Developmental aspects of lung disease Flashcards
What are the phases of lung morphogenesis?
Embryonic 3-8 weeks Pseudoglandular 5-17 weeks Canalicular 16-26 weeks Saccular 24-38 weeks Alveolar 38 weeks-2/3 years
What happens in the pseudoglandular phase of lung development (5-17 weeks)?
Start to get cartilage formation
Gas exchange not possible
What happens in the canalicular phase of lung development (16-26 weeks)?
Start to get squamous epithelium and blood vessels beside airways
Gas exchange just possible
What happens in the saccular phase of lung development (24-38 weeks)?
Acini increase
Surfactant production
What happens in the alveolar stage of lung development?
Acini bud off to form alveoli
How many alveoli are present at birth compared to 3-8 years?
100-150 million
200-600 million
What happens after alveoli stop developing in number?
Develop in size
What can problems in the embryonic period of lung development cause?
Tracheal/laryngeal stenosis
Pulmonary genesis
Tracheo-oesophageal fistula
What can problems in the pseudoglandular phase of development cause?
Pulmonary sequestration
Cystadenomatoid malformation (formation of multiple cysts)
Cyst formation
How does the diaphragm develop?
Forms in different parts then connects
Mainly muscular tissue but contains fibrous tissue
When does the diaphragm close?
About 18 weeks
What are some possible diaphragmatic abnormalities?
Diaphragmatic hernia
Eventration (protrusion)
What does a diaphragmatic hernia cause?
Pulmonary hypoplasia
Persistent pulmonary hypotension
What are the functional changes of the lungs at birth?
Fluid secretion–> fluid absorption
Pulmonary vasodilation
What does fluid i the lungs after birth cause?
Transient tachypnoea of the newborn
Normally resolves after 24-48 hours
What is surfactant?
Detergent like substance that decreases the work of breathing
Stabilises alveoli and presents them from collapsing
Promotes gas exchange
What is surfactant produced by?
Type 2 pneumocytes
When does surfactant production begin?
About 20 weeks gestation
What is neonatal respiratory distress syndrome?
Surfactant deficiency causing difficulties breathing
What is the treatment for neonatal respiratory distress syndrome?
Antenatal glucocorticoids Surfactant replacement Oxygen CPAP Mechanical ventilation
What are the antenatal origins of adult lung disease?
In utero nicotine exposure
Nutrition
Low birth weight/prematurity
Micronutrients/vitamins
What are the post natal origins of adult lung disease?
Infection
Growth
Environmental tobacco smoke or pollution
Micronutrients/vitamins
