1.1.2 Development of the Respiratory System Flashcards
Respiratory diverticulum or lung bud is an outgrowth of what?
The endodermal tube
Epithelium of the respiratory system is derived from what germ layer?
Endoderm
Cartilaginous, muscular and connective tissue components of the trachea and lung are derived from?
Splanchnic mesoderm
What does the traschoesophageal septum form from?
The tracheoesophageal ridges
Tracheoesophageal ridges fuse together to form the tracheoesophageal septum. It is the tracheoseophageal septum that is responsible for separating the tracheal primordium from the esophageal primordium.
Pseudostratified ciliated with goblet cells, endoderm
How many lung buds does the right lung have? Left?
3 for the right
2 for the left
What are the pericardioperitoneal canals?
The narrow spaces that are gradually filled by the expanding lung buds.
What separates the pericardioperitoneal canals from the peritoneal and pericardial cavities?
pleuroperitoneal and pleuropericardial folds
What germ layer forms the visceral and parietal pleura?
Mesoderm
Once the pericardioperitoneal canals separate from the pericardial and peritoneal cavities what occurs?
The lungs will begin to expand into the pleural cavities
During the 5th week, pleuropericardial folds grow out from the lateral body wall toward the midline. What are the next steps following this?
They fuse with each other and with mesoderm associated with the esophagus. Simultaneously, the roots of these folds migrate ventrally so that they ultimately originate from the ventral body wall.
What is the role of the pleuropericardial folds?
The pleuropericardial folds with their associated serous membrane form the pericardial sac and transform the primitive pericardial cavity into a definitive pericardial cavity and right and left pleural cavities.
Explain the relationship between the septum transversum and the pericardioperitoneal canals.
In the future thoracic region, the septum transversum forms a ventral partition beneath the paired pericardioperitoneal canals (arrows), which interconnect the primitive pericardial cavity cranially and peritoneal cavities caudally.
Explain how the separation of the abdominal and thoracic cavities occurs. (Think diaphragm formation).
Closure of the pericardioperitoneal canals. Between weeks 5 and 7, a pair of horizontal pleuroperitoneal membranes grow from the posterior body wall to meet the septum transversum (arrows) A, thus closing the pericardioperitoneal canals. These membranes form the posterior portions of the diaphragm and completely seal off the pleural cavities from the peritoneal cavity. Arrows in B indicate invasion of the developing diaphram by muscle fibers from the adjacent body wall.
What components make up the diaphragm?
The definitive diaphragm is a composite structure including elements of the septum transversum, pleuroperitoneal membranes, and esophageal mesenchyme, as well as a rim of body wall mesoderm.
What is a diaphragmatic hernia?
A hole in the diaphragm leads to parts of the intestine being in the chest cavity. This can cause pulmonary hypoplasia and pulmonary insufficieny.
What is correct about the previously described congenital anomaly?
- it is found on the right side
- frequently associated with hyperplastic lungs
- best diagnosed on physical exam of the mother
- frequently asymptomatic at birth
- frequently presents with a scaphoid abdomen
- frequently presents with a scaphoid abdomen
How do patients with diaphragmatic hernia respond to bag-mask ventilation?
They tend to get worse
Where do 90% of diaphragmatic hernias occur?
They occur on the left side
Why can bag-mask ventilation make neonates with diaphragmatic hernia worse?
This causes the stomach and bowel to fill with gas which will further compromise respiration and cardiac action