LEC 24: Abdomen I Flashcards

1
Q

What are the organs of the digestive tube

A
  • mouth
  • pharynx and esophagus
  • stomach
  • small intestine (duodenum, jejunum, ileum)
  • large intestine (cecum, colon, rectum, anal canal, anus)
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2
Q

What are the accessory organs of the digestive tract

A
  • teeth
  • salivary glands
  • liver
  • pancreas
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3
Q

When does the primordial gut begin

A

Week 4

  • FGF signal A-P axial patterning
  • signals for induction of endoderm
    • FGF4 and activins
  • Endoderm: specifies temporal and positional information
  • stomodeum, proctodeum
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4
Q

What are the 5 classes of foregut derivatives

A
  • primordial pharynx and derivatives
  • lower respiratory system
  • esophagus and stomach
  • duodenum–PROXIMAL to bile duct
  • liver, billiary apparatus, pancreas
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5
Q

Where does the esophagus and stomach derive from

A

foregut

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6
Q

Where do the oral cavity, pharynx, tongue, tonsils, salivary glands, upper respiratory system derive from

A

foregut (primordial pharynx and derivatives)

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7
Q

Where does the duodenum derive from

A

foregut

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8
Q

Where do the liver, billiary apparatus, and pancreas derive from

A

foregut

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9
Q

Development of esophagus

A
  • T-E suptum separates esophagus
  • epithelium obliterates lumen and then it is recanalized
  • Upper 1/3: striated muscles from pharyngeal arches
    • move food down
  • Lower 1/3: smooth muscle from surrounding splanchnic mesenchyme
  • Cranial Nerve X (VAGUS)
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10
Q

What innervates the esophagus and what is the main supplier of blood flow

A
  • Cranial Nerve X (Vagus) innervates the esophagus
  • Celiac trunk is the primary blood supply to the esophagus
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11
Q

esophageal stenosis

A
  • incomplete recanalization of esophagus during 8th week

OR

  • failure of esophageal blood vessels to develop (atropy–lack of developing tissue causes dying)
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12
Q

When does the development of the stomach occur

A

Stomach development happens in week 4

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13
Q

Stomach development

A
  • dilation of tubular structure
  • fusiform enlargment
  • initially oriented in median plane
  • during weeks 4-6, broadens ventro-dorsally
    • dorsal boder grows faster, greater curvature forms
    • greater curvature toward vertebral column
    • lesser curvature towards anterior abdominal wall
    • surfaces are still left/right oriented
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14
Q

Rotation of stomach

A
  • Stomach, situated in median plane with greater curvature towards dorsal surface, lesser curvature toward ventral surface
  • rotates 90 degrees in a clockwise direction
    • lesser curvature (ventral border) moves right
    • greater curvature (dorsal border) moves left
    • original left side now ventral surface
    • original right side now dorsal surface
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15
Q

What nerves supply the walls of the stomach

A

LEFT VAGUS

  • supplies anterior wall

RIGHT VAGUS

  • supplies posterior wall
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16
Q

How is the stomach suspended in the abdomen

A

The stomach is suspended by dorsal mesogastrium (originally in median plane)

  • mesentary carried to the left during rotating
  • this forms omental bursa
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17
Q

omental bursa

A
  • clefts in dorsal mesogastrium coalesce to form omental bursa
  • with rotation, it is pulled to the left and stretched
  • allows free movement of stomach
18
Q

ventral mesogastrium

A
  • dorsal mesogastrium forms the omental bursa
  • ventral mesogastrium suspends the stomach and duodenum to liver and ventral abdominal wall
19
Q

What are the recesses formed by the dorsal mesogastrium

A
  • dorsal mesogastrium elongates to become the greater omentum
  • inferior recess disappears when layers fuse
20
Q

Congenital Pyloric Stenosis

A
  • 3/1000
    • males>females
  • stenosis of pyloric canal
  • obstruction of food
  • projectile vomiting
21
Q

What is the duodenum derived from

A

Duodenum has a dual origin and dual blood supply

FOREGUT

  • proximal to level of bile duct
  • blood supplied by celiac trunk

MIDGUT

  • blood supplied by superior mesenteric artery
22
Q

What is the blood supply to the duodenum

A

Duodenum derives from foregut (proximal to bile duct) and midgut

  • celiac artery supplies the foregut derived portion
  • superior mesenteric artery supplies midgut derived portion
23
Q

How does the duodenum rotate

A
  • duodenal loop projects ventral
  • with rotation, moves rightward
  • the lumen becomes obliterated and then recanalizes during weeks 5-6
24
Q

duodenal stenosis

A
  • partial occlusion of the lumen
  • due to incomplete recanalization from defective vacuolization
  • stomach contents (with bile) are vomited
25
Q

duodenal atresia

A
  • complete occlusion of duodenum
  • 20-30% associated with Down Syndrome
  • segment without recanalization
  • can happen in multiple sections of duodenum
  • “double-bubble” sign – polyhydramnios
    • backed up dilated duodenum because of atretic segment
26
Q

liver, gallbladder, and biliary apparatus

A
  • during week 4, outgrowth in foregut
  • Fibroblast growth factors (FGF) from heart –> bipotential cells –> hepatic diverticulum
  • hepatic diverticulum extends into septum transversum (from early embryo folding)
  • hepatic diverticulum divides into 2 parts
  • endodermal cells –> hepatic cords –> sinusoids
  • mesenchyme in septum transversum –> kupffer cells and hematopoetic tissue
27
Q

function of the gallbladder

A

emulsifies fatty foods

28
Q

Kupffer cells

A

macrophages derived from mesenchyme in septum transversum (get rid of bacteria)

29
Q

hematopoetic tissue

A

derived from mesenchyme in septum transversum (important for the formation of blood cells)

30
Q

significance of liver formation

A
  • right lobe is larger
  • hematopoiesis (begins around week 6)
  • bile formation (begins at week 12)
31
Q

What is the gallbladder formed from

A

small part of hepatic diverticulum forms the gallbladder

32
Q

What is the cystic duct formed from

A

stalk of diverticulum

33
Q

role of bile duct

A

connects hepatic and cystic ducts to duodenum

34
Q

Where is the entrance of the common bile duct

A

common bile duct moves posteriorly with stomach rotation

35
Q

ventral mesentary

A
  • lesser omentum
    • hepatogastric ligament
    • heaptoduodenal ligament
  • falciform ligament
  • forms visceral peritoneum of liver
36
Q

accessory hepatic ducts

A
  • extrahepatic biliary atresia
    • 1:10,000 to 1:15,000
    • failure of ducts to canalize or fetal infection
37
Q

development of pancreas

A
  • caudal foregut endodermal cells–>pancreatic buds (dorsal to ventral)
  • rotation of stomach, duodenum leads to pancreas lying on dorsal abdominal wall
  • ducts fuse to form main pancreatic duct
  • exocrine: endodermal tubules branch to form acinar cells and ducts
  • endocrine: clumps of cells from exocrine part form islets
38
Q

annular pancreas

A
  • growth of bifid ventral pancreatic bud around duodenum
  • can cause duodenal obstruction
39
Q

Where does the spleen develop from

A
  • spleen develops from mesenchyme in dorsal mesogastrium
  • thickening of mesoderm in dorsal mesogastrium
  • mesenchymal cells differentiate
    • capsule, connective tissue, parenchyma
  • center for hematopoiesis
40
Q

accessory spleen

A
  • 10% of population
  • tail of pancreas is a gastrosplenic ligament