Pulmonary development Flashcards
Two layers of pulmonary pleura
Parietal and visceral with a thin film of fluid in between
How many lobes are in the lungs
left: superior and inferior. Right: superior, middle, inferior
What supplies the lungs? What drains the lungs?
pulmonary arteries, bronchial arteries, bronchi supply lungs. Pulmonary veins and lymphatics drain the acini (gas exchange unit)
List the progression of the airway structures
trachea > bronchi > bronchioles > terminal bronchioles >respiratory bronchioles > alveolar ducts > alveolar sacs
Which parts of the airway are gas exchange regions
•Respiratory bronchiole, alveolar ducts and alveoli
Which parts of the airway are conducting airway regions
trachea, bronchi, bronchioles
Layers of the airway walls
Inner mucosal surface (epithelial cells, cilia, and goblet cells), the smooth muscle layer, and the outer connective tissue layer. Cartilage is present in the trachea and bronchi.
Describe 2 types of cells in the gas exchange regions
squamous lining cells (type I cells or pneumocytes) and secretory cells (Type II cells). Type I cells comprise 95% of alveolar surface area and fuse with capillary endothelium to create a thin membrame for gas transfer. Type II cells 1) repair or replace injured Type I pneumocytes, and 2) secrete surfactant, a substance which lowers alveolar surface tension.
Lungs develop from what embryological structure?
lung bud of the gut tube endoderm- an outpouching btw the 4th and 6th brachial arches
Pulmonary circulation develops from what embryological structure?
Mesenchyme surrounding the lung bud
What are the stages of development of the lungs
Embryonic, pseudoglandular, canalicular, saccular, alveolar
Embryonic stage details
26 days to 6 weeks: Foregut endoderm extends into surrounding mesenchyme. 3 rounds of branching establish lung lobes. Branching is initially asymmetric
During lung branching, what occurs at branch points and developing buds
–At branch points epithelial cell division stopped and collagen produced. At developing buds growth factors produced to induce epithelial mitosis
pseudoglandular stage details
6 to 16 weeks: 14 rounds of branching form terminal bronchioles. Cartilage, smooth muscle cells and mucus glands develop from splanchnic mesenchyme
canalicular stage details
16 to 28 weeks: Terminal bronchiole divides into 2+ respiratory bronchioles, Surfactant production begins and increases as weeks progress. Initial development of pulmonary capillary bed and fetal “breathing” is detected
16 to 28 weeks: Terminal bronchiole divides into 2+ respiratory bronchioles, Surfactant production begins and increases as weeks progress. Initial development of pulmonary capillary bed and fetal “breathing” is detected