Development of the GI System Flashcards

1
Q
  • Epithelium and glands come from _
  • Mouth and anal canal come from _
  • Smooth muscle and connective tissue come from _
  • Autonomic ganglion come from _
A
  • Endodern
  • Ectoderm
  • Splanchnic mesoderm
  • Neural Crest Cells
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2
Q
  • What are the divisions of the digestive system?
A
  • Foregut
    • Above yolk sac
  • Midgut
    • Where yolk sac is attached
  • Hindgut
    • Below yolk sac
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3
Q
  • Components of the foregut
  • What vessels supply the foregut ?
A
  • Foregut
    • Pharynx
    • Respiratory system
    • Esophagus
    • Stomach
    • Liver and pancreas
    • Biliary apparatus
    • Proximal duodenum
  • Celiac trunk
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4
Q
  • What anatomial structure helps to separate the foregut and the midgut?
A
  • Major duodenal papilla
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5
Q
  • What are the components of the midgut?
  • What vessels supply the midgut?
A
  • Midgut:
    • Small intestine
    • Cecum and veriform appendix
    • Ascending colon
    • Right half of transverse colon
  • Superior mesenteric a.
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6
Q
  • What are the components of the hindgut?
  • What vessels supply the hindgut?
A
  • Left half of transverse colon
  • Descending colon
  • Sigmoid colon
  • Rectum
  • Superior anal canal
  • Epithelium of urinary bladder/urethra
  • Inferior mesentary a.
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7
Q
  • What germ layer makes up the smooth muscle components of the esophagus?
  • What germ layer makes up the striated/skeletal muscle of the esophagus?
A
  • Splanchnic Layer of the Lateral Plate Mesoderm
  • 4th and 6th Pharyngeal Arches (mesoderm)
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8
Q
  • Embryological mechanism of TE fistula
  • What week did this happen?
  • Presenting signs and symptoms
A
  • Failure of tracheoesophageal folds to fuse and form tracheoesophageal septum
  • WK 5
  • Prenatally:
    • Polyhydramnios
  • Birth:
    • Coughing
    • Gagging
    • Cyanosis
    • Vomiting
    • Voluminous oral secretions
    • Respiratory distress
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9
Q
  • Stomach starts developing during week _
  • Rotation causes right vagus to be _ and left vagus to be _
  • The ventral border of the stomach is to the _
  • The dorsal border of the stomach is to the _
  • Left side of the stomach is _
  • Right side of the stomach is _
A
  • 4
  • Right=Posterior, Left=Anterior (LARP)
  • Right
  • Left
  • Ventral
  • Dorsal
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10
Q
  • Hypertrophic pyloric stenosis
A
  • Circular and longitudinal muscles of the pylorus hypertrophy
  • Presentation:
    • ​Immediate post-feeding vomiting that is non-bilious (proximal to major duodenal papilla)
    • Forceful, projectile vomiting
    • Fewer and smaller stools
    • Failure to gain weight
  • If it gets too severe
    • Can feel mass on L1 (at the transpyloric plane (level of the pylorus))
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11
Q

Development of the liver and biliary system:

  • Ventral outgrowth of the hepatic diverticulum grows superiorly towards _
  • Hepatic diverticulum components?
  • Bile is being produced by week _
  • Hematopoesis in liver occuring from Wks _ to _
A
  • Septum transversum
  • Hepatic diverticulum consists of:
    • Liver
    • Gallbladder
    • Ventral pancreatic bud
  • 12
  • 6-30
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12
Q
  • The main functional cells of the liver and pancreas come from what germ layer?
  • The Keppler cells, stroma and myocytes in the liver come from _
A
  • Endoderm
  • Mesoderm
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13
Q
  • As the duodenum rotates to the right the _ pancreatic bud is carried dorsally and fuses with the _ pancreatic bud
  • Main pancreatic duct comes from the _ pancreatic bud
A
  • Ventral, dorsal
  • Ventral
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14
Q
  • Annular pancreas:
    • Embryological mechanism
    • Symptoms are similar to symptoms of _
A
  • Annular pancreas can lead to obstruction of the duodenum
  • Symptoms similar to pyloric stenosis (vomit can be bilious though if the obstruction is inferior to the major duodenal papilla) 2/3 patients are asymptomatic
  • Embryological mechanism is:
    • Ventral pancreatic bud is bifed and rotates left instead of right
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15
Q
  • Spleen is made from what germ layer
  • It is hematopoetic from weeks _ to _
A
  • Mesoderm
  • 9-28
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16
Q
  • The midgut is continuous with the _ duct and extends into the _
  • Rotation occurs outward at WK _ and back inwards at WK _
  • The _ artery is the axis about which the midgut rotates
  • Total of _ degrees of roation
  • Cranial part of the axis forms the _
  • Caudad part of the axis forms the _
A
  • Vitelline, umbilical cord
  • 6, 10
  • Superior mesentaric artery
  • 270
  • SI
  • LI (cecum)
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17
Q
  • Omphalocele
A
  • Failure of bowel to return to body cavity
  • Occurs during WK 10
  • NOT AN UMBILICAL HERNIA
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18
Q
  • Gastroschisis
A

​Failure of the body wall to close during WK 4-herniation of abdominal contents

Typically occurs on the right side

19
Q
  • Hirschprung’s Disease/Congenital Megacolon
A
  • Embryological mechanism: NCCs
  • Absence of ganglion cells (parasympathetics) which leads to constriction points along the GI tract (sympathetics taking over)
  • Areas that contain feces do have ganglion cells/parasympathetics present
20
Q
  • Congenital diaphragmatic hernia
A
  • Herniation of abdominal contents into thoracic cavity
  • Happens b/c pleuroperitoneal canals do not duse with septum transversum
  • Large opening in posterolateral diaphragm (Foramen of Bochdalek)
  • 85-90% occur on left side
  • Characteristics
    • Hypoplastic lungs
    • Polyhydramnios
21
Q
  • Midgut non-rotation
A
  • SI on right
  • LI on left
  • Some asymptomatic
  • Increased likelihood of obstruction d/t tighter turns
22
Q
  • Mid-gut reversed rotation
A
  • Transverse colon is posterior to the duodenum
  • Common to have obstructions in the transverse colon
23
Q
  • Formation of the definitive gut lumen
A
  1. Hollow gut tube
  2. Endothelial lining proliferates
  3. Recanalization
  4. Creation of definitive hollow gut tube

What can go wrong:

  • Duplication (not true diverticulum, but can accumulate food and lead to wall rupture)
  • Stenosis (apoptosis did not occur correctly; leads to narrowing of canal and increased likelihood of obstruction)
24
Q
  • Meckel’s Diverticulum
A
  • Abnormality of the vitelline duct (which normally regressesm but instead it is pulling on the ileum)
  • Projection of ileum to abdominal wall
  • Can lead to intestinal obstructionm GI bleeding, Bowel Sepsis

RULE OF 2s:

  • 2% pop, 2 x more likely males, Age 2
  • 2 ft inferior to ileocecal junction
  • 2 in long
  • 2 types of ectopic tissue (gastric and pancreatic)
25
Q
  • Omphalomesenteric fistula
A
  • Vitellointestinal duct remains open
  • Feces coming out of umbilicus
26
Q
  • Omphalomesenteric cyst
A
  • Usually detected post-mortum
  • Cyst develops in vitelline duct
27
Q
  • Omphalomesenteric ligament
A
  • Fibrous band connecting ileum to umbilicus but didn’t pull enough on ileum to cause a diverticulum
28
Q
  • The cloacal membrane is made of what two germ layers?
  • _ septum grows towards the cloacal membrane and divides the hindgut into the:
    • Urogenital membrane
    • Anal Membrane
  • The urorectal septum is made of _ and the urofenital and anal membranes are made of _ and _
A
  • Ectoderm and endoderm
  • Urorectal
  • Mesoderm, endoderm and ectoderm
29
Q
  • The urorectal septum comes from the _
A
  • Perineal body
30
Q
  • The _ line separates the superior and inferior anal canal
  • The superior anal canal comes from _ and is supplied by which lymph and neurovascular structures?
  • The inferior anal canal comes from _ and is supplied by which lymph and neurovascular structures?
A
  • Pectinate
  • Hindgut endoderm, inferior mesenteric artery, autonomic nerves and inferior mesenteric LNs
  • Ectoderm and endoderm, middle and inferior rectal arteries, pudendal nerve, superficial inguinal LNs
31
Q
  • Anorectal malformations
A
32
Q
  • What are the three body cavities?
A
  • Pericardial
  • Pleural (2)
  • Peritoneal
33
Q
  • Formation of the pleural-peritoneal membrane occurs when pleuro-peritoneal membranes fuse with the _
  • What germ layer is this made from?
A
  • Septum transversum
  • Somatic layer of the lateral plate mesoderm
34
Q
  • The septum transversum forms the _ of the diaprhagm
  • The dorsal mesentary of the esophagus is also known as the _
A
  • Central tendon
  • Crura
35
Q
  • Mesentary is a double layer of _ and allows blood vessels, nerves, and lymphatics to reach organs
  • _ mesentary is attached to posterior body wall
  • _ mesentary is attached to the anterior body wall (most of it degenerates)
  • Visceral layer of the peritoneal cavity comes from _ mesoderm
  • Parietal layer of the peritoneal cavity comes from _ mesoderm
A
  • Serous membrane/splanchnic mesoderm
  • Dorsal
  • Ventral
  • Splanchnic
  • Somatic
36
Q
  • Regional specializations of the mesentaries
  • Thoracic esophagus and anus are _
A
  • Foregut and heart
  • Abdominal Cavity and Liver
  • Midgut and Hindgut
  • Retroperitoneal
37
Q
  • What makes up the dorsal mesogastrium?
A
  • Splenorenal (leinorenal ligament)
  • Gastrolienal ligament
  • Greater omentum

Attaches posterior body wall to stomach

38
Q
  • What makes up the ventral mesogastrium?
A
  • Lesser omentum
39
Q
  • What makes up the ventral mesentary?
A
  • Falciform ligament (liver to anterior abdominal wall)
40
Q
  • The greater omentum comes from _ mesogastrium and has _ layers
A
  • Dorsal
  • 4
41
Q
  • Fusion of mesentaries with body walls results in _ structures
A
  • Secondary retroperitoneal
42
Q
  • What are some examples of secondary retroperitoneal structures?
A
  • Mesogastrium dorsal to spleen
  • Mesoduodenum
  • Ascending mesocolon
  • Descending mesocolon
43
Q
  • Intraperitoneal structures
A
  • Stomach
  • Tail of pancreas
  • First part of duodenum
  • Jejunum, Ileum
  • Transverse Colon
  • Sigmoid Colon
44
Q
  • Retroperitoneal structures
A
  • Pancreas (except tail)
  • Duodenum (2-4)
  • Ascending colon
  • Descending colon