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
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
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
4
Q
- What anatomial structure helps to separate the foregut and the midgut?
A
- Major duodenal papilla
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.
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.
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)
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
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
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))
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
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
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
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
15
Q
- Spleen is made from what germ layer
- It is hematopoetic from weeks _ to _
A
- Mesoderm
- 9-28
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)
17
Q
- Omphalocele
A
- Failure of bowel to return to body cavity
- Occurs during WK 10
- NOT AN UMBILICAL HERNIA

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
- Hollow gut tube
- Endothelial lining proliferates
- Recanalization
- 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
* **Omphalomesenteric fistula**
* Vitellointestinal duct remains open
* Feces coming out of umbilicus

26
* **Omphalomesenteric cyst**
* Usually detected post-mortum
* Cyst develops in vitelline duct

27
* **Omphalomesenteric ligament**
* **Fibrous band connecting ileum to umbilicus but didn't pull enough on ileum to cause a diverticulum**

28
* 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 \_
* Ectoderm and endoderm
* Urorectal
* Mesoderm, endoderm and ectoderm
29
* The urorectal septum comes from the \_
* Perineal body
30
* **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?**
* 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
* Anorectal malformations

32
* What are the three body cavities?
* Pericardial
* Pleural (2)
* Peritoneal
33
* Formation of the pleural-peritoneal membrane occurs when pleuro-peritoneal membranes fuse with the \_
* What germ layer is this made from?
* Septum transversum
* Somatic layer of the lateral plate mesoderm
34
* The septum transversum forms the _ of the diaprhagm
* The dorsal mesentary of the esophagus is also known as the \_
* Central tendon
* Crura
35
* 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**
* **Serous membrane/splanchnic mesoderm**
* Dorsal
* Ventral
* Splanchnic
* Somatic

36
* Regional specializations of the mesentaries
* Thoracic esophagus and anus are \_
* Foregut and heart
* Abdominal Cavity and Liver
* Midgut and Hindgut
* Retroperitoneal

37
* **What makes up the dorsal mesogastrium?**
* **Splenorenal (leinorenal ligament)**
* **Gastrolienal ligament**
* **Greater omentum**
## Footnote
**Attaches posterior body wall to stomach**
38
* **What makes up the ventral mesogastrium?**
* Lesser omentum
39
* **What makes up the ventral mesentary?**
* Falciform ligament (liver to anterior abdominal wall)
40
* **The greater omentum comes from _ mesogastrium and has _ layers**
* Dorsal
* 4
41
* **Fusion of mesentaries with body walls results in _ structures**
* Secondary retroperitoneal
42
* What are some examples of secondary retroperitoneal structures?
* Mesogastrium dorsal to spleen
* Mesoduodenum
* Ascending mesocolon
* Descending mesocolon
43
* Intraperitoneal structures
* Stomach
* Tail of pancreas
* First part of duodenum
* Jejunum, Ileum
* Transverse Colon
* Sigmoid Colon
44
* Retroperitoneal structures
* Pancreas (except tail)
* Duodenum (2-4)
* Ascending colon
* Descending colon