Embryology Flashcards
What are the five stages of lung development?
“Every pulmonologist can see alveoli”
1. Embryonic
2. Pseudoglandular
3. Canalicular
4. Saccular
5. Alveolar
The respiratory epithelium that lines the airways is derived from the _
The respiratory epithelium that lines the airways is derived from the endoderm
The cartilage, muscle, and lung tissue found in the RT is all derived from the _
The cartilage, muscle, and lung tissue found in the RT is all derived from the mesoderm
As early as 26 days after fertilization, the increase in _ acid causes the formation of the _ (early lung structure)
As early as 26 days after fertilization, the increase in retinoic acid causes the formation of the lung bud
The lung bud branches off the anterior aspect of the developing _
The lung bud branches off the anterior aspect of the developing foregut
* This portion of the foregut will later become the esophagus
At first, the lung bud is open to the foregut; but eventually the _ will form to separate the two tubes: the trachea and the esophagus
At first, the lung bud is open to the foregut; but eventually the tracheoesophageal septum will form to separate the two tubes: the trachea and the esophagus
The formation of the tracheoesophageal septum is vital; abnormal septation can result in _ or _
The formation of the tracheoesophageal septum is vital; abnormal septation can result in esophageal atresia or tracheoesophageal fistula
The embryonic stage lasts from week _ to _ and involves the development of _ –> _ –> _
The embryonic stage lasts from week 4-7 and involves the development of lung bud –> bronchial buds –> pulmonary vasculature
The pseudoglandular stage is marked by extensive _ which is signaled by _
The pseudoglandular stage is marked by extensive branching of airways and blood vessels which is signaled by fibroblast growth factors
Respiratory bronchioles become prominent in the _ stage of development
Respiratory bronchioles become prominent in the canalicular stage of development
* Rudimentary acini also form (respiratory bronchiole + alveolar duct and sac)
* Capillaries become more extensive
Pseudoglandular stage of gestation lasts from weeks _ to _
Pseudoglandular stage of gestation lasts from weeks 5-17
The canalicular stage of gestation lasts from weeks _ to _
The canalicular stage of gestation lasts from weeks 16-25
The saccular stage lasts from weeks _ to _
The saccular stage lasts from weeks 24- birth
What changes occur during the saccular stage?
During the saccular stage, many more terminal sacs develop
* Epithelium becomes very thin
* Septation begins to divide the alevolar sacs into small units
* Type I and II pneumocytes become more prominent
Alveolar stage lasts from weeks _ to _
Alveolar stage lasts from weeks 32- birth
* Alveolarization occurs as we have more acini and greater vascularization
At birth only about _ percent of alveoli are mature, the remaining _ mature after birth
At birth only about 5% of alveoli are mature, the remaining 95% mature after birth
* Lung maturation continues until age 8
Inspiration-like movements begin early in utero; aspiration of _ helps to stimulate lung development
Inspiration-like movements begin early in utero; aspiration of amniotic fluid helps to stimulate lung development
* When babies are born their first breath triggers rapid resorption of amniotic fluid into the alveolar capillaries and lymphatic system
Esophageal atresia and tracheoesophageal fistulas prevent the fetus from swallowing amniotic fluid in utero, therefore most of them are detected prenatally due to _
Esophageal atresia and tracheoesophageal fistulas prevent the fetus from swallowing amniotic fluid in utero, therefore most of them are detected prenatally due to polyhydramnios
* Signs after birth: coughing, choking, drooling, cyanosis
Pulmonary hypoplasia can be a primary genetic condition or it can be secondary to insufficient amniotic fluid called _
Pulmonary hypoplasia can be a primary genetic condition or it can be secondary to insufficient amniotic fluid called oligohydramnios
* Other causes include diaphragmatic hernia, abnormal diaphragmatic activity
_ is a developmental defect in the diaphragm that allows abdominal contents to protrude up into the thoracic cavity and is a “can’t miss” cause of NRDS after birth
Congenital Diaphragmatic Hernia is a developmental defect in the diaphragm that allows abdominal contents to protrude up into the thoracic cavity and is a “can’t miss” cause of NRDS after birth
Signs of NRDS
Classic presentation of NRDS is a neonate showing respiratory distress
* Tachypnea (more than 60 breaths per minute)
* Subcostal and intercostal retractions
* Nasal flaring
* Cyanosis
* Expiratory grunting
The most common reason for respiratory distress in newborns is _ which is failure to clear alveolar fluid from the lungs
The most common reason for respiratory distress in newborns is transient tachypnea which is failure to clear alveolar fluid from the lungs
* Chest x-ray shows over inflated lungs, interstitial edema, small pleural effusions
In neonates with NRDS the chest x-ray will show _
In neonates with NRDS the chest x-ray will show ground-glass infiltrates in all lung fields
* Ground glass = diffuse, fine reticulonodular infiltrates
NRDS can be prevented in utero by administering _ to the mother 2-7 days before delivery
NRDS can be prevented in utero by administering corticosteroid to the mother 2-7 days before delivery
