolon, mesentary proper

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34
Q

Where is the dorsal mesogastrium located and what is it also called?

A

Located in dorsal mesentary region of the stomach and is also called the greater omentum

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35
Q

Where is the mesoduodenum located?

A

Dorsal mesentery region of the duodenum

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36
Q

Where is the dorsal mesocolon located?

A

Dorsal mesentery in region of the colon

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37
Q

Where is the mesentary proper located?

A

Dorsal mesentery of jejunal and ileal loops

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38
Q

What is the ventral mesentary derived from?

A

The septum transversum

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39
Q

The central tendon of the diaphragm and connective tissue in the liver is derived from what primary tissue?

A

The mesodermal tissue

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40
Q

The ventral mesentery exists only in what 3 regions?

A

Terminal esophagus, stomach, and upper part of duodenum

41
Q

Specifically what is the central tendon of the diaphragm derived from?

A

A portion of the septum transversum, consisting of densely packed mesoderm

42
Q

The developing liver grows in what?

A

The mesenchyme of the septum transversum

43
Q

What does the developing liver divide the ventral mesentary into?

A

The lesser omentum and the falciform ligament

44
Q

Where does the lesser omentum extend?

A

Extends from lower portion of esophagus, stomach, and upper portion of duodenum to liver

45
Q

Where does the falciform ligament extend from?

A

Extends from liver to ventral body wall

46
Q

What is the round ligament of the liver?

A

This is the free inferior margin of falciform ligament and contains obliterated umbilical v.

47
Q

What is the hepatoduodenual ligament?

A

This is the free margin of lesser omentum containing duodenum and liver, and contains portal triad

48
Q

What is the portal triad?

A

Bile duct, portal v., and hepatic a.

49
Q

What is the epiploid foramen of Winslow?

A

This is an opening that connects omental bursa (lesser sac) with the rest of peritoneal cavity (greater sac)

50
Q

What major artery supplies the foregut?

A

Celiac (trunk) aftery

51
Q

What major artery supplies the midgut?

A

Superior mesenteric artery

52
Q

What major artery supplies the hindgut?

A

Inferior mesenteric artery

53
Q

At the 4th week of development what does the foregut divide into?

A

Respiratory primordium (ventral), and esophagus (dorsal)

54
Q

The upper 2/3 of the esophagus has what kind of muscle and is innervated with what?

A

Striated muscle and Vagus n.

55
Q

The lower 1/3 of the esophagus has what kind of muscle and is innervated with what?

A

Smooth muscle and splanchnic plexus

56
Q

What is the fusiform dilation of the foregut (4th week)?

A

The stomach

57
Q

How does the stomach “move” during its development?

A

It rotates along longitudinal andanteroposterior axis

58
Q

The Left Vagus nerve eventually innervates what part of the stomach?

A

The anterior wall

59
Q

The Right Vagus nerve eventually innervates what part of the stomach?

A

The posterior wall

60
Q

During stomach development how far in degrees does the stomach rotate?

A

90 degrees

61
Q

What leads to the development of the greater and lesser curvatures of the stomach?

A

The original posterior wall grows faster than the original anterior portion

62
Q

Where is the pylorus of the stomach?

A

Caudal part, towards the end

63
Q

Where is the cardia of the stomach?

A

Cephalic part, towards the beginning

64
Q

What is the omental bursa?

A

A space created behind stomach from the dorsal mesogastrium being pulled to the left

65
Q

What is the lienorenal ligament?

A

This connects the spleen to the body wall in the region of the left kidney

66
Q

What is the gastrolinal ligament?

A

This ligament connects the spleen to the stomach

67
Q

What is the duodenum formed from?

A

The terminal part of the foregut and cephalic part of the midgut. So simply the foregut and midgut

68
Q

The duodenum and head of pancreas eventually end up in what peritoneal position?

A

They become fixed in a retroperitoneal position

69
Q

What and where is the duodenal cap?

A

This is a small portion of the duodenum near the pylorus of stomach and is intraperitoneal

70
Q

Where does the blood supply of the duodenum come from?

A

Both the celiac a. and superior mesenteric a.

71
Q

When and how does the liver begin to form?

A

At the middle of the third week a liver bud appears.

72
Q

What does the liver bud consist of and where do they penetrate?

A

Rapidly proliferating cells that penetrate the septum transversum

73
Q

What forms the (common) bile duct?

A

The connection between the liver bud and foregut

74
Q

A small ventral outgrowth is formed by the bile duct and gives rise to what?

A

The gallbladder and the cystic duct

75
Q

The pancreas is formed by what two things?

A

The dorsal pancreatic bud, and a ventral pancreatic bud

76
Q

Where is the dorsal bud of the pancreas originally found?

A

Within the dorsal mesentery

77
Q

Where is the ventral bud of the pancreas originally located?

A

Close to the bile duct

78
Q

The ventral bud of the pancreas eventually becomes what?

A

The uncinate process and inferior part of the head of the pancreas

79
Q

What is the duct of Wirsung?

A

The main pancreatic duct

80
Q

What is the major duodenal papilla?

A

This is where the main pancreatic duct and bile duct enter the duodenum

81
Q

What is the Santorini of the pancreas?

A

An accessory pancreatic duct

82
Q

When does insulin start to secret from the pancreas?

A

Approximately 5th month of development

83
Q

What are the pancreatic islets (islets of Langerhans)?

A

They are part of the hormonal component of the pancreas

84
Q

In an adult where does the midgut extend?

A

Begins just distal to the entrance of bile duct into duodenum and terminates at junction of proximal 2/3 of transverse colon with distal 1/3

85
Q

What are the three parts of the cephalic limb of the primary intestinal loop?

A

Distal part of teh duodenum, jujunum, and part of the ileum

86
Q

What are the five parts of the caudal limb of the primary intestinal loop?

A

Lower portion of the ileum, cecum, appendix, ascending colon, proximal 2/3 of transverse colon

87
Q

What is the physiological umbilical herniation?

A

This is where the abdominal cavity becomes too small for the growing intestinal loops so they herniate into an extraembryonic cavity in the umbilical cord

88
Q

What are the three most common vitelline duct abnormalities?

A

Meckel diverticulum, vitelline cyst, and vitelline fistula

89
Q

The ascending and descending colons are permanently anchored in what position?

A

Retroperitoneal position (secondarily retroperitoneal)

90
Q

The appendix, lower end of the cecum and sigmoid colon retain their free mesenteries so they are in what position?

A

Intraperitoneal

91
Q

What is the mesentery proper?

A

Mesentery if the jejunoileal loops

92
Q

The hindgut gives rise to what?

A

Distal 1/3 of transverse colon, sigmoid colon, rectum, and upper part of anal canal

93
Q

The endoderm of hindgut forms what?

A

internal lining of bladder and urethra

94
Q

What artery supplies the hindgut?

A

Inferior mesenteric artery

95
Q

What is the cloaca?

A

An endoderm-lined cavity covered at its ventral boundary by surface ectoderm

96
Q

What is the urorectal septum?

A

Wedge of mesoderm that separates the region between the allantois and hindgut

97
Q

What is the proctodeum

A

AKA the anal pit and is an ectodermally-lined pit in the terminal portion of the hindgut that invaginates to form the lower 1/3 of the anal canal

98
Q

What is the pectinate line?

A

This line divides the part of the anal canal in halves derived from the anal pit and the hindgut