Embryology-08-Gastro-Intestinal System Dev.

Front 1

formation of primitive gut by what

Back 1

transverse fold during 4th week

Front 2

gut divided into what

Back 2

foregut, midgut, hindgut

Front 3

end of primitive hindgut

Back 3

cloaca

Front 4

separates cloaca from proctodeum

Back 4

cloacal membrane

Front 5

what is proctodeum

Back 5

pit like depression on outside of embryo

Front 6

cloaca becomes

Back 6

rectum, anal canal, urethra

Front 7

cloacal membrane does what

Back 7

later breaks down – establishes connection to outside

Front 8

attaches gut to posterior body wall?

Back 8

dorsal mesentery

Front 9

connects only foregut to anterior body wall

Back 9

ventral mesentery

Front 10

primitive gut lined with, and supported by – tissues?

Back 10

lined with endoderm, supp. by splanchnic mesoderm

Front 11

endoderm forms what in GI tract

Back 11

tissue lining GI tract and its outgrowths (including lungs, airways)

Front 12

endoderm also forms what structures that open to GI?

Back 12

parenchyma=secretory cells=liver, GB, pancreas &lining

Front 13

forms smooth muscle and conn. tissue of primitive gut?

Back 13

mesoderm

Front 14

connects primitive gut to yolk sac, obliterates when?

Back 14

vitelline duct, gone by 5 – 6 week

Front 15

where does the vitelline duct connect

Back 15

midgut at terminal ileum (so remnants assoc. with term. ileum: MECKELS DIVERTICULUM!!

Front 16

vitelline duct remnants in what % of pop, M vs. F?

Back 16

more in males, in about 2% of people

Front 17

Types of vitelline duct remnants:

Back 17

fistula=Meckels D, cyst, or open fistula

Front 18

why might diverticula and cysts develop on mesentery side of gut

Back 18

between notochord and endoderm, because endoderm very close to gut, so small bits may stick together during dev.

Front 19

foregut structures

Back 19

respiratory tree (larynx – alveoli), esophagus, stomach, duodenum, liver, GB, pancreas

Front 20

foregut development event summary

Back 20

laryngotracheal diverticulum, gastric dilatation, foregut occulusion proximal and distal to the gastric dilatation (makes dilatation of gut), subsequent recanalization, elongation of esophagus, moving stomach to abdomen, rotation of stomach, differential growth of stomach, outgrowth of liver, GB, pancreas.

Front 21

if laryngotracheal diverticulum doesn’t form correctly, what happens

Back 21

fistula (polyhydramnios)

Front 22

if foregut recanalization doesn’t occur properly, result?

Back 22

stenosis or atresia in duodenum

Front 23

if esophagus doesn’t elongate properly, what happens

Back 23

stomach can’t move - abdomen, interferes w/ lung dev.

Front 24

rotation of the stomach does what

Back 24

dorsal border and mesentery to left side

Front 25

dorsal mesentery forms what?

Back 25

greater omentum, gastrosplenal, splenorenal ligaments

Front 26

ventral mesentery forms what

Back 26

liver coverings & ligaments, and lesser omentum

Front 27

midgut forms

Back 27

duodenum past comm. bile duct, jej/ileum,cecum, appendix, asc. colon, 2/3 trans. colon

Front 28

which wall of the stomach grows faster?

Back 28

dorsal wall

Front 29

when does the stomach rotate 90 degrees clockwise around the longitudinal axis

Back 29

during 7th week

Front 30

what does the rotation produce?

Back 30

lesser sac

Front 31

where are the vagus nerves after the rotation?

Back 31

left on anterior stomach, right on posterior

Front 32

how does the stomach come to be in its adult orientation

Back 32

next rotation is of stomach and duodenum about ventrodorsal axis, pulling end of stomach upwards

Front 33

dorsal mesentery hanging from greater curve now called?

Back 33

greater omentum

Front 34

in umbilicus, which direction does the herniation of the midgut loop rotate?

Back 34

counterclockwise

Front 35

which half of the midgut elongates?

Back 35

proximal half

Front 36

elongation of the midgut creates?

Back 36

coils of small intestine

Front 37

how many degrees does the midgut rotate

Back 37

270 in total

Front 38

after midgut rotation complete, what happens?

Back 38

loop moves into gut, rotates 180 degrees counterclockwise, then proximal end of intestine rotates another time 180 degrees

Front 39

what does the final rotation accomplish?

Back 39

duodenal-jejunal junction to adult location

Front 40

where is cecum following return of the hernia to the abdomen?

Back 40

initially subhepatic

Front 41

how does cecum end up in right iliac fossa?

Back 41

further gut elongation grows the ascending colon

Front 42

if there is a malrotation – what occurs?

Back 42

small intestine will be on one side, large intestine on other – diagnostic problems, confusing for examination & surgery

Front 43

what % of population have malrotation

Back 43

5%

Front 44

failure of midgut to return to gut – name?

Back 44

omphalocele – intestines within umbilical cord

Front 45

repair if intestines in umbilicus?

Back 45

surgery only if small omphalocele, otherwise staged surgery – stuffing all abdominal contents back in may inhibit breathing

Front 46

tear of abdominal wall near umbilicus

Back 46

gastroschisis – tissue becomes rigid and brittle – amniotic fluid bad for tissue

Front 47

hindgut events

Back 47

cloaca partitions, anal membrane breaks down

Front 48

cloaca partitions into what

Back 48

urogenital and anorectal canals

Front 49

mechanism for partitioning

Back 49

urorectal septum

Front 50

contributes to the bladder and urethra?

Back 50

urogenital sinus

Front 51

rectoanal canal contribute to?

Back 51

rectum and upper anus

Front 52

distal anal canal develops from?

Back 52

proctodeum

Front 53

separates the cloaca from the proctodeum?

Back 53

cloacal membrane

Front 54

divides cloacal membrane into urogenital and anal membranes?

Back 54

urorectal septum

Front 55

in order for urogenital and anal systems to be open to exterior, what must happen?

Back 55

urogenital and anal membranes must degenerate

Front 56

if anal membrane doesn’t break down – condition?

Back 56

congenital membranous atresia

Front 57

if urorectal septum fuses with posterior cloaca rather than cloacal membrane – result?

Back 57

complete anal atresia: VERY difficult to correct (no anal opening, no sphincters, etc.)

Front 58

if incomplete fusion of urorectal septum and cloacal membrane – result?

Back 58

because urorectal septum is bifid, incomplete fusion can mean fistulas connect urogenital and rectoanal organs

Front 59

tissue type: liver and gallbladder

Back 59

outgrowth of endoderm near distal foregut

Front 60

pancreas develops as

Back 60

dorsal pancreatic bud into dorsal mesentery, and ventral pancreatic bud into ventral mesentery

Front 61

ventral mesentery bud gives rise to

Back 61

half pancreas, gall bladder, liver

Front 62

with stretching of mesentery during growth process, what does ventral mesentery become?

Back 62

hepatic sinusoids and supportive connective tissue, liver capsule, lesser omentum, falciform, triangular and coronary ligaments of liver

Front 63

how do pancreatic buds come together?

Back 63

rotation of stomach and differential growth cause buds to join

Front 64

what does ventral pancreatic bud become?

Back 64

uncinate process

Front 65

embryonic tissue becomes: diaphragm central tendon?

Back 65

cranial part of septum transversum

Front 66

rest of diaphragm

Back 66

from dorsal mesentery assoc. w/ esophagus + projections of tissue: pleuroperitoneal folds from body wall

Front 67

how does congenital diaphragmatic hernia occur?

Back 67

pleuroperitoneal folds don’t complete separation of thoracic/abdominal cavity prior to return of midgut herniation back to abdominal cavity

Front 68

when might a congenital diaphragmatic hernia occur?

Back 68

10th week

Front 69

obstruction consequences

Back 69

distension proximally, reduced stool output

Front 70

indicator of upper obstructions

Back 70

projectile vomiting, at the time of feeding

Front 71

lower obstructions

Back 71

less forceful vomiting, delayed, with bile

Front 72

if mother is too large for dates – expect

Back 72

polyhydramnios – occlusion somewhere in GI tract

Front 73

Obstruction causes

Back 73

failure to recanalize, fetal vascular accident: if blood supply compromised, segment may fibrose, die

Front 74

obstruction cause in stomach

Back 74

congenital hypertrophic pyloric stenosis

Front 75

pancreatic cause of obstruction

Back 75

ring of pancreatic tissue that surrounds duodenum like a collar: annular pancreas

Front 76

if bowel becomes twisted

Back 76

congenital volvulus: can block both lumen and blood supply

Front 77

problem with congenital volvulus

Back 77

can become gangrenous – die

Front 78

congenital volvulus occurs usually with

Back 78

gut tubes that have, then lose mesentery asc/desc/duod

Front 79

condition where bowel telescopes on itself

Back 79

intussusception

Front 80

condition where anus is stenosed by incorrect chamber division

Back 80

imperforate anus

Front 81

intestine of newborn contains

Back 81

meconium: secretions, cells, detritis swallowed with amniotic fluid

Front 82

when are intestinal contents passed

Back 82

meconium passes in 1st 24 hrs

Front 83

why might intestinal contents not pass? suspect what?

Back 83

if too viscous (too much mucous) meconium won’t pass. common in kids with cystic fibrosus