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Digestion And Metabolism > Development Of GI System > Flashcards

Development Of GI System Flashcards

1
Q

What are the derivatives of the foregut?

A

Derivatives of the Midgut
Duodenum distal to the major duodenal papilla,
Jejunum & Ileum; Cecum & Appendix, Ascending colon & right 2/3 of transverse colon

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2
Q

What are the derivatives of the hindgut?

A

Derivatives of the Hindgut

Left 1/3 of Transverse colon
Descending colon, Sigmoid colon & rectum Anal canal up to the pectinate line
Urinary bladder & most of Urethra

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3
Q

What parts of the viscera are supplied by the celiac artery?

A 
Esophagus
Stomach
Liver /Gall bladder
Pancreas
Spleen (developed in dorsal mesogastrium) 1⁄2 Duodenum (superior to the major papilla)
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4
Q

What parts of the of the blood supply of the superior mesenteric ?

A 
Duodenum distal to the major duodenal papilla Jejunum
Ileum
Cecum /appendix
Ascending colon
Right 2/3 of transverse colon
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5
Q

What parts of the viscera are supplied by the inferior mesenteric?

A

Left 1/3 of Transverse colon
Descending colon, Sigmoid colon & rectum
Anal canal up to the pectinate line

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6
Q

Explain formation of the primordial gut

A

Derived from the dorsal part of umbilical vesicle (yolk sac), within the folds of the embryo

Suspended in the peritoneal cavity by dorsal and ventral mesenteries.

The epithelial lining and glands are derived from yolk sac endoderm
Smooth muscle and connective tissue are derived from splanchnic mesoderm

Neural component derived from the migration of neural crest cells

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7
Q

What happens to the primitive gut after embryonic folding?

A

After the embryonic folding, intra- embryonic part of the umbilical vesicle (yolk sac) is divided into foregut (within head fold) Midgut & Hindgut (within tail fold)

Omphaloenteric duct (Yolk stalk / vitellointestinal duct) connects midgut to the umbilical vesicle

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8
Q

Describe the epithelial lining of the gut

A
  1. Hollow tube
  2. Epithelial proliferation fills the lumen by 8th week
  3. Vacuoles then appear
  4. The process of Recanalization (hollow –solid –hollow) occurs by 10th week

Stenosis: due partial failure of (re) canalization of epithelial proliferation in their lumen

Atresia [e.g. of esophagus / duodenum / biliary tract] due to complete failure of (re)canalization of epithelial proliferation in their lumen

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9
Q

What is the foregut?

A

Begins at the abdominal esophagus and ends inferior to the major duodenal papilla.
• Esophagus
• Stomach
• Liver /Gall bladder
• Pancreas
• Spleen (developed in dorsal mesogastrium)
• 1⁄2 Duodenum (superior to the major papilla)

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10
Q

What is the blod supply, dranage and lymphatic drainage of the foregut?

A

Arterial supply : Celiac Trunk
Venous drainage: Portal Venous System
Lymphatic drainage: Celiac Nodes

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11
Q

Describe the anatomy of the stomach

A

J shaped structure which has 2 openings:
• Cardia
• Plyoric

2 curvatures :
• Greater
• Lesser

2 surfaces (walls)
• Anterior
• Posterior

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12
Q

What are the regions of the stomach?

A

Cardiac region of the stomach is on the left

Pyloric region of the stomach is to the right

The stomach therefore has its axis running from above left to below right

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13
Q

Describe rhe development of the stomach

A

Distal part of the foregut shows a fusiform dilatation during 4th week which has :
Right & Left surfaces Anterior & Posterior borders

As the stomach increases in size the posterior border (greater curvature) grows faster than the anterior border (lesser curvature)

  • Rotates clockwise around its long axis for 90 degrees.
  • Anterior border becomes lesser curvature
  • Posterior border becomes greater curvature

Ventral border (lesser curvature) moves to the right; dorsal border (greater curvature) moves to the left

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14
Q

How is rotation impactful in the development of the stomach?

A

After rotation→long axis of the stomach lies almost transverse to the long axis of the body, left surface becomes anterior wall of the stomach and right surface becomes posterior wall

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15
Q

Summarize development of the stomach

A
  • Positional changes of the stomach are explained by assuming it rotates along a longitudinal and anterior posterior axis
  • The stomach rotates 90 degrees clockwise around its longitudinal axis causing the left surface to face anteriorly and its right surface to face posteriorly.
  • The vagus nerve initially on the left side of the stomach innervates the anterior wall and the right vagus nerve innervates the posterior wall.

Adult structure : the pyloric part of the stomach moves to the right and upward
the cardiac part of the stomach moves to the left and slightly downwards

• The stomach in its final position has its axis running from above left to below right.

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16
Q

How are dorsal and ventral mesogastrium formed?

A

Stomach is suspended from the dorsal wall of the abdominal cavity by dorsal mesentery→ dorsal mesogastrium [greater omentum, gastrosplenic ligament & splenorenal ligament]

Ventral mesogastrium attaches stomach & duodenum to the liver & ventral abdominal wall: [falciform ligament & lesser omentum]

17
Q

What is congenital hypertrophic pyloric stenosis ?

A

Narrowing (stenosis) of the lumen of pyloric canal caused by hypertrophy of the muscles in the pyloric region
• Incidence : 1/150 male infants, 1/750 female infants

18
Q

Whst wre the effectsof congenital hypertrophic pyloric stenosis?

A
  • Stomach becomes distended & its contents are expelled with force (projectile vomiting)
  • vomitus not bile stained (bile duct opens in 2nd part of duodenum)
19
Q

Describe the clinical and physiccal presentation of congenital hypertrophic pyloric stenosis

A

Clinical presentation
•Non bilious projectile vomiting
•Generally starts three weeks after birth or as late as 5 months after birth.
• After the vomitus the infant is hungry and wants to feed again.

Physical examination
Pyloric mass – olive shaped Visible gastric peristaltic wave

20
Q

Describr the imaging seen on cingenital hypertrophic pyloric stenosis

A

• Barium swallow shows an abnormal defect in filling in the region of the pyloric sphincter

• Ultrasound –thickening of the pyloric
sphincter.

21
Q

What is the duodenum?

A

Duodenum is the first and shortest portion of the small intestine that forms a C shape around the pancreas

22
Q

What are the parts of the duodenum?

A

Four parts:
1st (superior) part is horizontal and is referred to as the duodenal bulb

2nd (descending) part is the site of the junction of the foregut and midgut – where the hepatopancreatic duct enters the duodenum through the major duodenal papilla on the posterior medial wall.

3rd (horizontal) part located inferior to the pancreas

4th (ascending) part –it joins duodenojejunal flexure which is suspended from the posterior wall by the Ligament of Treitz- suspensory ligament of the duodenum

23
Q

Describe the development of the duodenum

A
  • The duodenum develops from the caudal part of the foregut and the cranial part of the midgut
  • As the stomach rotates, the duodenum takes on the form of a C-shaped loop and rotates to the right.
  • The rotation of the stomach along with the rapid growth of the head of the pancreas, swings the duodenum from the initial midline position to the right side of the abdominal cavity
  • The duodenum and head of the pancreas press against the dorsal body wall and become fixed in the retroperitoneal position (secondarily retroperitoneal)
  • Epithelial lining proliferates and fills the lumen by 8th week (temporary occlusion of lumen). 10th week the lumen reappears by canalization
24
Q

What is duodenal srenosis ?

A

Duodenal Stenosis – partial occlusion of lumen due to incomplete recanalization:

-leads to vomiting which is usually bile stained [if stenosis is distal to the bile duct opening]

25
Q

What is duodenal atresia?

A

Duodenal Atresia
– complete occlusion of lumen [failure to recanalize]
-Polyhydramnios
-Vomiting begins immediately after birth

26
Q

What is the double bubble sign of duodenal atresia?

A
  1. Air in the stomach is one bubble
  2. Air in the proximal duodenum is the
    second bubble
  3. Obstruction caused by narrowing of the lumen of the proximal duodenum
27
Q

Descrbe development of the liver and billiary apparatus

A

Hepatic diverticulum arises (4th week) from the caudal part of foregut→ extends into the septum transversum

Hepatic diverticulum divides into cranial & caudal parts. Larger cranial part forms the liver; caudal part forms gall bladder & cystic duct

28
Q

Whhat is the function of the major papilla (hepatopancreatic ampulla)?

A

Common opening for bile duct and pamcreatic duct

29
Q

What are the ports of the pamcreas?

A

The four parts of the pancreas

  1. Head and uncinate process
  2. Neck
  3. Body
  4. Tail
30
Q

What is the function of the main pancreatic duct?

A

The main pancreatic duct traverses the length of the gland to join the common bile duct at the hepatopancreatic ampulla. Together they drain into the duodenum at the major duodenal papilla

31
Q

Describe the development of pancreas

A

Pancreas develops from two endodermal buds (ventral & dorsal) from the distal end of the foregut

Dorsal bud appears first [26th day], ventral appears on the 28th day. Rotation and fusion of the buds occur by the 7th week

Pancreatic buds fuse when the duodenum rotates to the right

Dorsal pancreatic bud – forms upper part of the head, body and tail Ventral pancreatic bud – lower part of the head and uncinate process

32
Q

How does the pamcreatic duct develop?

A

Main pancreatic duct – develops from proximal part of the duct of ventral bud & distal part of the duct of dorsal bud

Accessory pancreatic duct – proximal part of the duct of dorsal pancreatic bud

33
Q

What is an annular pancreas?

A

Annular Pancreas – probably due to bifid ventral pancreatic bud. The ventral pancreatic bud consists of two components that normally fuse and rotate around the duodenum so that they come to lie below the dorsal pancreatic bud.

Occasionally, the right portion of the ventral bud migrates along the normal route, but the left migrates in the opposite direction. A ring of pancreatic tissue encircles the second part of duodenum and causes obstruction

34
Q

What does the spleen develop from?

A

The spleen is not an outgrowth of foregut. The spleen is derived from mesenchymal cells between the layers of dorsal mesogastrium (5th week).

Spleen is lobulated in the fetus

Digestion And Metabolism (57 decks)

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