At what weeks of gestation does the embryonic lung development phase span?
3 - 8 weeks
What happens first during the embryonic phase?
Lung offshoots off the foregut
What germ layer does the lung grow into?
What does the primary bronchial tube act as at this point?
What does the bronchial tube gland secrete into?
At this point, how close do blood vessels lie to airways?
What stage follows the embryonic stage and how long does it last?
- Pseudo glandular - 5 - 17 weeks
What starts to form at the pseudo glandular phase?
- Very early lung
- Lobes become obvious
What starts to form in the bronchioles during the pseudoglandular phase?
How much metabolic activity occurs during the pseudoglandular phase?
Describe the image relating to A) blood vessel position B) glandular aspect C) myofibrils
A) still far away from airways
B) acinar tubules widely branching
C) myofibrils forming around bronchioles
What is the next phase in lung development following the pseudoglandular and how long does it last?
- 16 - 26 weeks
What is the main formation during the canalicular phase?
- Squamous epithelium forms
What does the formation of the squamous epithelium during the canalicular phase allow?
Gas exchange to be possible
What else occurs during the canalicular phase to allow gas exchange to occur?
Blood vessels move closer to the saccules
What phase follows the canalicular phase and how long does it last?
- 24 - 38 weeks
What occurs during the saccular phase?
More saccules form
What phase begins at 36 weeks and can last 2/3 years after birth?
What happens to the saccules during the alveolar phase?
They turn into alveoli
What fills the alveoli during gestation?
What is the name given to the separation of alveoli into segments?
How many alveoli does the average human start life with?
100 - 150 million
How many alveoli does the average human have after septation?
200 - 600 million
STUDY THE FOLLOWING DIAGRAM
When does surfactant begin to form?
Around 24 weeks
STUDY THE FOLLOWING DIAGRAM
What is tracheal/laryngeal stenosis?
Abnormal narrowing of the main airways
What is pulmonary agenesis?
Failure of lung development during the embryonic stage
What is tracheo-oesophageal fistula?
Where the oesophagus infringes onto the trachea and they join together
What is pulmonary sequestration?
When their is a functioning mass of normal lung tissue that has no link to the main airways
What is cystadenamatoid malformation?
Areas of the lung that are solid or fluid filled masses that can have an effect on breathing
What does congenital mean?
Present at birth
What does the diaphragm start off as in development?
Tissue that fuses with the abdominal wall
When does closure of the diaphragm occur?
What can cause a diaphragmatic hernia during development?
Pulmonary hypoplasia - the diaphragm will infinge into the space where the lung should be
What does eventration mean with reference to the diaphragm?
Some areas are more dense than others
What functional change occurs during the first few breaths of life?
The lungs change from fluid secretion to fluid absorption to get rid of the fluid filling the airways
What can result if the functionality of the lung is unable to change to fluid absorption?
Wet lung - acute respiratory distress
What happens to the blood vessels around the alveoli during the first few breaths
What does surfactant act as?
When do type 2 pneumocytes appear during development?
12 - 14 weeks
What is the name of the disease given to a surfactant deficiency?
Hyaline Membrane Disease
How is hyaline membrane disease treated?
- Antenatal glucorticoids
- Surfactant replacement
- High conc. oxygen
- Mechanical ventilation
What are 2 examples of chronic neonatal lung diseases?
- Bronchopulmonary dysplasia
- Chronic lung disease of prematurity
What are the antenatal origins of adult lung disease?
- In utero exposure to nicotine
How does smoking affect FEV?
If someone is born with poor lung function, what does it increase the risk of developing later in life?