GI embryo Flashcards

0
Q

what is in the foregut

A

Resp tree esophagus stomach proximal duodenum pancreas + ducts liver + gall bladder

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1
Q

what is in the midgut

A

distal duodenum jejunum ileum cecum ascending colon first half of transverse colon

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2
Q

what is in the hidngut

A

last part of transverse colon descending colon sigmoid colon proximal 2/3 rectum

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3
Q

what is dorsal mesentery made of? function? what does it give rise to?

A

• Dorsal mesentery connects gut tube with posterior abdominal wall • Mesentery carries blood vessels from the aorta to the gut tube • Continuous from cranial to caudal end gives rise to Greater omentum - 4 layered pocket hanging below stomach, superficial to ab organs

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4
Q

what is ventral mesentery made of? gives rise to?

A

ventral mesentery connects gut tube to the anterior body wall liver liver develops in ventral mesentery and grows into 2 parts: 1) anterior -Falciform ligament 2) posterior - Lesser Omentum with the Hepatoduodenal LIgament and Heptogastric Ligament ventral mesentery ONLY IN FOREGUT

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5
Q

Dorsal segmental arteries

A

supplies somites/muscle mass gives rise to posterior intercostals

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6
Q

Lateral segmental arteries

A

supply developing kidneys gives rise to renal arteries

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7
Q

Ventral segmental arteries

A

supply gut tube, through dorsal mesentery. initially paired, some drop out or fuse. 3 unpaired ventral arteries remain: celiac artery (foregut) SMA (midgut) IMA (hindgut)

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8
Q

describe the development of intestines

A

around 4-5 weeks the intestines are growing rapidly - gut tube grows faster than peritoneum so the intestines bulge out ventrally into umbilicar cord around weeks 8-9, there is enough room so intesttines come back in as intestines re-enter peritoneal cavity, they rotate 270 degrees counterclockwise around the Vitelline Duct/SMA. brings structures into their position - LI is anterior/framing the SI. cecum will but up near liver but will grow down. cecum elongates without growing wider - forms vermiform appendix

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9
Q

describe types of clinical issues due to Malrotation of Gut

A

1) Non rotation - 2) Reversed Rotation - Situs Inversus. OK if everything flips. 3) Subhepatic cecum - cecum does not grow down and remains at liver

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10
Q

Omphalocele

A

gut tube does not retrat, remains in the umbilical cord and covered in amnion

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11
Q

Gastroschisis

A

like omphalocele (gut tube does not retract out of the umbilical cord like it sholud) however, guts are NOT covered in amnion

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12
Q

Meckel’s Diverticulum?

A

vitelline duct normally closes/dissolves after guts retract. Vitelline duct remains and you get outpocketing of the SI

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13
Q

Fibrous Cord?

A

vitelline duct remains and forms a fibrous cord. guts anchored to anterior wall and cant move

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14
Q

Umbilicoileal Fistula

A

vitelline duct remains and forms a cord with a lumen - chyme can leak out!

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15
Q

Volvulus?

A

vitelline duct remains and twists

16
Q

subhepatic cecum?

A

type of issues due to malrotation of the intestines cecum does not grow down like it should, remains up near liver

17
Q

what is urorectal septum

A

in development the urogenital and digestive systems have a common outflow tract called Cloaca - we need to separate Urorectal Septum - tissue between allantois and hindut that grows down and forms the Anorectal canal and urogenital sinus

18
Q

how does liver form? what signals?

A

High BMP and FGF will tell endoderm to be liver BMP from septum transversum FGF from cardiogenic plate

19
Q

what signals forms pancreas? ventral and dorsal?

A

Low BMP and FGF - default tissue is ventral pancreas Dorsal pancreas develops on the other side of gut tube in presence of Shh

20
Q

what signals form exocrine vs. endocrine pancreas? cells within endocrine?

A

Exocrine pancreas - Notch sensitive Endocrine pancreas - Notch insensitive Pax 6 - Alpha (glucagon) and Gamma (PP) cells Pax 4 - beta (insulin) and delta (SS) cells - Develop LATER

21
Q

what is Annular Pancreas

A

Ventral pancreatic bud does not move properly - can surround/narrow the duodenum

22
Q

Coelom ? Development of

A

Intraembryonic coelom will give rise to thoracic and abdominal cavities Coelom = space lined by epithelium but derived from mesenchyme In the lateral plate mesoderm, a space develops between the somatic and splanchinc mesoderm layers. EEC = Extraembryonic Coelom = Chorion Cavity Over time IEC and EEC fuse - only in areas where there are somites. Lateral folding will form defined IEC and close it Cephalocaudal folding will get rid of EEC.

23
Q

what are the 4 parts of the diaphram?

A
  1. septum transversum 2. Pleuroperitoneal membrane (used to be capsules of mesonphric kidneys) 3. mesentery of esophagus 4. posterior body wall SPEP
24
Q

how does diaphragm develop? (thorax and abomden separation - peritoneal cavity)

A

as septum transversusm moves down, it hits different strucutres. stops at posterior body wall. Diphragm forms from things septum transversum hits

25
Q

how does pleural cavity and pericardial sac develop/separate?

A

intussuseption of common cardinal veins - forms a Pleuropericardial membrane