Development of Digestive System (Exam 3) Flashcards
The primitive gut is closed at both ends by ________ membranes.
bilaminar
What are the 2 bilaminar membranes of the primitive gut?
- oropharyngeal membrane
- cloacal membrane
The primitive gut is suspended to body wall by ___________.
dorsal mesentery
What provides blood supply to the primitive gut?
ventral branches of aorta
Digestive system is the main organ system derived from embryonic __________.
endoderm
What are the 4 divisions of the primitive gut?
- pharynx
- foregut
- midgut
- hindgut
Which division of the primitive gut is the largest and forms 2/3 of the descending colon?
midgut
Which 4 tissues/organs are derived from the foregut?
esophagus
stomach
liver
pancreas
_______ of the walls of the foregut results in changes in position and appearance which derives the stomach.
differential growth
The _______ of the stomach is derived from the dorsal dilation of foregut, while ________ is from the ventral dilation.
greater curvature
lesser curvature
What is the order of differentiation of the ruminant stomach compartments?
- rumen
- reticulum
- omasum
- abomasum
Match the ruminant stomach compartment to how it is derived:
- as caudoventral pocket of fundus
- as expansion of fundus
- as dilation of pyloric region
- as expansion of lesser curvature
- reticulum
- rumen
- abomasum
- omasum
When do the compartments of the ruminant stomach reach adult size?
after 1 year of age
What is the largest gland in the body?
liver
Which 3 species do not have a gallbladder?
horse
rat
whale
The liver begins as a hepatic diverticulum or (dorsal/ventral) outgrowth of the foregut.
ventral
Liver sinusoids are formed by proliferation of endodermal cells into _____ that anastomose around which 2 veins?
cord
vitelline + umbilical Vv
The expansion of the developing liver narrows the connections with the foregut and the hepatic ducts merge to form ______________.
common hepatic duct
The cystic duct joins the hepatic duct to form ________.
bile duct
Where does the bile duct open?
at the site of origin of the liver bud
The liver expands temporarily into what structure that is later the tendinous center of the diaphragm?
septum transversum
The ventral mesentery is divided by the liver into what 2 structures?
- lesser omentum
- falciform ligament
What are the 2 parts of the lesser omentum?
- hepatogastric ligament
- hepatoduodenal ligament
The origin of hepatic diverticulum is shifted dorsally by differential growth of ________.
duodenum
What digestive organ has dual origin?
pancreas
The dual origin of the pancreas is made up of the ____ and ____ diverticulum.
dorsal + ventral
The dorsal diverticulum forms the (right/left) lobe of the pancreas with the _______ duct.
left
accessory
The ventral diverticulum forms the (right/left) lobe of the pancreas with the ________ duct.
right
pancreatic
Match each species to which pancreatic ducts they have present:
- dog/horse
- cat/small ruminant
- pig/ox
- pancreatic + accessory
- only pancreatic
- only accessory
During midgut development, the loop rotates around the axis of ________ A.
cranial mesenteric
What determines the direction of rotation of the midgut?
connection to yolk sac and uneven growth
The sequence of the withdrawal of loop of midgut determines what?
final placement of intestines
Cranial limb of midgut passes to the (right/left) (caudal/in front of) cranial mesenteric A.
left
caudal
Caudal limb of midgut passes to (right/left) (caudal/in front of) cranial mesenteric A.
right
in front of
The cranial limb of the midgut forms what 2 structures?
duodenum
jejunum
Complete rotation of the midgut involves ____ degrees (clockwise/counterclockwise) around the cranial mesenteric A.
270
counterclockwise
Complete rotation of the midgut forms what structure?
root of mesentery
Formation of a secondary loop of the ascending colon forms a ______ in pigs and ruminants, and a ____ in horses.
spiral colon
bend colon
What 3 structures are derivates of the hindgut?
- part of descending colon
- rectum
- anal canal
Term for common chamber for digestive and urogenital systems
cloaca
The cloaca persists in what 3 adult species?
birds
reptiles
amphibians
The cloaca is divided by a urorectal septum into what 2 structures?
- anal canal
- urogenital sinus
Term for caudal diverticulum of hindgut that forms splanchnic mesoderm + yolk sac forming urinary bladder and urachus.
allantois
Term for first stool of green material from bile salts and swallowed amniotic fluid.
meconium
Term for temporary occlusion of gut by epithelial proliferation.
gut atresia
(T/F) Gut atresia anomalies occur simultaneously.
False - related anomalies can occur at any level
When should meconium be completely eliminated by?
4th day after birth
What is a common cause of colic in equine neonates?
meconium retention
What are the two most common gut defects?
- atresia
- stenosis
3 possible causes of gut atresia and stenosis
- fetal vascular “accidents”
- lack of re-canalization
- gut rotation defects
(T/F) In some species, gut defects such as atresia and stenosis, are genetic conditions.
True
Term for imperforated anus due to persistent anal membrane.
anal atresia
Term for sign of anal atresia where animal tries but cannot defecate.
tenesmus
How do you treat/manage anal atresia?
surgery
Term for ectopic anal opening due to error in separation of cloaca.
fistula
Neuromuscular gut disorder where there is a lack of relaxation of esophageal sphincter relaxation which leads to regurgitation of undigested food.
congenital megaesophagus
How is congenital megaesophagus managed? (2 ways)
bailey chair feeding
PEG tube
Congenital megaesophagus is the most common cause of _______ in cats and dogs.
regurgitation
Congenital megacolon is the lack of _____ function due to the absence of _____ ganglia.
motor
myenteric
3 symptoms of congenital megacolon
- tenesmus
- constipation
- abdominal distension
“Mega” conditions like megacolon involve a lack of migration of what embryonic cells?
neural crest cells
Term for incomplete closure of abdominal wall at umbilicus.
congenital umbilical hernia
Which species has the highest incidence of congenital umbilical hernia?
pigs
Term for when part of the body wall is open and not covered by peritoneum.
omphalocele