Lung Anatomy and Development Flashcards
How are the upper and lower lobes distinguished?
Divided by the oblique fissure
Upper and middle lobes are anterior
Lower lobe is posterior
Horizontal fissure
Creates the middle lobe on the right lung
Lingula
Part of the left upper lobe isolated by the cardiac notch
What is the benefit of separation of the lungs?
Lobe differentiation promotes uniform expansion
generally the lower lobe fills first, fissures allow the upper lobe to expand unimpeded
Cupola
Apex of the lung
Extending into the neck above the 1st rib
Hilum
Root of lung
Entry point for bronchi, pulmonary vein, nerves, etc
What are the primary, secondary and tertiary portions of the bronchial tree?
Main (primary) bronchus to each lung
Lobar (secondary) bronchus to each lobe
Segmental (tertiary) one for each broncho-pulmonary segment (10 of them forming the functional lung)
Carina
Tracheal bifurcation
Asymmetrical: right side is more vertical and likely to lodge objects, while left side is more horizontal because of the location of the heart
Where would you find the respiratory epithelium?
(pseudostratified ciliated columnar epithelium)
Extends from the nasal cavity, through the trachea and into the bronchioles
What are the three cell types found in the respiratory epithelium?
- Ciliated: form the mucociliary escalator; each cell has 250ish cilia sweeping mucus coat towards the mouth
- Mucus: (goblet) release mucin that adheres to particles; cells increase in number during chronic irritation
- Basal: replicate to replace epithelial cells
What makes up the trachea?
Mucosa, submucosa, cartilage rings, trachealis muscle, and adventitia
What is the mucosa?
Respiratory epithelium (ciliated and mucous cells) Lamina propria (CT)
What is submucosa?
Loose CT containing mucous glands and diffuse lymphatic tissue
What are cartilage rings?
C-shaped rings that maintain the patency of air Hyalin cartilage (chondrocytes in matrix) Avascular, but having a high concentration of glycosaminoglycans permits diffusion of fluid from blood vessels to chondrocytes
What is the trachealis muscle?
Smooth muscle attached to free ends of cartilage ring regulating wall tension
What is adventitia?
CT binding trachea to neighboring structures
What are bronchi made up of?
Mucosa + respiratory epithelium, basement membrane, muscularis mucosa + SM, submucosa + mucous glands, cartilage, discontinuous plates, adventitia
What are bronchioles made up of?
Mucosa: Resp. epithelium with simple columnar an cuboidal ciliated cells (fewer mucus cells)
Cartilage: not many; makes them susceptible to collapse with external pressure
Muscularis mucosa: extensive SM and elastic CT
What do terminal and respiratory bronchioles also have?
Clara cells: dome shaped, secrete lipoprotien preventing luminal adhesion if airway collapses and a secretory protein released during asthma
What do the terminal bronchioles feed into?
Secondary lobule: unit of tissue branching into several primary lobules forming polygonal patterns on the lung surface
What do the respiratory bronchioles feed into?
Acinus (primary lobule): unit containing alveolar ducts, sacs and alveoli where gas exchange occurs
What do type I alveolar cells form?
(pneumocytes) form most of the alveolar epithelium
What do type II alveolar cells do?
(pneumocytes) release surfactant and surfactant proteins
Surfactant
- Reduces surface tention and air-epithelium interface
- Prevents alveolar collapse with exhalation
- Post week 35, cells release DPPC
What do alveolar pores do?
Interconnect adjacent alveoli and equalize their pressures; permit bacterial passage for spread of infection
Alveolar macrophages
Ingest particulate matter
Can be found up bronchial tree in mucus, remain in local CT, of pass thru superficial and deep lymphatics into nodes