Lecture 1 - Development of the Digestive System Flashcards

1
Q

Foregut and hindgut form during which type of folding of the embryo

A

cranial and caudal folding

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2
Q

Endoderm from the dorsal yolk sac is incorporated into the embryo forming the

A

epithelial lining and the glands that are going to make up the inner most lining of our GI tract

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3
Q

the cranial fold with the oropharyngeal membrane as the hinge joint is incorporated as the embryologic ____

A

foregut

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4
Q

the caudal fold with the cloacal membrane as the hinge joint is incorporated as the emryologic __

A

hindgut

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5
Q

epithelial lining and glands of the GI tract

A

endoderm

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6
Q

During body folding (Week 4), endoderm from the ____ portion of yolk sac is incorporated into the embryo, forming the innermost lining of the primitive gut tube (the epithelial lining and glands of the G.I. tract).

A

dorsal

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7
Q

During lateral folding, yolk sac endoderm is incorporated as embryonic ___

A

midgut

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8
Q

forms the smooth muscle and connective tissue of the GI tract

A

Splanchnic (visceral) mesoderm

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9
Q

when we hear “peritoneum” think

A

abdomen

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10
Q

the serous membrane lining the abdominal cavity (parietal) & organs (visceral)

A

peritoneum

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11
Q

a double-layer of peritoneum that suspends an organ from the body wall
(can contain CT, fat, blood vessels, lymphatics, nerves)

A

mesentery

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12
Q

organs which are completely enclosed in mesentery and connected to wall via mesentery

A

Intraperitoneal

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13
Q

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

A

Retroperitoneal

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14
Q

somatic mesoderm or

A

parietal (body)

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15
Q

splanchnic mesoderm

A

visceral or dorsal (organ)

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16
Q

what is holding the midgut to the posterior body wall

A

dorsal mesentery

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17
Q

Formed via visceral mesoderm layers meeting and fusing in midline

A

dorsal mesentery

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18
Q

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

A

dorsal mesentery

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19
Q

Extends from lower end of esophagus to cloacal region of hindgut

A

dorsal mesentery

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20
Q

Divisions of dorsal mesentery:

(4)

A

Dorsal mesogastrium (greater omentum)

Mesoduodenum

Dorsal mesocolon

Mesentery proper

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21
Q

Dorsal mesentery in region of the stomach

A

Dorsal mesogastrium (greater omentum)

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22
Q

Dorsal mesentery in region of the duodenum

A

Mesoduodenum

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23
Q

Dorsal mesentery in region of the colon

A

Dorsal mesocolon

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24
Q

Dorsal mesentery of jejunal and ileal loops

A

mesentery proper

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25
Q

Derived from the septum transversum:

A

ventral mesentery

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26
Q

Mesodermal tissue that gives rise to central tendon of diaphragm and connective tissue in the liver

A

ventral mesentery

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27
Q

associate ventral mesentery with

A

foregut

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28
Q

Exists only in region of terminal esophagus, stomach, and upper part of duodenum

A

ventral mesentery

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29
Q

Liver grows in the mesenchyme of the septum transversum, dividing ventral mesentery into:
______– extends from lower portion of esophagus, stomach, & upper portion of duodenum to liver

____– extends from liver to ventral body wall

A

Lesser omentum – extends from lower portion of esophagus, stomach, & upper portion of duodenum to liver

Falciform ligament – extends from liver to ventral body wall

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30
Q

Free inferior margin of falciform ligament

Contains obliterated umbilical v.

A

Round ligament of the liver (Ligamentum teres hepatis)

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31
Q

Free margin of lesser omentum connecting duodenum & liver
Contains portal triad (bile duct, portal v., & hepatic a.)

A

Hepatoduodenual ligament

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32
Q

bile duct, portal v., & hepatic a. make up what

A

portal triad

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33
Q

enteric nervous system (no connecting to the brain, operates alone) is derived from

A

neuroectoderm neural crest cells

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34
Q

run from the pharynx and esophagus all the way down to the proximal half the the duodenum

A

foregut

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35
Q

run from the the distal half of the dueodenum all the way to the proximal 2/3 of the transverse colon

A

midgut

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36
Q

run from the distal 1/3 of the transverse colon all the way down out through the anus

A

hindgut

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37
Q

3 unpaired branches off the abdominal artery

A

celiac (trunk) artery
Superior mesenteric artery
inferior mesenteric artery

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38
Q

the 3 unpaired branches of the abdominal artery and what they supply
foregut?
midgut?
hindgut?

A

foregot - celiac trunk a.
midgut - superior mesenteric a.
hindgut - inferior mesenteric a.

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39
Q

Pharynx
Lower respiratory system
Esophagus
Stomach
Proximal ½ of duodenum (includes the pancreatic and bile duct papillae)
Associated organs (liver, gallbladder, biliary system, pancreas, spleen*)

A

Foregut Derivatives

40
Q

foregut derivative that includes the pancreatic and bile duct papillae)

A

proximal 1/2 of the duodenum

41
Q

Not a digestive organ but develops with foregut in mesoderm

A

spleen

42
Q

develops as the portion of the foregut immediately caudal to the pharynx

A

esophagus

43
Q

from the esophagus we get an endodermal outgrowth

A

respiratory diverticulum (or tracheobronchial diverticulum or lung bud)

44
Q

During week 4, ____ appears on ventral side of foregut (will become the trachea, respiratory tree & lungs)

A

a respiratory diverticulum

45
Q

Week 4: Appears as a fusiform dilation of the foregut.

A

stomach

46
Q

As the stomach enlarges, its ___ side expands faster than the other sides and will become the greater curvature. The ____side of the stomach will become the lesser curvature.

A

dorsal side - greater curve

Ventral side - lesser curve

47
Q

first rotation of the development of the digestive system

A

occurs at the stomach

48
Q

Stomach undergoes 90° clockwise rotation around its

A

longitudinal axis

49
Q

during stomach rotation, Ventral side (lesser curvature) ends up on the __, dorsal side (greater curvature) ends up on the ___

A

ventral lesser curve ends up on the right

dorsal greater curve ends up on the left

50
Q

As stomach rotates, the dorsal mesogastrium (dorsal mesentery of stomach) is carried to the left. This enlarges a space posterior to the stomach -

A

the omental bursa (lesser sac of peritoneum)

51
Q

a mesodermal proliferation within the dorsal mesogastrium

A

spleen primordium

52
Q

as the stomach rotates so does the spleen, Portion between spleen & dorsal midline swings to the left; fuses with peritoneum of posterior abdominal wall
Spleen remains ____

A

intraperitoneal

53
Q

2 ligaments of the spleen:
______– connected to body wall in the region of the left kidney
_____ – connected to stomach

A

Lienorenal ligament – connected to body wall in the region of the left kidney
Gastrolienal ligament – connected to stomach

54
Q

As a result of stomach rotation, dorsal mesogastrium extends inferiorly
Forms a double-layered sac that extends over the transverse colon & small intestine loops
The layers fuse to form a single (4 layer) sheet that hangs from the greater curvature of the stomach ____

A

the greater omentum

55
Q

first portion of the small intestine

A

duodenum

56
Q

As stomach rotates, the ____ becomes a C-shaped

Rotation, together with rapid growth of head of pancreas, swings ___(same) from midline to right side of abdomen

A

duodenum

57
Q

Duodenum and head of pancreas press against dorsal body wall, become fixed in

A

retroperitoneal position

58
Q

Dorsal mesoduodenum disappears completely except in region of ___, where small portion of duodenum retains its mesentery and is intraperitoneal

A

pylorus of stomach

59
Q

In the middle of the 3rd week, ____ appears at the distal end of the foregut as an outgrowth of the endodermal epithelium

A

liver primordium

60
Q

This outgrowth, known as ____, consists of rapidly proliferating cells that penetrate the septum transversum

A

the liver bud (hepatic diverticulum)

61
Q

mesodermal plate between pericardial cavity and stalk of the yolk sac

A

Septum transversum –

62
Q

Hepatic cells invade the septum transversum, the connection between the liver bud and foregut (duodenum) narrows, forming the

A

(common) bile duct

63
Q

A small ventral outgrowth from the bile duct

Forms

A

gallbladder and the cystic duct

64
Q

connection between the gallbladder and the bile duct is the

A

cystic duct

65
Q

The pancreas is formed by 2 buds:

These buds originate from the endodermal lining of the duodenum

A

a dorsal pancreatic bud & a ventral pancreatic bud

66
Q

Pancreas buds: The____ bud is within the dorsal mesentery; the __bud is an outgrowth of the bile duct

A

dorsal

ventral

67
Q

Pancreas: As the duodenum rotates, the ventral bud swings with it in the clockwise direction until aligning and fusing with the ___
Fusion of the Main and Accessory Pancreatic Ducts

A

dorsal bud

68
Q

Pancreas: Ventral bud comes to lie immediately below and behind the dorsal bud
___ bud: forms uncinate process and inferior part head of the pancreas
_____bud: forms all other parts of the pancreas

A

Ventral bud: forms uncinate process and inferior part head of the pancreas
Dorsal bud: forms all other parts of the pancreas

69
Q
Distal ½ of the duodenum (just after the major duodenal papilla)
Jejunum 
Ileum 
Cecum and appendix
Ascending colon 
Proximal 2/3 of the transverse colon
A

midgut derivatives

70
Q

axis of all midgut rotations

A

superior mesenteric a.

71
Q

Midgut forms a U-shaped loop around the superior mesenteric artery
The ____ is the temporary connection between the mid gut and yolk sac

A

vitelline duct

72
Q

midgut: Rapid elongation of gut & its mesentery results in formation of the

A

primary intestinal loop

73
Q
midgut: primary intestinal loop
\_\_\_\_\_limb becomes: 
Distal part of duodenum
Jejunum
Proximal ileum 
\_\_\_\_limb becomes: 
Distal ileum
Cecum 
Appendix
Ascending colon 
Proximal 2/3 of transverse colon
A

Cephalic limb becomes:
Distal part of duodenum
Jejunum
Proximal ileum

Caudal limb becomes: 
Distal ileum
Cecum 
Appendix
Ascending colon 
Proximal 2/3 of transverse colon
74
Q

Midgut: Due to rapid growth & expansion of liver, ___temporarily becomes too small to contain all the intestinal loops

A

abdominal cavity

75
Q

In the 6th–10th weeks, these midgut loops enter the extraembryonic cavity in the umbilical cord forming __ to account for not enough space for development

A

Physiological Umbilical Herniation

76
Q

1st midgut rotation: while things are being pushed out via the umbilical herniation, 90° Counterclockwise rotation (when viewed anteriorly) around the superior mesenteric artery
Initial growth and coiling of

A

the small intestine

77
Q

2nd midgut rotation: As the intestines return into the abdominal cavity, ____ rotation brings them to their final position during week 10

A

a 180° counterclockwise

78
Q

When ascending & descending colons obtain their final positions, their mesenteries press against peritoneum of

A

posterior abdominal wall

79
Q

the ascending & descending colons are permanently anchored in a

A

retroperitoneal position (secondarily retroperitoneal)

80
Q

The appendix, lower end of cecum, and sigmoid colon, however, retain their free mesenteries and are located

A

intraperitoneal

81
Q

fuses with posterior wall of greater omentum, but maintains its mobility (intraperitoneal)

A

Transverse mesocolon

82
Q

mesentery of the jejunoileal loops

Line of attachment extends from area where duodenum becomes intraperioneal, to the ileocecal junction

A

Mesentery proper

83
Q

___ line of attachment extends from the hepatic flexure of ascending colon to splenic flexure of descending colon

A

Transverse mesocolon’s line of attachment extends from the hepatic flexure of ascending colon to splenic flexure of descending colon

84
Q

midgut rotation summary

A

Total Rotation: 270° Counterclockwise

1st rotation: 90° CCW rotation while loop is in proximal umbilical cord
2nd rotation: 180° CCW rotation as intestines return to abdomen

Direction of rotation is assuming an anterior view
SMA is the axis of rotation

85
Q

Proliferation of endodermal lining completely occludes the gut tube during 6th week of development
Gut tube ____ is completed by 9th week of development

A

recanalization

86
Q

clinical correlation : A remnant of the vitelline (omphaloenteric) duct persists as a finger-like outpouching of the ileum ~40-60 cm from ileocecal junction
Diverticulum may contain pancreatic tissue/gastric mucosa that secretes acid, causing ulcers & bleeding
The most common GI malformation, occurring in 2% of population with a male predominance

A

Meckel’s (Ileal) Diverticulum

87
Q
Distal 1/3 of the transverse colon
Descending colon
Sigmoid colon
Rectum
Superior portion of the anal canal
A

hindgut derivatives

88
Q

Hindgut: A ____ grows inferiorly toward the cloacal membrane, dividing it into urogenital and anal membranes and partitioning the cloaca into the urogenital sinus (ventrally) and the anorectal canal (dorsally).

A

urorectal septum

89
Q

End of 7th week, ___membrane ruptures, creating anal opening for the hindgut & ventral opening for the urogenital sinus

A

cloacal

90
Q

Superior 2/3 of anal canal derived from ____ of hindgut

A

endoderm

91
Q

Inferior 1/3 of anal canal derived from invaginating ____around proctodeum

A

ectoderm

92
Q

Ectoderm in region of the anus proliferates & invaginates to create

A

anal pit

93
Q

The____degenerates

Establishes continuity between upper & lower parts of anal canal

A

anal membrane

94
Q

Junction between endodermal & ectodermal regions of anal canal is delineated by _____,

A

pectinate line

95
Q

in the anal canal, between the pectinate line and white line what is happening with epithelium

A

Epithelium changes from columnar to stratified squamous epithelium