Development of the digestive tract AHS1

Question 1

What is gastrulation?

Answer 1

Formation of the trilaminar germ disc/three layers

Question 2

What are the two different types of lateral plate mesoderm?

Answer 2

Somatic and splanchnic

Question 3

What area of the body is somatic lateral plate mesoderm?

Answer 3

Body wall

Question 4

What area of the body is splanchnic lateral plate mesoderm?

Answer 4

Viscera

Also muscle layers of the gut tube (even though rest of GI tract is endoderm)

Question 5

What does the ectoderm make?

Answer 5

Nervous system, adrenal medulla, skin

Question 6

What does the mesoderm make?

Answer 6

Bone, cartilage, muscles, CV system, limbs, UG tract, spleen

Question 7

What does the endoderm make?

Answer 7

The lining of the gut, GI tract accessory organs (liver, pancreas etc.). respiratory tract (the parts of the body that have openings to the outside)

Question 8

What layer are the lips derived from?

Answer 8

The ectoderm

Question 9

What layer are the mucous membranes

Answer 9

Endoderm

Question 10

What is the area where the endoderm and ectoderm come in contact to form the mouth called?

Answer 10

Oro-pharangeal membrane

Question 11

What is the area where the endoderm and ectoderm come in contact to form the anus called?

Answer 11

Anal membrane

Question 12

What does the septum transversum form?

Answer 12

The diaphragm and cranioventral mesentery

Question 13

What mesenteries does the foregut have?

Answer 13

Dorsal and ventral mesentery

turn into mesoduodenum etc. when the GI tract starts to differentiate into different parts

Question 14

What mesenteries does the midgut have?

Answer 14

Only a dorsal mesentery (due to amniotic sac formation)

Question 15

What mesenteries does the hindgut have?

Answer 15

Dorsal and ventral mesenteries

Question 16

How does the stomach start to develop?

Answer 16

By forming a bulge dorsally in the GI tract

Question 17

Where does the spleen develop from?

Answer 17

From the mesoderm (rather than the endoderm like the GI tract)

Question 18

Where does the spleen develop in the abdomen?

Answer 18

In the dorsal mesogastrium/mesentery

Question 19

How does the stomach further develop in the abdomen/twist?

Answer 19

It rotated 90 degrees anticlockwise around the cranio-caudal axis so that the greater curvature is on the left (or right looking ventrally).
It then rotates 45 degrees to run more transversely so top is on the left and bottom is on the right.

Question 20

How are the other organs affected by the rotation of the stomach?

Answer 20

The spleen in the dorsal mesentery is pulled to the left as the greater curvature of the stomach is pulled to the left
The liver in the ventral mesentery is pulled slightly to the right

Question 21

How does the greater omentum form?

Answer 21

The dorsal mesogastrium/mesentery comes off the greater curvature of the stomach and folds back on itself

Question 22

How does the lesser omentum form?

Answer 22

From the ventral mesogastrium running cranially to the liver from the lesser curvature of the stomach (the stomach curls round)

Question 23

Where do the liver and pancreas arise from?

Answer 23

From the gut tube near the foregut/midgut boundary

Question 24

Why is the liver closely associated with the diaphragm?

Answer 24

Because the liver bud invades the septum transversum

Question 25

What is the septum transversum?

Answer 25

Cranial mesenchyme that gives rise to the diaphragm and the ventral mesentery of the foregut

Question 26

How do stomach rotations affect the pancreas?

Answer 26

They bring the pancreatic buds together to fuse to form a single pancreas with two lobes

Question 27

In what animals are there separate openings of the common bile duct and accessory pancreatic duct?

Answer 27

Dog, horse and human - others are different with either pancreatic ducts and bile ducts sharing one opening of two completely separate ducts

Question 28

How does the midgut twist in development?

Answer 28

It extends into the umbilicus It then twists 180 degrees clockwise around the root of the mesentery It then retracts back into the abdomen and twists another 90 degrees

Question 29

Where is the caecum located in the abdomen?

Answer 29

On the right hand side

Question 30

Which way does the transverse colon pass behind the root of the mesentery?

Answer 30

From the right to the left

Question 31

Which side of the abdomen is the descending colon on?

Answer 31

The left side | right side looking ventrally

Question 32

How does the hind gut develop?

Answer 32

The reproductive tract and the GI tract separate and the anal membrane breaks to form a hole

Question 33

What are the complications with hindgut formation?

Answer 33

Anal atresia - anal membrane doesn't break down

Question 34

What are the main vessels of the umbilicus?

Answer 34

Umbilical arteries and umbilical vein

Question 35

What does the umbilical vein do?

Answer 35

Takes oxygenated blood from the mother into the foetus

Question 36

Where does the umbilical vein lead?

Answer 36

Into the ductus venosus

Question 37

What do the umbilical arteries do?

Answer 37

Carry the deoxygenated blood out of the foetus

Question 38

Where are the umbilical arteries?

Answer 38

Next to the urachus

Question 39

What is the urachus?

Answer 39

Primitive bladder - takes the urine in the foetus down the umbilicus form the bladder to the allantois

Question 40

What happens to the urachus after birth?

Answer 40

The lower part shrivels up and the upper part forms the bladder

Question 41

What does the umbilical vein turn into?

Answer 41

The teres/round ligament

Question 42

What is the falciform ligament?

Answer 42

A fold in the ventral mesogastrium/peritoneum that is full of fat

Question 43

Where is the falciform ligament located?

Answer 43

Next to the teres ligament cranial to the umbilicus

Question 44

What do the umbilical arteries turn into?

Answer 44

The proximal part - cranial vesicle arteries | The distal part - round ligaments of the bladder

Question 45

What are the cranial vesicle arteries?

Answer 45

Arteries that supply the bladder that are derived from the umbilical arteries

Question 46

What does vesicle mean?

Answer 46

Bladder

Question 47

What are the ligaments that form around the bladder?

Answer 47

The lateral vesicle ligaments and the median vesicle ligament

Question 48

What are the lateral vesicle ligaments derived from?

Answer 48

Folds in the ventral mesogastrium/peritoneum around the umbilical arteries

Question 49

Where is the median vesicle ligament derived from?

Answer 49

A fold in the ventral mesogastrium/peritoneum which comes up from the ventral peritoneum