Anatomy Flashcards
(39 cards)
What are the two zones of the lung?
Conducting zone and respiratory zone
What is the purpose of the conducting zone of the lung?
Warms, humidifies and filters air but does not participate in gas exchange –> anatomic dead space
What are the structures in the conducting zone?
Large airways: Nose, pharynx, laryxn, trachea, bronchi
Small airways: bronchioles, terminal bronchioles
Where is the least airway resistance?
Terminal bronchioles; large numbers in parallel.
To what level does cartilage extend?
Bronchi
To what level do goblet cells extend?
Bronchi
To what level do psuedstratified ciliated columnar cells extend?
To beginning of terminal bronchioles, then transition to cuboidal
To what level does airway smooth muscle extend?
To end of terminal bronchioles
What defines the respiratory zone?
Participates in gas exchange.
What cell type predominates in the respiratory zone?
Cuboidal cells in respiratory bronchioles, simple squamous cells in alveoli
What clears debris in the respiratory zone?
Cilia terminate in respiratory bronchioles, alveolar macrophages clear debris and participate in immune response.
What kind of cell lines the alveolar surfaces?
97% Type I pneumocytes. Squamous, thing for optimal gas diffusion.
What is the purpose of Type II pneumocytes? What cell type are they?
- Secrete surfactant
- Serve as precursors to Type I cells and other Type II cells - proliferate during lung damage.
They are cuboidal and clustered.
What are Clara/club cells?
Non-ciliated low columnar/cuboidal with secretory granules. Secrete component of surfactant, degrade toxins, act as reserve cells.
How does surfactant prevent collapse?
Decreases surface tension; otherwise too much surface tension would push alveolus closed.
When are alveoli at greatest risk of collapse?
Expiration (smallest radius)
What is the equation for collapsing pressure of the lung?
collapsing pressure = 2(surface tension)/radius
What is pulmonary surfactant?
Complex mix of lecithins - most important: dipalmitoylphosphatidlycholine.
When does surfactant synthesis begin?
week 26
When is surfactant synthesis complete?
Week 35 - mature levels.
How can amniotic fluid asses fetal lung maturity?
Lecithin:sphingomyelin ratio > 2.0 indicates lung maturity.
How many lobes does the left lung have?
Two lobes + lingula. One less lobe to make room for the heart.
How many lobes does the right lung have?
Three lobes.
Where is an aspirated jellybean most likely to enter?
Right main stem bronchus
