Development of alimentary (digestive) system

Question 1

What is gastrulation?

Answer 1

A single layered blastula –> trilaminar gastrula forming the 3 germ layers

Question 2

What are the 3 germ layers?

Answer 2

Ectoderm, mesoderm and endoderm

Question 3

What are the general components of the alimentary system and where does it run from?

Answer 3

Mouth to anus (the tract) with associated glands and organs eg liver, gallbladder, pancreas

Question 4

What week does the primordial gut from?

Answer 4

Week 4

Question 5

What are the 2 ends of the primordial gut called and what end is broader?

Answer 5

Cranial and caudal with the cranial end being broader

Question 6

What is the cranial end of the primordial gut closed by?

Answer 6

Oropharnygeal membrane

Question 7

What is the caudal end of the primordial gut closed by?

Answer 7

Cloacal membrane

Question 8

As the head and tail folds what part is taken in by the embryo?

Answer 8

Yolk sac

Question 9

Name the 3 parts of the primordial gut tube

Answer 9

foregut, midgut and hindgut

Question 10

What part of the primordial gut forms most of the gut, epithelium and glands

Answer 10

Endoderm

Question 11

What does the intraembryonic coelom give rise to?

Answer 11

Embryonic body cavity

Question 12

What will the embryonic cavity give rise to?

Answer 12

Peritoneum, pericardium and pleural cavities

Question 13

What are the constituents of the foregut?

Answer 13

Primordial pharynx, LRT, oesophagus, stomach, duodenum, liver, biliary apparatus and pancreas

Question 14

What does the tracheoesophageal ridge divide?

Answer 14

Divides the trachea and oesophagus

Question 15

Oesophageal atresia is due to what?

Answer 15

The oesophagus not growing properly

Failure of recanlization

Question 16

What is polyhydraminios

Answer 16

The accumulation of excess amniotic fluid

Question 17

What is a tracheosophageal fistula?

Answer 17

Trachea and oesophagus communicate due to the abnormal deviation of septum

Question 18

What degrees and in which direction does the stomach rotate?

Answer 18

90, clockwise

Question 19

What is the dorsal mesogastrium?

Answer 19

The portion of the dorsal mesentery attached to the greater curvature of the stomach

Question 20

What does the dorsal mesogastrium develop into?

Answer 20

Greater omentum

Question 21

When the stomach rotates to the left, a space is made behind the stomach? What does this become?

Answer 21

Lesser omentum/ omental bursa

Question 22

What nerves supply the liver?

Answer 22

vagus (left and right)

Question 23

What is hypertrophic pyloric stenosis?

Answer 23

When the child will vomit everything up as the pyloric sphincter is enlarged

Question 24

What are some common causes of hypertrophic pyloric stenosis?

Answer 24

monozygotic twins
Higher in males
Genetics

Question 25

What does the hepatic diverticulum give rise to?

Answer 25

Liver - sinusoids and vessels

Question 26

Briefly describe 2 anomalies of the liver

Answer 26

Accessory hepatic ducts | Extra hepatic biliary atresia - obliteration of bile ducts

Question 27

How do the 2 buds of the pancreas join?

Answer 27

Ventral and dorsal buds join due to the rotation of the stomach

Question 28

Which parts of the pancreas do the ventral and dorsal buds make?

Answer 28

Head | most of pancreas

Question 29

What is annular pancreas?

Answer 29

The ventral bud fails to migrate around the duodenum properly causing stenosis

Question 30

What is accessory pancreatic tissue?

Answer 30

Pancreatic tissue in other parts of the foregut

Question 31

What week does the dorsal mesogastrium develop?

Answer 31

week 4

Question 32

What week does the mesenchyme form the spleen?

Answer 32

week 5

Question 33

Is the spleen mesodermal or endodermal derivative?

Answer 33

mesodermal

Question 34

Name the parts of the midgut

Answer 34

Duodenum (distal part), jejunum, ileum, caecum, appendix, ascending colon, proximal 2/3 transverse colon

Question 35

State the 4 stages of the midgut looping

Answer 35

Herniation, rotation, retraction and fixation

Question 36

What kind of herniation is involved in gut looping and briefly explain

Answer 36

The midgut herniates into the umbilical cord (yolk sac)

Question 37

What degrees does the midgut loop in umbilical cord?

Answer 37

90 degrees counter clockwise

Question 38

What degrees does the midgut loop retract?

Answer 38

180 degrees counterclockwise

Question 39

What degrees does the stomach and midgut loop rotate?

Answer 39

90 degrees clockwise | 270 degrees anticlockwise

Question 40

What is formed if the vitelline duct persists?

Answer 40

Meckel diverticulum due to narrowing of ileum lumen

Question 41

What can form from the persistence of the vitelline duct?

Answer 41

fistula, vitelline cyst/ ligament

Question 42

What does the vitelline duct join?

Answer 42

Yolk sac to midgut lumen

Question 43

What is omphalocele?

Answer 43

The herniation of abdominal viscera through an enlarged umbilical ring due to the failure of retraction of herniated loops

Question 44

What organs are often involved with omphalocele?

Answer 44

Liver, stomach and intestinal loops

Question 45

What are the organs protruding in omphalocele enclosed by?

Answer 45

Amnion layer covering the viscera

Question 46

What is gastroschisis?

Answer 46

A muscular defect with the herniation of abdominal contents through the body wall into the amniotic cavity

Question 47

What causes gastrochisis and what are the thought causes?

Answer 47

The contents are returned to the abdomen but enter back into the umbilicus Cocaine and tobacco use

Question 48

Name the parts of the hindgut

Answer 48

distal 1/3 of transverse colon, descending colon, sigmoid colon, rectum, upper part of anal canal

Question 49

What does the endoderm of hindgut also go on to make?

Answer 49

Bladder and urethra lining

Question 50

What is the cloaca?

Answer 50

The expanded terminal part of the hindgut and endoderm lined chamber

Question 51

What is the allantois?

Answer 51

The ventral part (diverticula) of the cloaca

Question 52

What is the cloacal membrane?

Answer 52

Separates cloaca and anal pit

Question 53

What week does the cloacal membrane rupture?

Answer 53

End of week 7 for an opening

Question 54

What is the job of the urorectal septum?

Answer 54

To divide the rectum and bladder | hindgut and urogenital sinus

Question 55

The proliferation of what causes the closing of the claudal end?

Answer 55

Ectoderm of anal canal

Question 56

When does the anal canal reopen?

Answer 56

week 9

Question 57

What is imperforate anus?

Answer 57

When the anal membrane fails to break down