Embryology And Anatomy ✅

Question 1

When does the human GI tract first appear?

Answer 1

4 weeks gestation

Question 2

When is the human GI tract complete?

Answer 2

12 weeks gestation

Question 3

What does the embryo consist of at 4 weeks gestation?

Answer 3

3 parts - the endoderm, ectoderm, and mesoderm

Question 4

What does the endoderm give rise to in the GI tract?

Answer 4

The lining of the GI tract

Question 5

What does the mesoderm give rise to in the GI tract?

Answer 5

The smooth muscle

Question 6

What does the ectoderm give rise to in the GI tract?

Answer 6

The enteric nervous system

Question 7

How is embryonic folding involved in the formation of the GI tract?

Answer 7

Initial folding results in a tubular structure with craniocaudal distribution. Further folding results in the cranial and caudal sections forming into blind-ended tubes

Question 8

What do the blind-ended tubes formed in embryonic folding later become?

Answer 8

The foregut and hindgut

Question 9

What separates the blind-ended tubes that later become the foregut and hindgut?

Answer 9

A section which is still attached to the yolk sac

Question 10

What does the section that is still attached to the yolk sac later become?

Answer 10

The midgut

Question 11

What happens to the yolk sac as the embryo develops further?

Answer 11

The yolk sac becomes smaller, and the midgut becomes a separate structure

Question 12

Is the midgut still attached to the yolk sac when it becomes a separate structure?

Answer 12

Yes

Question 13

How is the midgut still attached to the yolk sac after it becomes a separate structure?

Answer 13

Via the Vitelli email duct

Question 14

What structures are formed from the foregut?

Answer 14

• Pharynx
• Oesophagus
• Stomach
• Proximal duodenum

Question 15

What structures are formed from the midgut?

Answer 15

• Distal duodenum
• Small bowel
• Distal colon

Question 16

What structures are formed from the hindgut?

Answer 16

• Distal colon

- Rectum

Question 17

What happens to the intestines throughout development?

Answer 17

It undergoes a number of changes in position

Question 18

What happens to the intestines at week 5?

Answer 18

It elongates and begins to form a loop, which protrudes into the umbilical cord

Question 19

What has happened to the position of the GI tract by week 6?

Answer 19

The stomach and duodenum have rotated 90 degrees clockwise

Question 20

What happens to the intestines at week 8?

Answer 20

The duodenum and jejunum herniate further from the abdominal cavity, and rotate around the axis of the superior mesenteric artery by 90 degrees, and take up a position behind the superior mesenteric artery

Question 21

What direction does the duodenum and jejunum rotate around the axis of the superior mesenteric artery?

Answer 21

Counterclockwise

Question 22

What happens to the intestine at week 11?

Answer 22

The intensive retracts into the abdomen

Question 23

What is the control mechanism behind the intestine retracting into the abdomen at week 11?

Answer 23

Unknown

Question 24

In what order does the intestine return to the abdomen in week 11?

Answer 24

The jejunum returns first, then ileum, then rest of small intestine, then colon

Question 25

Where in the abdomen does the jejunum return to?

Answer 25

The left half

Question 26

Where in the abdomen does the ileum return to?

Answer 26

The right half

Question 27

What happens to the position of the intestines by the end of week 11?

Answer 27

The caecum has moved downwards and the intestines have reached their final adult position

Question 28

When does the intestinal endoderm begin to differentiate?

Answer 28

Only after the final position of the intestines is reached (aka after week 11)