Embryology And Anatomy ✅ Flashcards Preview

TAS Gastroenterology > Embryology And Anatomy ✅ > Flashcards

Flashcards in Embryology And Anatomy ✅ Deck (28)
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1
Q

When does the human GI tract first appear?

A

4 weeks gestation

2
Q

When is the human GI tract complete?

A

12 weeks gestation

3
Q

What does the embryo consist of at 4 weeks gestation?

A

3 parts - the endoderm, ectoderm, and mesoderm

4
Q

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

A

The lining of the GI tract

5
Q

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

A

The smooth muscle

6
Q

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

A

The enteric nervous system

7
Q

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

A

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

8
Q

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

A

The foregut and hindgut

9
Q

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

A

A section which is still attached to the yolk sac

10
Q

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

A

The midgut

11
Q

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

A

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

12
Q

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

A

Yes

13
Q

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

A

Via the Vitelli email duct

14
Q

What structures are formed from the foregut?

A
  • Pharynx
  • Oesophagus
  • Stomach
  • Proximal duodenum
15
Q

What structures are formed from the midgut?

A
  • Distal duodenum
  • Small bowel
  • Distal colon
16
Q

What structures are formed from the hindgut?

A
  • Distal colon

- Rectum

17
Q

What happens to the intestines throughout development?

A

It undergoes a number of changes in position

18
Q

What happens to the intestines at week 5?

A

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

19
Q

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

A

The stomach and duodenum have rotated 90 degrees clockwise

20
Q

What happens to the intestines at week 8?

A

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

21
Q

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

A

Counterclockwise

22
Q

What happens to the intestine at week 11?

A

The intensive retracts into the abdomen

23
Q

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

A

Unknown

24
Q

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

A

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

25
Q

Where in the abdomen does the jejunum return to?

A

The left half

26
Q

Where in the abdomen does the ileum return to?

A

The right half

27
Q

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

A

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

28
Q

When does the intestinal endoderm begin to differentiate?

A

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