Development Of Gut 1,2 Flashcards

1
Q

What parts of GI make up the the;

  • Foregut
  • Midgut
  • Hindgut
A

F: Oesophagus to Duodenum

M: Duodenum to Distal 2/3 of Transverse Colon

H: Distal 2/3 of Transverse Colon to Anus

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2
Q

What is the Vitelline duct?

What happens to it before birth

A

Connection between Midgut and Yolk Sac

Completely obliterates

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3
Q

List 2 abnormalities when the Vitelline Duct does not obliterate by birth

A
  • Presence of a Meckel’s Diverticulum (Outpuch of Small Intestine)
  • Connection between Midgut and Umbilicus (Fecal material comes out through Umbilicus)
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4
Q

What 2 types of folding occur in week 4?

What are the results of these?

A

Lateral:

  • Creates ventral body wall (anterior body wall)
  • Primitive gut becomes tubular (gut tube)

Craniocaudally:
- Creates cranial and caudal pockets/ head and tail ends (from yolk sac endoderm)

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5
Q

What is the Gut Tube that is made from Lateral Folding?

Where does it open? What is it covered by?

A
  • An endoderm lined tube
  • running the length of the body
  • with blind pouches at head and tail ends
  • Opens at Umbilicus
  • Covered by Splanchnic (Visceral) Mesoderm
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6
Q

Compare the Splanchnopleuric and Somatopleuric mesoderm

What is the space between them called

A
  • Splanchnopleuric: Combination of Splanchnic Mesoderm and Endoderm (of Gut tube)
  • Somatopleuric: Combination of Somatic Mesoderm and Ectoderm
  • Intraembryonic Coelom
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7
Q

What will the Intraembryonic Coelom eventually turn into?

How does it develop into this stage? (Very briefly)

A
  • Begins as one large cavity

- Later divided by Diaphragm into Thoracic and Abdominal Cavities

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8
Q

Describe the Intraembryonic Coelom’s membrane

A
  • 1 membrane lining whole cavity

- Specialises as cavities specialise into Pleura/ Pericardium/ Peritoneum and peritoneal cavity

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9
Q

What parts of the Peritoneum do the Somatic and Splanchnic Mesoderm develop into?

What is the space between called?

A

Splanchnic- Visceral
Somatic- Parietal

  • Space between called the Peritnoneal Cavity (Is only a potential space, should be empty normally)
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10
Q

In the 4th week, what Membrane breaks, to effectively give us a “mouth”

A

Buccopharyngeal Membrane

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11
Q

In the 7th week, what membrane breaks, to effectively give us an “anus”

A

Cloacal membrane

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12
Q

What branches of the Abdominal Aorta supply each segment of the GI Tract?

A

Coeliac artery- Foregut
Superior Mesenteric- Midgut
Inferior Mesenteric- Hindgut

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13
Q

Name 1 non-GI derivative of the Foregut

A

Respiratory tract

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14
Q

What does the endoderm of the gut do in the 5th and 9th weeks?

A

5th: Proliferates rapidly, temporarily closing lumen
9th: Recanalises (Opens lumen again)

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15
Q

What happens in the Foregut in 4th week?

A
  • A lung bud (respiratory diverticulum) forms ventrally

- A Tracheoesophageal Septum forms, separating Trachea and Oesophagus

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16
Q

Abnormal positioning of the Tracheoesophageal Septum occurs in about 1 in 3000 births and can lead to a variety of abnormalities

Name 2

A
  • Blind end Oesophagus (Ends suddenly, doesn’t continue)

- Tracheoesophageal Fistula (Abnormal connection between the 2)

17
Q

The stomach is simply a dilation of the foregut

Does it dilate more on the Anterior or Posterior aspect?

What happens next?

A

Posterior

Rotates by 90 degrees

18
Q

What Mesenteries attach the Gut Tube to the body walls?

A
  • Dorsal mesentery attaches ENTIRE gut tube to dorsal body wall
  • Ventral mesentery attaches ONLY Foregut to ventral body wall
19
Q

What is the Free Edge of the foregut?

A

The lower edge of the Ventral Mesentery of the Foregut

20
Q

Which organs develop in the Ventral and Dorsal mesentery?

A

Ventral- Liver
Spleen- Dorsal

(Obviously the dorsal mesentery is rotated to the left and ventral to the right)

21
Q

The liver develops as a bud off of the anterior foregut

What do the cranial and caudal portions of the bud develop into?

A

Cranial- Liver (Connection remains as Bile Duct)

Caudal- Gall bladder

22
Q

The dorsal and ventral mesenteries of the foregut divide the peritoneal cavity into Left and Right Sacs (in this region only)

Which sac contributes to the Greater and Lesser sacs?

A

Left sac- Contributes to Greater sac

Right sac- Contributes to Lesser sac

23
Q

Why is the Lesser sac much smaller than Greater?

A

Liver grows and takes up space

24
Q

Which sacs lie Anterior and Posterior to stomach?

A

Lesser sac lies posterior to stomach

Greater sac lies anterior to stomach

25
Q

What is the Foramen of Winslow/ Epiploic Foramen?

A

A small connection between Lesser and Greater sacs, formed by the Free Edge of the Foregut

26
Q

The vagus nerves initially lie left and right to the stomach.

How does their position change after the stomach’s rotation?

A

Left vagus fibres lie anterior to stomach

Right vagus fibres lie posterior to stomach (In lesser sac)

27
Q

Name and describe the 2 remnants of the Ventral Mesentery of the Foregut

(They are both double folds of Peritoneum)

A
  1. Falciform Ligament: From Anterior Abdominal wall to Liver
  2. Lesser Omentum: From Liver to Stomach
28
Q

Name and describe the 2 remnants of the Dorsal Mesentery of the Foregut

(They are both double folds of Peritoneum)

A
  1. Gastro-splenic ligament: From Stomach to Spleen

2. Spleno-renal Ligament: From Spleen to Left Kidney

29
Q

What are omenta?

A

Specialised regions of peritoneum

30
Q

The Greater Omentum is formed from the Dorsal mesentery.

What structures does it connect together?

A

Stomach and transverse colon

31
Q

Describe the development of the Pancreas

A
  • Starts as a Smaller Ventral and Larger Dorsal Buds off of Foregut
  • Ventral head rotates to become inferior to Dorsal Bud
32
Q

Describe the development of the Duodeum

A
  • Develops from Caudal Foregut and Cranial Midgut
  • Stomach rotation pushes Duodenum to right, then against posterior abdominal wall
  • It has now become Secondary Retroperitoneal
33
Q

What is a Secondary Retroperitoneal structure?

A
  • One that developed intraperitoneally
  • whose mesentery was lost to fusion with Post. Ab Wall Parietal Peritoneum
  • due to massive GI tract expansion during development