9. Digestive System and Peritoneal Membranes

Question 1

The epithelium of the GI tract is from endoderm. What comes from mesoderm, Neural crest, and ectoderm?

Answer 1

Meso: smooth muscle and CT
NCC: autonomic ganglion
Ectoderm: mouth and anal canal

Question 2

The endoderm is divided into three sections, the foregut, midgut and hingut. What divides them into sections?

Answer 2

the yoke sac

Question 3

What is made from foregut? (5)

Answer 3

esophagus, stomach, liver, pancreas, biliary apparatus, and proximal dudoenum

Question 4

What is made from midgut? (4)

Answer 4

SI, cecum, veriform appendix, ascending colon and right half of transverse colon

Question 5

What is made from hindgut? (5)

Answer 5

left half of transverse colon, descending colon, sigmoid colon, rectum, superior anal canal

Question 6

What are the main vessesl for foregut, midgut and hindgut?

Answer 6

celiac
superior mesenteric artery
inferior mesenteric artery

Question 7

Tracheoesophageal fistula is an abnormal passage between tracheal and esophagus that is usually associated with a blind end esophagus. Occurs in week 5 due to failure of septums to fuse. Where does the smooth and skeletal muscle of the esophagus come from?

Answer 7

smooth from the splanchnic layer of lateral plate

skeletal from mesoderm of the pharyngeal arch 4/6

Question 8

What is the best cause for TE fistula prenatally and what can be seen at birth?(6) Remember this can be diagnosed by seeing coiling of a NG tube

Answer 8

Prenatally: polyhydramnios
Birth: coughing, gagging, blue, vomiting, drooling

Question 9

During the fourth week the stomach grows, faster on the dorsal surface. How does it rotate and what are the degrees?

Answer 9

rotates longitudinally first 90 degrees (ventral to right, dorsal to left) and then rotates anteroposterior 90 degrees. leaving you with left side ventral and right side dorsal

Question 10

Hypertrophic pyloric stenosis is very common, is when circular and some longitudinal muscles of the pylorus hypertrophy. What is the presentation? (3)

Answer 10

post feeding PROJECTILE vomiting that is nonbilious
Small stool
No weight gain/weight loss

Question 11

What vertebral level/ plane is the pylorus of the stomach at?

Answer 11

L1 - transpyloric plane

Question 12

The liver and gallbladder both come from the hepatic diverticulum. Below the stomach is where the heptic diverticulum occurs and contains what two things?

Answer 12

liver bud which (grows towards septum transversum)

gall bladder

Question 13

Along with the liver and gallbaldder, what other ducts and bud are formed from the hepatic diverticulum?

Answer 13

Hepatic duct
Bile duct
ventral pancreatic bud

Question 14

Bile is produced in the 12th week, and hematopoesis (cells from mesoderm) occurs week 6-30 in liver to make blood. Stroma cells are from?

Answer 14

mesoderm

Question 15

The ventral pancreatic bud/primordia is the head and uncinate process. What is on the other side of the ventral and what will it become?

Answer 15

dorsal pancreatic bud/primordia… will become body and tail

Question 16

As the duodenum rotates to the right, the ventral bud rotates around and fuses with the dorsal bud. Where did the pancreatic duct come from?

Answer 16

Duct in body/tail from dorsal primordia

main Duct into duodenum is from ventral primordia

Question 17

What is annular pancreas which presents with similar symptoms as pyloric stenosis except with bilious vomit if it is below the bile duct, without if it is above bile duct?

Answer 17

there is a bifed ventral pancreatic bud, it wraps around the duodenum obstructing it.

Question 18

Spleen is from mesoderm during week 5, what does it help with?

Answer 18

hematopoeisis during weeks 9-28

Question 19

The midgut rotates 90 degress out into the vitelline duct (to umbilicus week 6) due to large liver and kidneys. What is the artery that is used as an axis for rotation?

Answer 19

superior mesenteric A is the axis around which the stomach rotates

Question 20

A distal/caudal bulge occurs where the cecum is and the proximal SI becomes convoluted. What is the final rotation back in during week 10?

Answer 20

180 degrees, the proximal (SI) part moves under the distal part (LI) to get to its mature spot (270 degress total)

Question 21

What is omphalocele which occurs during week 10?

Answer 21

failure of bowel to return to the body cavity, bowel will be covered in amnion and peritoneum (only 90 degrees rotation occurs)

Question 22

What is gastroschisis which occurs during week 4?

Answer 22

anterior abdominal wall doesnt close, bowel exposed without peitoneum (occurs in nebraska)

Question 23

Hirschsprungs disease or megacolon occurs due to?

Answer 23

NCC fail to migrate to stomach, lack ganglion cells distal to dilated segment (no parasympathetics)

Question 24

What is a congential umiblical hernia?

Answer 24

intestines ‘pop’ out through a weak umbilicus

Question 25

What is the problem with each of the following abnormalities? Nonrotation of the midgut and reversed rotation (SI in front of LI)?

Answer 25

Nonrotation causes blockage/tightness at the hepttic (splenic) plexures
Reversed: duodenum crosses over LI, obstruction here

Question 26

The formation of the gut lumen has 4 steps: hollow tube, endodermal proliferation, apoptosis/recanalization, gut tube. What are the two abnormalities associated with this?

Answer 26

Duplication: where this is a pocket that food can go into
Stenosis: apoptosis doesnt occur leaving endodermal proliferation in tube.

Question 27

Meckel’s diverticulum occurs when there is persistent vitelline duct attached to umbilicus and the ileum. What does this lead to? (3)

Answer 27

omphalomesenteric fistula: poop thru belly

omphalomesenteric cyst/ligament: no symptoms, ok to live

Question 28

What are the rules of 2 for meckel’s diverticulum? (6)

Answer 28

2 years of age
2x more prevelant in males
2 tissue types: pancreatic/gastric
2feet from ileocecal junction
2% population
2 inches long

Question 29

The urorectal setptum (mesoderm) grows towards the cloacal membrane and divides it, forming?

Answer 29

urogenital membrane (bladder)
anal membrane (anus)
*both endo/ectoderm
and the perineal body formed

Question 30

The upper 2/3 above the pectinate line of the anal canal is from endoderm. What is the blood/nerve/ln?

Answer 30

B: Inferior mesenteric
N: Autonomics
LN: Inferior mesenteric

Question 31

The lower 1/3 below the pectinate line of the anal canal is from ectoderm. What is the blood/nerve/LN?

Answer 31

B: middle and inferior rectal
N: pudendal
LN: Superior inguinal

Question 32

What happens if the septum migrate and separates the cloaca, but the endoderm and ectoderm layers do not meet at the right place?

Answer 32

anorectal malfromations

Question 33

To form the peritoneal cavity, what must occur?

Answer 33

septum transversum fuses with the pleuroperitoneal membrane (somatic layer of the lateral plate), forming the diaphragm

Question 34

To close the pericardioperitoneal canal, what occurs?

Answer 34

after the septum transversum and pleuroperitoneal membrane fuse, tissue body from the wall is pulled into the diaphragm to closee the pericardiperitoneal canal

Question 35

The septum transversum makes the central tendon of the diaphragm. The body wall makes the peripheral muscles and the dorsal mesentery of the esophagus makes what?

Answer 35

right and left crus of the diaphragm

Question 36

What occurs due to failure of fusion between septum transversum and pleuroperitoneal membranes… occuring on the left side and causing herniation of abdominal contents, hypoplatic lungs and polyhydramnios?

Answer 36

congenital diaphragmatic hernia

Question 37

A mesentery is a double layer of serous (splanchnic) membrane to allow BV and N to reach organs. What is the difference between dorsal and ventral mesentery?

Answer 37

dorsal is attached to the posterior wall and ventral (which degenerate except for forgut) attach to the anterior wall

Question 38

What do the dorsal (3) and ventral mesogastrium give rise to?

Answer 38

greater omentum, gastrosplenic ligament, splenorenal lig
lesser omentum (somtach to liver)

Question 39

What does the ventral mesentery of abdominal cavity give rise to?

Answer 39

falciform ligament (ant body to liver)

Question 40

What does the mesoduodenum and mesentery proper give rise to?

Answer 40

mesentery around duodenum (1st part-maybe)

mesentery containing jejunum and ileum

Question 41

What does the mesocolon and mesorectum give rise to?

Answer 41

mesentery around transverse and sigmoid colon

mesentery around the rectum

Question 42

as the stomach rotates, pulls the dorsal mesogastrium and folds on itself, making a 4 layer greater omentum and omental bursa, which is?

Answer 42

the space between the stomach and the posterior body wall

Question 43

What are the intraperitoneal organs? (6) comepletely covered in visceral peritoneum

Answer 43

stomach
tail pancreas
1st part duodenum
Jejunum,ileum
transverse colon
sigmoid colon