F - Embryo of the Respiratory System - Cole Flashcards
(32 cards)
Early lung development regulated by
Location - TBX4 (from T-box transcription factor gene family)
Increased RA
Development of lungs being?
Week 4
With formation of laryngeotracheal (respiratory) diverticulum
What is the cause of tracheoesophageal fistula
Abnormal communication between trachea and esophagus
Improper formation of tracheoesophageal septum
What does a chest X-ray of a tracheoesophageal fistula look like?
An air-filled pouch representing the proximal esophagus.
Distension of this proximal esophagus causing anterior displacement of the trachea
Misexpression of Tbx4 causes what two things?
Ectopic endodermal budding and tracheo-esophageal fistula
Symptoms of tracheoesophageal fistula?
Excessive salivation with choking, coughing and sneezing
When fed, swallow normally but begin to cough and struggle as fluid returns through nose and mouth
2 other types of abnormalities
Laryngotracheoesophageal clefts and tracheal stenosis
Development of bronchi
Week 5 - divide into 2 bronchial buds that will become primary bronchi
What week do the lobes of lungs development?
External aspect - week 6
Advanced stage - end of week 6
What does the splanchnic mesoderm differentiate into?
Smooth muscle, nerves and blood vessels of the lungs
The bronchioles are modeled to optimize what?
Max surface area for gas exchange
To minimize resistance to airflow
–max area with minimum resistance
Describe the embryonic stage of lung development
Weeks 4-7
Lungs grow into pleural cavities
Differentiation of pleura
Describe (Pseudo)Glandular Stage
Weeks 8-16
NO respiratory components, gas exchange
Resemble a gland
Induction of vasculogenesis of pulmonary veins mediated by VEGF
What mediates the induction of vasuclogenesis of pulmonary veins?
VEGF
Describe the Canalicular stage of lung development
Weeks 17-26
Formation of primitive alveoli
Capillaries in walls
Type I cells form part of what?
The blood-air barrier
Type II cells job?
Secretory cells produce surfactant
Reduces surface tension
Facilitates alveolar expansion
How much alveoli is formed after birth?
90%
-primary mechanism is septation of pre-existing alveoli
During what lung development phase is the fetus viable?
Canalicular phase
Misexpression of Fgf10 causes
Ectopic endodermal budding, tracheo-esophageal fistula and ectopic Tbx4 expression
Characteristics of infant respiratory distress syndrome
Primarily in immature lung
60% in < 28 weeks gestation
5% in > 37 weeks gestation
Labored breathing, def or absence of surfactant
Histo - alveoli are collapsed, RBCs accumulate
Atelectasis
The incomplete expansion or collapse of parts of or a whole lung
Hyaline membrane disease
Alveoli filled with debris in uniform distribution
Looks like ground glass on chest x-ray
Congenital neonatal emphysema
Misnomer - NO alveolar destruction
Over-distension of one or more lobes of lung
Caused by collapsed bronchi, bronchial cartilage doesn’t develop
