Development of Respiratory System Flashcards
What develops in the ectoderm?
Neural groove
What are the tips of the neural groove called?
Neural crest
What happens when the neural groove is developing?
The lateral plate mesoderm will divide into the parietal and visceral mesoderm which becomes the serious membranes
What does the parietal layer form?
Body walls
What does the visceral layer form?
Surround the organs
What does the parietal layer do in relation to the ectoderm?
Starts to merge
What two things occur when the parietal layer merges with the ectoderm?
Primitive yolk sac becomes pinched and this will develop into the digestive tract. The visceral layer of the lateral plate mesoderm will envelope the future gut tube
The leading edge of the ectoderm and the parietal layer of the lateral plate mesoderm will move antero-medially
What does the eventual connection between the gut tube and secondary yolk form?
Vitelline duct
What structures are present once the parietal layer fully fuses with the lateral plate mesoderm?
A cavity (coelom) which will become the thoracic, abdominal and pelvic cavity
A body wall made out of a surface ectoderm and parietal layer of lateral plate mesoderm deep to it
The gut tube, suspended by visceral layer of lateral plate mesoderm
Pericardio-peritoneal canals
Lecture
What happens when the embryo is about 4 weeks old?
In the cervical portion of the gut tube, in the ventral midline, the respiratory diverticulum starts to appear
The respiratory diverticulum expands ventrally and towards the chest, in front of the gut tube
Tracheo-oesophageal ridged grow towards each other and separate the RD from the gut tube
The diverticulum bifurcates into two branches
Terminal ends of these dilations are called lung buds
When do the pharyngeal arches begin to develop?
Week 4-5
What separates the pharyngeal arches?
Pharyngeal clefts
How many pharyngeal arches are there?
5
What does each pharyngeal arch have?
Cartilaginous element
An aortic arch
Cranial nerve
Where is the gut tube and RD still connected?
Laryngeal orifice
What will the upper end of the respiratory diverticulum form?
Larynx
What does the middle section of respiratory diverticulum form?
Trachea
What will the lower end of the respiratory diverticulum form?
Tertiary bronchi
Bronchioles
Alveoli
What does the respiratory diverticulum develop from?
Endoderm and surrounded by the visceral layer of the lateral plate mesoderm
What is the only part of the respiratory system that is derived from the endoderm?
Epithelium
What structures of the respiratory system are derived from mesoderm?
Cartilage
Trachealis muscle
What does the bronchial tree do when it grows?
Pushes the visceral layer of lateral plate mesoderm
What stages do the lungs develop in?
Pseudoglandular
Canalicular
Terminal saccular
Alveolar
What stages in lung development are incompatible with gas exchange?
Pseudoglandular
Canalicular
What are the four sources of diaphragm origin?
Pleura-peritoneal folds
Septum transversum
Mesentery of the oesophagus
Muscular in-growth from the body wall
What forms the central tendon of the diaphragm?
Septum transversum
What does the septum transversum contain?
Myoblasts from somites C3,4,5
What does failure in normal development of any sources of the diaphragm lead to?
Diaphragmatic hernia
What occurs 90% of the time in babies with congenital anomalies of the trachea?
Tracheo-oesophageal fistula
Communication between the trachea and oesophagus
Accompanied by oesophageal atresia
What happens if the trachea-oesophageal fistula allows passage from the oesophagus into the trachea?
When feeding, milk will enter and cause chocking possible development of pneumonitis and pneumonia
Also possible of retrograde passage of gastric acid
What is oesophageal atresia?
When the two ends of the oesophagus don’t meet, stopping the transport of food
What is a diaphragmatic hernia?
When the diaphragm fails to close during prenatal development, and the contents from the abdomen (stomach, intestines and/or liver) migrate into the chest through this hole
What is respiraotyr distress syndrome?
Insufficient surfactant results in the collapse of the alveolar wall during expiration
Deficiency of surfactant secretion results in respiratory distress syndrome
How we treat respiratory distress syndrome?
Glucocorticoids
At what level does the trachea-oesophageal ridge form on the gut tube?
Foregut
What are the different pharyngeal arches?
1st
2nd
3rd
4th
6th
What are the two swellings found on the anterior walls of the pharyngeal arches?
Laryngeal swellings
Epiglottal swelling
Where does septum transversum grow from?
Anteriorly
Where does the pleuroperitoneal fold grow from?
Posteriorly
What is a fistula?
When part of the oesophagus either attaches or opens up into the trachea
What are the different types of hernias?
Bochdalek hernia
Morgagni hernia
Central hernia
What causes a Bochdalex hernia?
Posterolateral defect in fusion of pleura-peritoneal folds
What causes a Morgagni hernia?
Failure in the development in septum transversum
What causes a central hernia?
Defect on central tendon
What hernia is most common?
Bochdalek hernia
