GI development

Question 1

at what point is organogenesis complete?

Answer 1

12 weeks

Question 2

which organs are formed at what points of development?

Answer 2

• 4 weeks – gut tube forms
• 5 weeks – liver and pancreas formation
• 6 weeks – ventral pancreatic bud fuses with dorsal bud
• 7 weeks – primary intestinal loop herniates into the umbilicus and rotates
• 11 weeks – midgut rotates and retracts into abdomen
• 12 weeks – ascending and descending colon attach to body wall

Question 3

what supplies the foregut, midgut and hindgut?

Answer 3

• Foregut supplied by the coeliac artery
• Midgut supplied by the superior mesenteric artery
• Hindgut supplied by the inferior mesenteric artery

Question 4

what does the foregut give rise to?

Answer 4

pharynx, oesophagus, stomach, cranial half of the duodenum and the ampulla of Vater, liver parenchyma and hepatic duct epithelium, gallbladder, cystic duct and common bile duct

Question 5

what does the midgut give rise to?

Answer 5

caudal half of duodenum, jejenum, ileum, cecum, appendix, ascending colon and proximal 2/3 of transverse colon

Question 6

what does the hindgut give rise to?

Answer 6

distal 1/3 of transverse colon, descending colon, rectum and urogenital sinus

Question 7

name foregut development abnormalities?

Answer 7

• Oesophageal atresia/stenosis – blockage
• Tracheo-oesophageal fistulae
• Congenital hiatus hernia
• Pyloric stenosis
• Duodenal atresia

Question 8

what does failure to separate the oesophagus and respiratory tract lead to?

Answer 8

• Failure of separation
• Atresia of the oesophagus
• Atresia of the oesophagus with fistula

Question 9

what can cause reflux in infants?

Answer 9

overfeeding

GORD

Question 10

what can cause GORD in babies?

Answer 10

o Immaturity of motor function in neonates
o Suck reflex not present prior to 32 weeks’ gestation
o Lower oesophageal sphincter pressure is reduced
o Gastric emptying delayed
o Slow mouth to anus transit time

Question 11

why does GOR in a child improve?

Answer 11

LOS develops

Question 12

what is duodenal atresia?

Answer 12

blockage in the duodenum

Question 13

how does duodenal atresia present?

Answer 13

vomiting (maybe an hour or 2 after feeding)

Question 14

how does an x-ray of duodenal atresia present?

Answer 14

classic double bubble

Question 15

how does a diaphragmatic hernia present?

Answer 15

• Presents w severe respiratory distress bc of pulmonary hypoplasia

Question 16

where does a diaphragmatic hernia occur?

Answer 16

posterolateral aspect of the diaphragm

Question 17

what causes alongation and rotation of the midgut?

Answer 17

rapid growth

Question 18

name midgut developmental abnormalities?

Answer 18

• Jejunal atresia
• Malrotation
• Meckel’s diverticulum
• Omphalocele – gut is outside the baby’s body
• Gastrochisis

Question 19

how does jejenal atresia present?

Answer 19

presents as vomiting with BILE (not seen in other atresias – bile only present in jejenum)

Question 20

how can jejunoileal atresia be classified?

Answer 20

• I, II, IIIa, IIIb (apple peel), IV

Question 21

what happens in malrotation, what does it cause and how is it treated?

Answer 21

• Bowel twisted around the superior mesenteric artery  necrotic, gangrenous gut
• Treated by unwinding the bowel and seeing if the blood supply returns

Question 22

what is the duodenum-jejenum junction anchored by?

Answer 22

ligament of Treitz

Question 23

what causes intestinal malrotation?

Answer 23

failure of normal rotation and fixation

• Duodenojejunal junction is to the right of the spine
• Ligament of Treitz is absent
• Abnormal placement of mesenteric ligaments may obstruct the second portion of the duodenum

Question 24

what does persistence of the vitelline duct give rise to?

Answer 24

Meckel’s diverticulum

Question 25

how does Meckel's diverticulum occur?

Answer 25

- vitelline duct loses connection to the midgut loop before it goes to the abdominal cavity - perisstence of proximal part forms MD - MD attached to terminal ileum - ectopic gastric mucos or pancreatic tissue may be present in MD

Question 26

what hindgut abnormalities can occur?

Answer 26

anorectal abnormalities

Question 27

what gives rise to the rectum and urogenital sinus?

Answer 27

cloaca

Question 28

what do neural crest cells give rise to?

Answer 28

enteric ganglia

Question 29

what does Hirschprung’s disease result from?

Answer 29

failure of development of the enteric ganglia (no ganglion cells)

Question 30

how does Hirschsprung's disease occur?

Answer 30

failure of neural crest cells to migrate to the correct location leads to absence of ganglion cells

Question 31

how does Hirschsprung's disease present?

Answer 31

neonatal colonic obstruction

Question 32

how does human small intestinal villus and crypt formation occur?

Answer 32

through a process of epithelial and mesenchymal reorganisation

Question 33

what is the surface area of the small intestine increased by?

Answer 33

* Folding of the mucosa into plicae circulares * Formation of villi * Development of microvilli

Question 34

when is intestinal elongation rapid?

Answer 34

in utero

Question 35

when do most small intestinal microvillus enzymes begin to appear?

Answer 35

8 weeks

Question 36

when does • Small intestinal lactase activity reach maximal levels?

Answer 36

end of gestation

Question 37

when are fetuses unable to swallow/breathe?

Answer 37

before 32-34 weeks of gestation

Question 38

when do teeth appear?

Answer 38

6 months of age

Question 39

how is breast's milk different to cow's milk?

Answer 39

• Lower protein in breast milk o More Whey protein > Casein – whey more easily digested • Lower minerals eg Na – lower solute load on the baby • Essential fatty acids – better absorbed • Lipase - digestion • Anti-infective - • Vitamin A/C/D greater • Lower calcium and phosphorus (high phosphorus in CM leads to hypocalcemic tetany)

Question 40

when can you stop using infant formula?

Answer 40

12 months

Question 41

when should weaning be introduced?

Answer 41

6 months

Question 42

when should allergenic food be introduced?

Answer 42

6 months

Question 43

what foods can be considered allergenic?

Answer 43

eggs | gluten containing food

Question 44

how should eggs be introduced?

Answer 44

egg yolk first, then egg whites