GI Development Flashcards by Kyro Grace

What is the intraembryonic coelem?

The primordium (organ in earliest stage of development) of the embryonic body cavity.

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What does the intraembryonic coelem give rise to?

PERICARDIAL CAVITY
2 PERICARDIOPERITONEAL CANALS (connect pericardial cavity and peritoneal cavity)
LARGE PERITONEAL CAVITY

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The PARIETAL wall of the of the intraembryonic coelem is derived from what?

SOMATIC MESODERM

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The VISCERAL wall of the of the intraembryonic coelem is derived from what?

SPLANCHNIC MESODERM

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What do the “limbs” represent on the intraembryonic coelom?

The DISTAL part of each limb of the intraembryonic coelom is continuous with what?

Limbs of the intraembryonic coelom represent the future pleural and peritoneal cavities.

EXTRAEMBRYONIC COELEM

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Where does midgut of the hernia go through?

It will go through the communication spot between the intra and extra embryonic coelom.

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Where does pericardial cavity open into ?

Opens into the right and left pericardioperitoneal canals.

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What is the septum transversum?
Where does the septum transversum sit?

It is a thick plate of mesoderm
It sits in between the thoracic cavity and the vitelline duct.

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What does the septum transversum eventually become?

CENTRAL TENDON OF THE DIAPHRAGM

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What happens in the 5th week at the junction between the unpaired pericardial cavity and the 2 pericardioperitoneal canals?

What vein and nerves do they contain?

They start growing towards each other. (form a triangle almost)

They contain the COMMON CARDINAL VEIN (the trunk of it) and the PHRENIC NERVES

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How do the pleural cavities form?

Pleural cavities form as a result of the lung buds growing into the pericardioperitoneal canals

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When do the pleural cavities (house the lungs) officially become SEPARATED?
Where does the separation of the PLEURAL CAVITIES take place?

Once the pleuropericardial membranes have fused with the mesenchyme
At THE ROOT OF THE LUNGS.

There is a right and left pleuropericardial membranes

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What gives rise to the future FIBROUS PERICARDIUM?

Right and Left pleuropericardial membranes. (2 of them)

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After separation of the pleural cavities, how is the pleural cavity connected (temp) to the peritoneal cavity?

Through the PERICADRIOPERITONEAL CANALS

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Where is the peritoneal cavity connected to the extraembryonic coelom?

At the umbilicus

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What are the 4 embryonic structures that help develop the DIAPHRAGM?

Septum Transversum
2 Pleuroperitoneal membranes
Dorsal mesentery of the esophagus
Muscular components of the 3rd-5th cervical somites

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What part of the diaphragm does the septum transversum help form?

CENTRAL TENDON OF THE DIAPHRAGM

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What part of the diaphragm does the 2 pleuroperitoneal membranes help form?

EARLY DIAPHRAGM

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What forms the median portion of the diaphragm?

DORSAL MESENTERY OF THE ESOPHAGUS

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What does the crura of the diaphragm develop from?

Myoblasts the grow into the dorsal mesentery of the esophagus

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What forms the muscular part of the diaphragm?

Muscular components of the 3rd-5th cervical somites

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What is the most common cause of pulmonary HYPOplasia (incomplete development of lungs)?
(portions of GI tract literally go into the thoracic cavity).

CONGENITAL DIAPHRAGMATIC HERNIA (CDH)

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What is congenital diaphragmatic hernia (CDH)?

It is posterolateral defect caused by the failure of 1 or both of the pleuroperitoneal membranes (usually the left one).
It is common (1 in 2200 newborns)

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What 2 membranes close the primordial gut?

OROPHARYNGEAL MEMBRANE (cranial end)
CLOACAL MEMBRANE (caudal end)

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What are the epithelium at both the cranial and caudal end of the GI tract called? (Derived from ectoderm)

STOMEDEUM (cranial end) PROCTODEUM (caudal end)

What is the primordial gut divided into? (4 parts)

Pharynx Foregut Midgut Hindgut

What are the derivates of the foregut? How do they receive blood?

Lower respiratory system, esophagus, stomach, first 2 parts of dueodenum, liver, pancreas, biliary apparatus (hepatic ducts, bile duct, gallbladder) Celiac trunk delivers blood (except for the pharynx, resp. tract, and upper 2/3rd of esophagus)

What does the respiratory diverticulum elongate into?

Laryngotracheal tube (this tube initially opens into the foregut)

Where does the respiratory diverticulum develop?

It is a protrusion on the ventral (top) part of the foregut.

What separates the laryngotracheal tube from the foregut?

Tracheoesophageal septum

What can result when there is abnormal separtion/partioning of the esophagus and trachea at the tracheoesophageal septum?

Esophageal atresia Either with or without tracheoesophageal fistulas (TEFs) - abnormal pairing between trachea and esophagus

Describe the most frequent TEF (tracheoesophageal fistula)

Upper esophagus ends in a blind pouch and the lower segment of the esophagus forms a fistula with the trachea (abnormal pairing between lower part of esophagus and trachea)

What appears as a result of the foregut dilating?

STOMACH

Differntial growth of the foregut causes what to form initially on the future stomach?

GREATER CURVATURE

Because the stomach rotates 90 degrees clockwise, what happens to the vagus nerves ? (Hint: Left and right vagus nerve become what as they descend) ?

Left vagus nerve becomes the anterior vagal trunk Right vagus nerve becomes the posterior vagal trunk

What does the DORSAL MESENTERY develop into? (3 things)

ROOT of THE MESENTERY (leads to THE MESENTERY) TRANSVERSE MESOCOLON SIGMOID MESOCOLON

What does the dorsal mesogastrium form?

GREATER OMENTUM

What is the space posterior to the stomach called?

Lesser Sac

What is the space posterior to the stomach called?

Lesser Sac

What does the VENTRAL MESOGASTRIUM eventually form?

LESSER OMENTUM FALCIFORM LIGAMENT

Where does the duodenum's blood supply come from?

CELIAC TRUNK and little bit from superior mesenteric artery

What part of the duodenum are considered foregut ?

1st and 2nd portions (SUPERIOR and DESCENDING portions of duodenum)

What parts of the duodenum are considered midgut?

3rd and 4th portions of duodenum (HORIZONTAL and ASCENDING portions of duodenum)

What access do the duodenum and pancreas rotate on causing them to rest against the posterior abdominal wall and making the 2nd-4th portion of duodenum and pancreas retroperitoneal ?

Pancrease and duodenum rotate on a LONGITUDINAL AXIS

What are the 2 common types of CONGENITAL INTESTINAL OBSTRUCTION?

DUODENAL STENOSIS DUODENAL ATRESIA

Where is DUODENAL STENOSIS most commonly found?

3rd and 4th portion of duodenum (HORIZONTAL and ASCENDING portion)

Where is DUODENAL ATRESIA most commonly found?

2nd and 3rd portion of duodenum (DESCENDING and HORIZONTAL portion)

What is the another name of liver bud (its an outgrowth of endodermal epithelium at the distal end of foregut) ?

HEPATIC DIVERTICULUM

Where does the liver bud develop?

Liver bud develops between the layers of ventral mesogastrium

What forms the COMMON BILE DUCT?

NARROWING of the connection between liver bud and foregut

What forms the hepatic (liver) cords?

The cranial portion of the liver bud

What forms the hepatocytes?

The hepatic (liver) cords

Small ventral outgrowth from the COMMON bile duct form what?

GALLBLADDER CYSTIC DUCT

Are accessory hepatic ducts and gallbladder duplication symptomatic or asymptomatic?

ASYMPTOMATIC

What is EXTRAHEPATIC BILIARY DUCT ATRESIA? For 15-20% of these patients who have a patent proximal duct, what can be done so they can survive?

hepatic ducts fail to recanalize LIVER TRANSPLANT

What can cause intrahepatic biliary duct atresia?

FETAL INFECTIONS (can be fatal, but usually stays benign for awhile)

From the duodenal endoderm, what 2 things form as outgrowths?

DORSAL PANCREATIC BUDS VENTRAL PANCREATIC BUDS

What 3 structures will the dorsal pancreatic bud help form?

TAIL, BODY, HEAD of pancreas (superior part of head)

What structures do the ventral pancreatic bud help form?

UNCINATE PROCESS of pancreas HEAD (Inferior portion) of pancreas

What 2 structures help form the main pancreatic duct?

DISTAL part of DORSAL PANCREATIC DUCT + ENTIRE VENTRAL PANCREATIC DUCT

What 2 structures help form the ACCESSORY PANCREATIC DUCT?

Proximal part of DORSAL PANCREATIC DUCT

When do Pancreatic Islets (of Langerhans) develop?

3rd month of fetal life

When does Insulin secretion begin?

BETWEEN 10th week and 5th month of fetal life

How does an annular pancreas form? Remember --> annular pancreas forms when there is a duodenal stenosis.

It forms by the ventral pancreatic bud splitting off (bifid) and wrapping around the duodenum forcing a constriction. (most common birth defect in the pancreas)

What is the splenic bud derived from?

MESODERMAL CELLS

What ligament attaches the splenic bud to the dorsal wall?

SPLENORENAL LIGAMENT

What ligament attaches the splenic bud to the stomach?

GASTROSPLENIC LIGAMENT

Is the spleen part of the foregut?

HELL NAHH

When the midgut loop (primary intestinal loop) starts to project into the proximal part of the umbilical cord, what is it called?

PHYSIOLOGIC UMBILICAL HERNIATION

How does the midgut loop communicate with umbilical vesicle?

Through the omphaloenteric duct (vitelline duct)

How does the midgut loop? (clockwise or counterclockwise, what degree)

MIDGUT LOOPS 90 DEGREES COUNTERCLOCKWISE

When the abdominal cavity enlarges during the 10th week, what happens to physiologic umbilical herniation?

It reduces

How does the large intestine loop? (After it has looped 90 degrees counterclockwise)

180 Degrees counterclockwise (so total is 270 degrees counterclockwise)

What is the appendix initially (during 6th week of fetal life)?

Appendix is initially a small diverticulum (pouch) of the cecum.

What appears as a swelling of the caudal limb of the midgut loop?

EARLY CECUM and APPENDIX (appear during the 6th week)

What is gastroschisis? What drug is causing increased cases of it?

Bowel loop herniates through the abdominal wall WITHOUT A SAC (may be associated with umbilical vein rupture) Cocaine use

What is omphalocele?

Persistant herniation of bowel is enclosed within the amniotic sac around the base of the umbilical cord 25% mortality rate Usually occurs with other defects (cardiac defects or neural tube defects)

What is ILEAL (Meckel) DIVERTICULUM? If it becomes inflamed, what disease symptoms can it mimic?

A persistent vitelline duct remnant (3-5x more prevelant in boys) appendicitis-like symptoms

What attaches the ileal diverticulum to the umbilicus? (Hint: a fibrous cord)

OMPHALOENTERIC FISTULA

What are the different abnormal midgut rotations that can occur?

NONROTATION (midgut doesn't rotate at all) MIXED ROTATION and Volvulus (small intestine twists) REVERSED ROTATION (now sma compresses the transverse colon) SUBHEPATIC CECUM and APPENDIX (cecum and appendix are higher up and right underneath the liver) INTERNAL HERNIA (hernia comes up into the midgut MIDGUT VOLVULUS (twisting of large intestine)