Lecture 4: digestive system

Question 1

the endodermal gut tube is formed

Answer 1

by body folding

Question 2

epithelial tube is surrounded by..

Answer 2

splanchnic mesoderm

Question 3

endoderm gives rise to the

Answer 3

epithelial cells of the gut tube (pharyngeal foregut, digestive system and respiratory system)

epithelial linning and glands of the digestive system

Question 4

splanchnic mesoderm gives rise to

Answer 4

smooth muscle, connective tissue, blood vessels, visceral mesothelium

Question 5

vitelline duct

Answer 5

communication between the midgut and the yolk sac

-this connection becomes the core of the umbilical cord

Question 6

primordial gut is closed at

Answer 6

the ends of the oropharyngeal membrane and the cloacal membrane

Question 7

bilayer dorsal mesentery

Answer 7

suspends the abdominal viscera in the body cavity

Question 8

ventral mesentery

Answer 8

connects the stomach and liver to the ventral body wall

Question 9

regions of the pharyngeal foregut

Answer 9

buccopharyngeal membrane to respiratory diverticulum

Question 10

regions of the proper foregut

Answer 10

caudal to pharyngeal tube to superior duodenum (superior to ampulla of pancreatic duct)

Question 11

regions of the midgut

Answer 11

inferior to bile duct/pancreatic duct to the junction of the right two-thirds and left third of the transverse colon

Question 12

regions of the hindgut

Answer 12

left third of transverse colon to the cloacal membrane

Question 13

derivatives of the foregut

Answer 13

• lower respiratory tract
• esophagus to duodenum (proximal to bile duct only)
• liver and biliary apparatys (hepatic ducts, gallbladder and bile duct), pancreas
• the artery of the foregut is the celiac trunk

Question 14

derivatives of the midgut

Answer 14

• inferior duodenum to the right 2/3 of transverse colon

- the artery of the midgut is the superior mesenteric artery

Question 15

derivatives of the hindgut

Answer 15

• left 1/3 of transverse colon to the rectum upper anal canal
• endoderm of the handgun also forms the epithelial lining of the bladder and urethra
• the artery of the hindgut is the inferior mesenteric artery

Question 16

where does the esophagus develop

Answer 16

at the ventral wall of the foregut below the pharynx

Question 17

esophageal muscle fiber of the upper 1/3

Answer 17

striated (muscular externa)
derived from myotomes
innervated by vagus nerve (CN X)

Question 18

esophageal muscle fiber of the lower 2/3

Answer 18

smooth
derived from splanchnic mesenchyme
innervated by vagus nerve (CN X)

Question 19

esophagotracheal septum

Answer 19

partitions the trachea from the esophagus

Question 20

foregut development

Answer 20

• stomach rotates 90 degrees clockwise around the longitudinal axis
• rotation causes the duodenum to bend into a C shape and to the right

Question 21

—- and —- become retroperitoneal

Answer 21

pancreas and duodenum

Question 22

upper duodenum is —- and lower is —-

Answer 22

foregut and midgut

Question 23

duodenum is supplied by

Answer 23

both the celiac artery and the superior mesenteric artery

Question 24

hepatic diverticulum (liver bud) formation

Answer 24

endodermal thickening appears over ventral duodenum

Question 25

septum transversum

Answer 25

location where the hepatic diverticulum grows

Question 26

support stroma develop

Answer 26

from septum transversum and splanchnic mesoderm

Question 27

hepatocytes and biliary apparatus derive from

Answer 27

endoderm

Question 28

hepatic diverticulum divides into

Answer 28

- large cranial portion that will give rise to the primordial of the liver - small ventral outgrowth of the bile duct that gives rise to the gallbladder and the cystic duct

Question 29

hepatic diverticulum and the gut tube stay connected via

Answer 29

duct that will later become the bile duct

Question 30

pancreas development

Answer 30

- initially a ventral and dorsal bud originating from endoderm of duodenum - rotation of the gut tube moves ventral bud dorsally and both fuse

Question 31

primitive umbilical ring

Answer 31

junction of embryonic ectoderm and the amnion

Question 32

at week 5 which structures pass through the primitive umbilical ring

Answer 32

- connecting stalk with umbilical vessels - yolk stalk (connects midgut to yolk sac) - canal connecting intra and extra embryonic cavities - wharton's jelly (protects blood vessels) - yolk sac is in the chorionic cavity

Question 33

physiological herniation

Answer 33

intestinal loop enter the extra embryonic cavity during 6th week of development

Question 34

physiological herniation is due to

Answer 34

- continued midgut elongation (growth of the small intestine is more rapid and greater than growth of the abdomen) - rapid growth and expansion of the liver (abdominal cavity is too small for the organs)

Question 35

development of the hindgut

Answer 35

-dorsal mesentery shortens and the descending colon becomes retroperitoneal