Respiratory system embryo Flashcards
The laryngotracheal groove appears where?
In the floor of the caudal pharynx
Where does the lung bud (respiratory diverticulum) come from?
It comes from an endodermal outgrowth from the foregut off the growing laryngotracheal groove
______ _____ develops, separating the lung bud (ventrally) from the foregut (distally)
Tracheoesophageal septum
The respiratory diverticulum retains a connection with the pharynx at the _____ _____ _____.
Primordial laryngeal inlet
What causes esophageal atresia?
A posteriorly deviating septum
If a tracheoesophogeal fistula occurs and you have acid reflux, where does the acid go?
Instead of coming up the esophagus and to the mouth, the esophagus is connected to the trachea so the acid would go into your windpipe and lungs
In lung buds, what does the endoderm give rise to?
epithelial lining and glands of airways
In lung buds what does the splanchnic mesoderm give rise to?
smooth muscle and CT of airways
The esophagus develops as a portion of the _____ immediately caudal to the ______.
foregut
pharynx
Laryngeal cartilages and musclulature arise from the pharyngeal arch pairs ____ and _____.
4
6
Where does the epiglottis form from?
The mesenchyme of the hypopharyngeal eminence
Laryngeal muscles arising from the 4th arch are innervated by what nerve?
Superior laryngeal nerve
Laryngeal muscles arising from the 6th arch are innervated by what nerve?
Recurrent laryngeal nerve
The lung bud divides to form two ____ ____ ____.
primary bronchial buds
What do primary bronchial buds give rise to?
Primary bronchi
When do the primary bronchial buds form?
Day 28
What gives rise to the visceral pleura of the lungs?
Splanchnic mesoderm
Somatic mesoderm lining the thoracic body wall gives rise to what?
Parietal pleura
The pericardioperitoneal canal becomes what?
The pleural canal
On what day do secondary bronchial buds form?
Day 30
Secondary bronchial buds divide to form what?
Tertiary bronchial buds
Which side has more bronchial buds?
Right side
Trace the path of air as it goes into the lungs.
Trachea primary bronchi secondary (lobar) bronchi tertiary (segmental) bronchi bronchioles terminal bronchioles respiratory bronchioles alveolar ducts terminal sacs (primitive alveoli)
Where is the site of main gas exchange?
Alveoli
When does the pseudo glandular stage occur?
6-16 weeks
When does the canalicular stage occur?
16-26 weeks
When does the terminal sac stage occur?
26 weeks- birth
When does the alveolar stage occur?
32 weeks-8 years old
Will a fetus survive if it is born during the pseudo glandular stage?
No- gas exchange cannot occur because it hasn’t yet developed
When does respiration become possible?
At the end of the canalicular stage- infants born here probably won’t survive
What has happened at the end of the canalicular stage?
Each terminal bronchiole has split into 2 respiratory bronchioles, which have developed primitive alveolar ducts- some lead into terminal sacs, which are primitive alveoli
Through which cells do gasses diffuse?
Type 1 alveolar cells
During the terminal sac stage, more terminal sacs (primitive alveoli) develop and are hugged by capillaries, establishing what?
A blood-air barrier
What do type II alveolar cells do?
Produce, store, and secrete pulmonary surfactant (test question!)
At what point does a baby have enough pulmonary surfactant to survive?
26-28 weeks
What is pulmonary surfactant?
It lines the inner wall of the alveolus and reduces surface tension at the air-alveolar interface to prevent the collapsing of the alveolus upon exhaling. (Test Question!!)
If babies are born at 24-26 weeks, they may survive, but may suffer from what due to insufficient surfactant?
Respiratory distress syndrome
___% of mature alveoli develop postnatally and will continue to develop until _ yeas of age.
95
8
When do alveoli become fully functional?
32 weeks
