Digestive Development Flashcards
(23 cards)
The foregut becomes (6)
pharynx, esophagus, stomach, cranial duodenum, liver and pancreas
The midgut becomes (4)
remaining SI, cecum, ascending colon, part of the transverse colon, The longest segment
The hindgut becomes … (3)
transverse and descending colon and cloaca
The cloaca divides into…
rectum and most of the anal canal
Twisting happens because of…
a lot of differential growth in proximal and distal portions of the midgut (more growth in proximal) not enough room in the early embryo
Physiological umbilical hernia is…
when intestines herniate within the umbilical cord (intestines are always covered by a sheet to protect from amniotic cavity) develop for about a month outside the body
6 steps in gut tube position and arrangement
- stomach bends and rotates 2. duodenum goes to the right 3. midgut herniates 4. midgut returns to abdominal cavity (turns 270 degrees) (at about 10 weeks in humans) 5. mesenteries move a bit and are modified because of it 6. cloaca is divided by urogenital septum
Dorsal and ventral mesenteries happen….(2 places)
cranial to duodenum (stomach - greater and lesser om. - and esophagus) and caudal at the cloaca
Omalocoele is…
defect where intestines remain outside the abdomen defect in physiological umbilical hernia
Gastroschisis is…
intestines and abdominal contents freely protrude the wall
Difference between Omalocoele and gastroschisis
Omalo is within the umbilical cord and gastroschisis is not protected by umbilical cord
Recanalisation steps (3)
intestines occlude from proliferation of endodermal cells Very soon after, apoptosis occurs in those cells and a canal is made
Defects in recanalisation (intestinal atresia) (3)
- mucosal (web) -most common and most simple 2. Fibrous cord (solid core) 3. Mesenteric gap (complete segmental absence) There are other more complex ones like ‘apple-peel’ but meh…
Overo Lethal White
Autosomal genetic disorder (mating two carrier paints will give 25% chance of OLW)
Genetics around OLW
affects homozygotes for ILE8LYS mutation on enddothelin receptor type B
Selecting for whites does what…? (It’s a long one buddy - 6)
selecting for white is selecting against black black involves melanocytes No melanocytes means no neural crest cells(Neural crest cells are important in the development of melanocytes) No neural crest cells means no neural ganglia no neural ganglia means no intestinal motility or peristalsis Hence, COLIC
Urorectal septum does…
seperates the intestinal and urinary systems in the common cloaca
After urorectal septum is in place,
the cloacal membrane becomes the anal and urogenital membranes
between the anal and urogenital membranes is…
the perineum
When the anal membrane does not break down, you get…
anal atresia or atresia ani
When there is incomplete growth of the urogenital septum, …
there is communication between the rectum and bladder (lack of complete closure) Callled Urorectal Fistula
Urorectal fistula is…
lack of complete closure between the rectum and bladder
two other fistulas we talked about are
rectovaginal and urethrorectal fistulas
