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GI System > GI embryo flashcards > Flashcards

GI embryo flashcards

1
Q

what happens on day 16?

A

gastrulation (epiblast forms the 3 layers:epi, meso and endoderm)

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2
Q

what layers contribute to the gut tube?/GI system?

A

All 3: endoderm, mesoderm, ectoderm

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3
Q

What does the endoderm form?

A

the epithelial lining from pharynx to the upper 2/3s pf the anal canal, and the epithelium of all the glands/organs that are extensions of the gut tube

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4
Q

What are the GI accessory organs/glands that form from the gut tube?

A

submandibular and sublingual glands, liver, pancreas and gall bladder

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5
Q

What does the mesoderm form in the GI system?

A

connective tissue, mesentary and smooth muscle

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6
Q

What does the ectoderm form in the GI system?

A

the nerves; and the epithelium in mouth and lower 1/3 of anal canal

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7
Q

what is Hirshsprung disease?

A

failure of the ectoderm’s neural crest cells to migrate to the caudal 1/3 of the colon–> resulting in megalocolon

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8
Q

how does the endoderm end up lining the inside of the gut tube?

A

folding of the embryo

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9
Q

what stays outside when the folding occurs?

A

the yolk sac and the allantois

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10
Q

remind me, what is the allantois and the yolk sac?

A

the allantois is a diverticulum of the gut tube near the cloaca, and becomes (mostly) the urinary bladder in the adult, the other part eventually becomes part of the umbilical cord by joining the vitilline duct (yolk sac stalk) and blood vessels but is initially on its own (partially in and out of the embryo); the allantois does nothing in humans and will degrad to wharton’s jelly in the umbilical cord with the vitilline duct; the yolk sac is thought to provide nutrients to the embro initially and is a place where gonadal stem cells reside for a while before going to their respective places

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11
Q

as an embryo, can fluids pass through the gut tube?

A

not initially, the tubes are blind-ended at the mouth and anus until the 5th and 7th weeks, respectively

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12
Q

what are the different portions of the gut tube?

A

foregut, midgut, hindgut

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13
Q

what part is the foregut in the embryo? The adult?

A

from the buccopharyngeal membrane through the pharynx to the liver bud; in the adult it goes from the pharynx to the 2ndpart of the doudenum (including the pancreas, liver and gall bladder

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14
Q

how is blood/nutrients mainly supplied to the foregut?

A

by the celiac artery

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15
Q

what part is the midgut of the embryo and the adult?

A

the lower 1/2 of the duodenum to 2/3 of the transverse colon; parts 3 nd 4 of the duodenum, small intestine, cecum, appendix, ascending and the rt. 2/3s of the transverse colon

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16
Q

what vessel supplies the midgut?

A

the superior mesenteric artery

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17
Q

what part of the gut tube in the embryo and adult form the hindgut?

A

lower 1/3 of the transverse colon to the cloacal membrane; the left 1/3 of the transverse colon to the upper 2/3s of the anal canal

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18
Q

what vessel supplies the hindgut?

A

the inferior mesenteric artery

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19
Q

how does the stomach develop and end up in it’s position with an anterior and posterior vagal trunk sandwiching it?

A

the dorsal aspect grows faster than the ventral surface, it rotates 90 deg around the vertical axis so that the rt vagus nerve becomes posterior and the left vagus nerve becomes anterior, the stomach also shifts to the left and rotates 45 deg in a coronal plane

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20
Q

What is formed due to the pulling of the dorsal mesentery as the stomach positions itself?

A

the lesser sac

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21
Q

what is the greater omentum formed from and how did it get there?

A

stretched out from the dorsal mesentery as the stomach rotated– it hangs off the greater curvature of the stomach and posterior wall

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22
Q

what is the general shape of the duodenum and how did it get that way?

A

it is a “c” shape– it is pulled superiorly and to the rt as the stomach rotates and the pancreas grows

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23
Q

what is the blood supply to the duodenum?

A

anastamoses from both the celiac and the superior mesenteric arteries

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24
Q

during the 2nd month, the lumen of the duodenum is obliterated, but then recanalized by apoptosis- if not recanalized a person will have what problem?

A

duodenal atresia or stenosis if partially blocked, or perhaps biliary atresia if the main pancreatic duct is blocked

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25
Q

what is the radiographic sign of duodenal atresia?

A

double bubbles separated from eachother by the pyloric sphincter

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26
Q

what happens if the main duct is blocked during recanalization?

A

Extrahepatic biliary atresia, a child may present with jaundice, dark urine and light stools

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27
Q

where do accessory abdominal organs develop from?

A

2nd part of the duodenum (where the main (with common bile duct material)and accessory pancreatic ducts enter the duodenum)

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28
Q

how does the liver develop?

A

grows out from the duodenum and enters the ventral mesentery and the septum transversum

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29
Q

what does mesenteric liver tissue become?

A

hematopoeitic, Kupffer and connective tissue cells (does hematopoeisis from weeks 8-30)

30
Q

how does the pancreas form?

A

from two endodermal outgrowths (dorsal and ventral); the ventral swings around posteriorly and joins the dorsal bud

31
Q

what part does the ventral pancreatic bud become?

A

the inferior part of the head and uncinate process

32
Q

what does the dorsal bud become?

A

the superior part of the pancreatic head, the neck, body, and tail

33
Q

the main pancreatic ampulla/duct arises from which pancreatic buds?

A

the entire ventral and the distal part of the dorsal bud

34
Q

the accessory pancreatic duct/ampulla comes from which part of the pancreatic buds (if present)?

A

the proximal portion of the dorsal bud.

35
Q

which other duct empties into the main pancreatic duct?

A

the common bile duct from the gallbladder’s bile duct and the hepatic duct

36
Q

at about week 6, what part of the gut tube herniates through the umbilical ring?

A

the midgut, which is attached to the SMA (superior mesenteric artery)

37
Q

When the midgut herniates initially, how much does it rotate?

A

90 deg around the SMA

38
Q

when the midgut enters the abdominal cavity again, how much more does it rotate? How much total?

A

180 deg; 270 deg total

39
Q

the jejunum enters 1st and the cecal bud enters last, but what else needs to happen to be in anatomical position?

A

the cecum needs to drop from the RUQ to the LRQ

40
Q

what is the end of the hindgut called?

A

the cloaca

41
Q

how does the cloaca become the urogenital sinus and the rectoanal canal?

A

a urorectal septum divides it, also making the cloacal membrane into an anal and urogenital membrane

42
Q

if the hindgut only makes up the proximal 2/3 of the anal canal, what creates the lower 1/3?

A

invagination of the surface ectoderm

43
Q

what is another word for the anal pit?

A

the proctodeum

44
Q

what is the pectinate line?

A

it is the division between ectoderm and endoderm

45
Q

what type of epithelium is found at the pectinate line?

A

columnar epi above, stratified squamous (non keratinized) below

46
Q

what is the bl supply at the pectinate line?

A

superior rectal artery abv, middle and inf rectal artery blw

47
Q

what is the lymph drainage at the pectinate line?

A

internal iliac and inf mesenteric lymph nodes abv, superficial inguinal lymph blw

48
Q

what is the innervation round the pectinate line?

A

hypogastric plexus abv, inf rectal nerve branching from the pudendal nerve blw

49
Q

what is the bl drainage around the pectinate line?

A

sup rectal vein abv, middle and inf rectal vein below

50
Q

what happens when the vitilline duct persists?

A

you have a meckel’s diverticulum

51
Q

what ectopic does a Meckel’s diverticulum usually contain and why is this bad?

A

ectopic gastric and pancreatic tissue, HCL is produced and you have ulceration and bleeding

52
Q

where are Meckel diverticulums normally found?

A

about 2 feet from the iliocecal valve

53
Q

how big are they?

A

2 inches long

54
Q

in whom does it occur more frequently?

A

2x more in males

55
Q

how frequently does it occur?

A

2% of the population affected

56
Q

when does it normally present?

A

at 2 yo

57
Q

What else is associated with vitilline persistence?

A

vitilline cysts and fistulas

58
Q

what happens when the allantois remains patent?

A

you have a urachal fistula (with urine leaving the bladder) or at least a urachal cyst

59
Q

why are respiratory and esophageal problems often occur together?

A

because the lung bud is created from the same endoderm that forms the esophagus

60
Q

what happens when there is incomplete separation of the esophagus and trachea?

A

you get polyhydraminos bc the fetus cannot swallow; this is called an esopha

61
Q

what are the birth defects in women who take progesterone-estrogen contraceptives during gestation?

A

VACTERL: vertebral, anal, cardiac, tracheal, esophageal, renal, limb abnormalities

62
Q

what is it when the pancreas wraps around the entire duodenum during development?

A

the Annular pancreas can cause duodenal stenosis

63
Q

define gastroschisis

A

guts come out of abdominal cavity into the umbilical cord with an associated rupture of the amnion

64
Q

the duodenum is behind what structure?

A

the transverse colon

65
Q

define omphalocele

A

failure of the midgut to return to the abdominal cavity – still covered by amnion

66
Q

define umbilical hernia

A

failure of the umbilical wall and intestines are covered by skin/subcutaneous tissue

67
Q

malrotation problems:

A

non-rotation, reversed rotation (situs inversis) and subhepatic cecum and appendix

68
Q

what causes a volvulus and what is it?

A

it is a twisting/cutting off of circulation to a portion of the gut generally because of mobile segments of the intestines move

69
Q

what might happen when there are problems with urorectal septum formation?

A

rectourethral fistula, rectovaginal fistula, imperforate anus, persistent cloaca rectocloacal fistula, etc

70
Q

problems: intestinal duplication

A

=rare

71
Q

problem: anal stenosis

A

=hindgut anomaly

GI System (1 decks)

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