s2. development of the gut 1 and 2

Question 1

what are the 3 sections of the mesoderm

Answer 1

lateral plate
intermediate
paraxial (next to notochord)

Question 2

what’s the two divisions of the lateral plate of mesoderm?

Answer 2

SOMATIC (body walls)

SPLANCHNIC (viscera)

Question 3

ectoderm gives rise to

Answer 3

epidermis

nerve tissue

Question 4

endoderm gives rise to

Answer 4

epithelial lining of GI tract

Question 5

intermediate plate of mesoderm gives rise to

Answer 5

kidneys and gonads

Question 6

paraxial plate of mesoderm gives rise to

Answer 6

somites> skeletal muscle, vertebra, cartilage

Question 7

two types of folding that occur in early embryo

Answer 7

saggital

cranio-caudal

transverse

Question 8

what embryonic structures are present after saggital folding

Answer 8

amniotic cavity
trilaminar disc
yolk sac
head and tail end

Question 9

what is the vitelline duct? pathology?

Answer 9

connection between midgut and yolk sac

usually obliterates by birth.
if not: Merckel’s Diverticulum= out pouch of small intestine > faecal material leaking from umbilicus

Question 10

cranio caudal folding results in

Answer 10

foregut (oesophagus>duodenum-midpoint of 2nd part)
midgut (duodenum> distal 2/3 transverse colon)
hindgut (distal 1/3 transverse colon> upper anal canal)

mouth
heart
anus

FORMS HEAD AND TAIL END

Question 11

splanchnopleuric mesoderm forms

Answer 11

viscera

Question 12

somatopleuric mesoderm forms

Answer 12

body walls and dermis

Question 13

intraembryonic coelom gives rise to

Answer 13

thoracic and abdominal cavities

Question 14

what forms the gut tube

Answer 14

yolk sac

Question 15

when does the bucopharyngeal membrane rupture?

Answer 15

4th week to give mouth open to amniotic cavity

Question 16

when does cloacal membrane rupture?

Answer 16

7th week (anus)

Question 17

describe embryonic blood supply to the gut

Answer 17

foregut- coeliac artery
midgut- superior mesenteric artery
hindgut- inferior mesenteric artery

Question 18

what happens to the foregut in the 5th week and pathology?

Answer 18

endoderm proliferates
occludes lumen temporarily
rencanalise (9th week)

• failed proliferation of endoderm > end up with closed sections of gut
• failed recanalisation 1/3000 births

Question 19

differences in pain in relation to somatic and splanchnic mesoderm

Answer 19

parietal peritoneum>somatic- can localise pain (good sensory supply)
visceral peritoneum>splanchnic- vague pain

Question 20

what is Epiploic foramen (also called the foramen of Winslow) ?

Answer 20

passage between the greater sac and the lesser sac. >allowing communication between these two spaces.

Question 21

how are the peritoneal sacs formed?

Answer 21

from foregut rotation
greater sac= bulk of peritoneal cavity
lesser sac= behind stomach

Question 22

list the peritoneal ligaments from anterior to posterior

Answer 22

falciform ligament
(liver)
lesser momentum
(stomach)
gastrosplenic ligament
(spleen)
spleno-renal ligament 
(L kidney)

these are all double folds of peritoneum

Question 23

how does the pancreas form embryonically

Answer 23

develops in 2 buds within ventral (front) and dorsal (back) mesentery

ductal systems fuse from both (if not have an accessory pancreatic duct)