Developmental Aspects of Lung Disease Flashcards
What are the stages of lung morphogenesis?
Embryonic - 3-8 weeks Pseudo-glandular - 5-17 Canalicular - 16 - 26 Saccular - 24 - 38 Alveolar - 36 weeks (2 to 3 years)
What happens during the embryonic and pseudoglandular stages of lung development?
Formation of Major Airways Formation of Bronchal tree and portions of respiratory parenchyma
Birth of the acinus
Embryonic: appearance of lung buds and main pulmonary arteries
Pseudoglandular: All conducting airways and accompanying blood vessels form
What is meant by respiratory parenchyma?
Pulmonary parenchyma is a term for lung tissue, including bronchioles, interstitium and alveoli
What happens during the canalicular stage of lung development?
Last generations of the lung periphery formed
Epithelial differentiation - acinai are replacing columnar epithelium with squamous epithelium
Air-blood barrier formed
What is significant about the canaliculi stage?
Life outside of the uterus is possible after the canalicular stage
What happens during the saccular stage?
Expansion of air spaces
Surfactant detectable in amnionic fluid
What happens during the alveolar stage?
Secondary septation
Which stages are organogenesis
Which are differentiation?
Organogenesis (embryonic and pseudoglandular)
Differentiation (cannalicular and saccular)
What types of congenital lung disease exist which arise in the embryonic stage?
Tracheal, laryngeal stenosis (laryngeal stenosis is the narrowing of the airway that may affect the supraglottis, glottis, and/or subglottis)
Pulmonary agenesis (lungs not forming)
Tracheo-oesophageal fistula (abnormal connection between the oesophagus and the trachea)
What congenital lung diseases arise from the pseudoglandular stage of lung development?
Pulmonary sequestration - congenital malformation of the lower respiratory tract. It consists of a nonfunctioning mass of normal lung tissue that lacks normal communication with the tracheobronchial tree, and that receives its arterial blood supply from the systemic circulation.
Cystadenomatoid malformation - one of the lobes containing a group of fluid or air-filled spaces (cysts), rather than lung tissue.
Cyst formation
How long does it take the diaphragm to close?
18 weeks
How is the diaphragm formed?
Various sheets of primitive tissue move towards the centre of the diaphragm.
What are the outcomes of diaphragmatic hernia?
Pulmonary hypoplasia
Persistant pulmonary hypertension
What is meant by diaphragmatic eventration?
Abnormal displacement (i.e. elevation) of part or all of an otherwise intact diaphragm into the chest cavity.
What are the functional changes in the lung at birth?
Change from fluid secretion to fluid absorption
Pulmonary vasodilation
What is Transient tachypnea of the Newborn?
Transient tachypnea of the newborn is a respiratory problem that can be seen in the newborn shortly after delivery. … It consists of a period of rapid breathing (higher than the normal range of 30-60 times per minute). It is likely due to retained lung fluid.
What are the components of surfactant?
Phospholipids and lipophilic components
Stabilises alveoli and promotes gas exchange
When do surfactant proteins appear?
12-14 weeks
What does surfactant deficiency cause?
Hyaline Membrane Disease A syndrome in prematureinfants caused by developmental insufficiency of pulmonary surfactant production and structural immaturity in the lungs. It can also be a consequence of neonatal infection. It can also result from a genetic problem with the production of surfactant associated proteins.
What is chronic neonatal lung disease?
Results from the effects of positive pressure ventilation on a structurally and functionally immature lung
CLD is characterised primarily by prolonged need for ventilatory support, O2 requirements, need for home oxygen and readmission with respiratory illness in the first year of life.
Bronchopulmonary dysplasia is used interchangeably with CLD.
Condition causes eventual lung fibrosis and emphysematous changes
What are the antenatal fetal / paediatric origins of adult lung disease?
In utero nicotine exposure - passes across placenta and reduces airway diameter in the child.
Nutrition
Low birth weight/prematurity (antenatal steroids) – reduces total number of alveoli?
Micronutrients and vitamins
What are the post-natal fetal/paediatric origins of lung disease?
Infection
Growth
Environmental tobacco smoke
Environmental Pollution
Micronutrients/vitamins
Influences on Lung development
Accelerated decline
Early decline
Failure to attain maximal growth
Abnormal decline
What does neonatal lung disease cause?
Increased severity bronchiolitis
“asthma”
? future COPD
What is the treatment for hyaline membrane disease?
Antenatal glucocorticoids
Surfactant replacement
Oxygen
CPAP
Mechanical ventilation
