9. Digestive System and Peritoneal Membranes Flashcards
The epithelium of the GI tract is from endoderm. What comes from mesoderm, Neural crest, and ectoderm?
Meso: smooth muscle and CT
NCC: autonomic ganglion
Ectoderm: mouth and anal canal
The endoderm is divided into three sections, the foregut, midgut and hingut. What divides them into sections?
the yoke sac
What is made from foregut? (5)
esophagus, stomach, liver, pancreas, biliary apparatus, and proximal dudoenum
What is made from midgut? (4)
SI, cecum, veriform appendix, ascending colon and right half of transverse colon
What is made from hindgut? (5)
left half of transverse colon, descending colon, sigmoid colon, rectum, superior anal canal
What are the main vessesl for foregut, midgut and hindgut?
celiac
superior mesenteric artery
inferior mesenteric artery
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?
smooth from the splanchnic layer of lateral plate
skeletal from mesoderm of the pharyngeal arch 4/6
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
Prenatally: polyhydramnios
Birth: coughing, gagging, blue, vomiting, drooling
During the fourth week the stomach grows, faster on the dorsal surface. How does it rotate and what are the degrees?
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
Hypertrophic pyloric stenosis is very common, is when circular and some longitudinal muscles of the pylorus hypertrophy. What is the presentation? (3)
post feeding PROJECTILE vomiting that is nonbilious
Small stool
No weight gain/weight loss
What vertebral level/ plane is the pylorus of the stomach at?
L1 - transpyloric plane
The liver and gallbladder both come from the hepatic diverticulum. Below the stomach is where the heptic diverticulum occurs and contains what two things?
liver bud which (grows towards septum transversum)
gall bladder
Along with the liver and gallbaldder, what other ducts and bud are formed from the hepatic diverticulum?
Hepatic duct
Bile duct
ventral pancreatic bud
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?
mesoderm
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?
dorsal pancreatic bud/primordia… will become body and tail
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?
Duct in body/tail from dorsal primordia
main Duct into duodenum is from ventral primordia
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?
there is a bifed ventral pancreatic bud, it wraps around the duodenum obstructing it.
Spleen is from mesoderm during week 5, what does it help with?
hematopoeisis during weeks 9-28
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?
superior mesenteric A is the axis around which the stomach rotates
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?
180 degrees, the proximal (SI) part moves under the distal part (LI) to get to its mature spot (270 degress total)
What is omphalocele which occurs during week 10?
failure of bowel to return to the body cavity, bowel will be covered in amnion and peritoneum (only 90 degrees rotation occurs)
What is gastroschisis which occurs during week 4?
anterior abdominal wall doesnt close, bowel exposed without peitoneum (occurs in nebraska)
Hirschsprungs disease or megacolon occurs due to?
NCC fail to migrate to stomach, lack ganglion cells distal to dilated segment (no parasympathetics)
What is a congential umiblical hernia?
intestines ‘pop’ out through a weak umbilicus
What is the problem with each of the following abnormalities? Nonrotation of the midgut and reversed rotation (SI in front of LI)?
Nonrotation causes blockage/tightness at the hepttic (splenic) plexures
Reversed: duodenum crosses over LI, obstruction here
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?
Duplication: where this is a pocket that food can go into
Stenosis: apoptosis doesnt occur leaving endodermal proliferation in tube.
Meckel’s diverticulum occurs when there is persistent vitelline duct attached to umbilicus and the ileum. What does this lead to? (3)
omphalomesenteric fistula: poop thru belly
omphalomesenteric cyst/ligament: no symptoms, ok to live
What are the rules of 2 for meckel’s diverticulum? (6)
2 years of age 2x more prevelant in males 2 tissue types: pancreatic/gastric 2feet from ileocecal junction 2% population 2 inches long
The urorectal setptum (mesoderm) grows towards the cloacal membrane and divides it, forming?
urogenital membrane (bladder) anal membrane (anus) *both endo/ectoderm and the perineal body formed
The upper 2/3 above the pectinate line of the anal canal is from endoderm. What is the blood/nerve/ln?
B: Inferior mesenteric
N: Autonomics
LN: Inferior mesenteric
The lower 1/3 below the pectinate line of the anal canal is from ectoderm. What is the blood/nerve/LN?
B: middle and inferior rectal
N: pudendal
LN: Superior inguinal
What happens if the septum migrate and separates the cloaca, but the endoderm and ectoderm layers do not meet at the right place?
anorectal malfromations
To form the peritoneal cavity, what must occur?
septum transversum fuses with the pleuroperitoneal membrane (somatic layer of the lateral plate), forming the diaphragm
To close the pericardioperitoneal canal, what occurs?
after the septum transversum and pleuroperitoneal membrane fuse, tissue body from the wall is pulled into the diaphragm to closee the pericardiperitoneal canal
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?
right and left crus of the diaphragm
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?
congenital diaphragmatic hernia
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?
dorsal is attached to the posterior wall and ventral (which degenerate except for forgut) attach to the anterior wall
What do the dorsal (3) and ventral mesogastrium give rise to?
greater omentum, gastrosplenic ligament, splenorenal lig lesser omentum (somtach to liver)
What does the ventral mesentery of abdominal cavity give rise to?
falciform ligament (ant body to liver)
What does the mesoduodenum and mesentery proper give rise to?
mesentery around duodenum (1st part-maybe)
mesentery containing jejunum and ileum
What does the mesocolon and mesorectum give rise to?
mesentery around transverse and sigmoid colon
mesentery around the rectum
as the stomach rotates, pulls the dorsal mesogastrium and folds on itself, making a 4 layer greater omentum and omental bursa, which is?
the space between the stomach and the posterior body wall
What are the intraperitoneal organs? (6) comepletely covered in visceral peritoneum
stomach tail pancreas 1st part duodenum Jejunum,ileum transverse colon sigmoid colon
