What are the two zones of the respiratory tree?
Conducting and Respiratory zones
What does the conducting zone of the respiratory tree consists of?
Large airways of nose, pharynx, trachea, and bronchi Small airways of bronchioles and terminal bronchioles
Function of conducting zone
warms, humidifies, and filters air does NOT participate in gas exchange
What is the anatomic dead space?
Conducting zone (where gas exchange does not happen)
What special histological features extend to the end of bronchi?
Cartilage Goblet cells
Histology of oropharynx, laryngopharynx, anterior epiglottis and upper half of the posterior epiglottis, vocal folds?
Stratified squamous epithelium
Histology of conducting zone to the end of terminal bronchioles
Pseudostratified ciliated columnar cells (nose, paranasal sinus, most of larynx, tracheobronchial tree) Beat mucus up and out of lung Smooth muscle of airway walls
What is the respiratory zone?
Consisting of respiratory bronchioles, alveolar ducts and alveoli
Function of the respiratory zone
Histology of the respiratory zone
Cuboidal cells in respiratory bronchioles Simple squamous cells up to alveoli (No cilia - only up to respiratory bronchioles
Function of alveolar macrophages
Clear debris and participate in immune response
What are type I pneumocyte cells?
Thin cells that line the alveoli (squamous) for gas diffusion
97% of alveolar surfaces are covered by?
Type I pneumocyte cells
What are type II pneumocyte cells?
Secrete pulmonary surfactant to prevent atelectasis Also the precursors to type I and other type II cells
Histology of type II pneumocyte cells
cuboidal and clustered
What cells proliferate during lung damage?
Type II pneumocyte cells (regenerates the tissue)
What are clara cells?
nonciliated columnar cells with secretory granules secrete component of surfact and degrade toxins - act as reserve cells
What is LaPlace's law?
P = 2T/r (P = collapsing pressure, T=tension, r=radius)
Under LaPlace's law, do larger or smaller alveoli tend to collapse and why?
Smaller radius tend to collapse as pressure increases (e.g. tendency to collapse on expiration as radius decreases)
What is pulmonary surfactant made of?
Mix of lecithins (most important is dipalmitoylphosphatidylcholine)
When does surfactant synthesis begins?
Week 26 of gestation Mature level are not achieved until around week 35
What value indicates fetal lung maturity?
lecithin to sphingomyelin ratio > 2.0 in amniotic fluid
How many lobes of lung on left and right?
3 lobes on right
2 lobes on left (+ lingua)
What is the homologue of right middle lobe on the left side?
Which lung is the more common site for inhaled foreign body? Why?
Right main stem bronchus is wider and more vertical than the left
If you aspirate a peanut while upright, where would you expect to find it?
Lower portion of right inferior lobe
If you aspirate a peanut while supine, where would you expect to find it?
Superior portion of right inferior lobe
What is the relationship of the pulmonary artery to the bronchus on the left and right side?
Right side - Anterior to main stem bronchus
Left side - Superior to main stem bronchus
Injury to the 5th intercostal space at mid-clavicular line would damage which structure?
(Left ventricle forms apex and reach as far as the 5th space. All other chambers lie medial to the left midclavicular line)
What are the fissures of the lung on the right and left side?
Right side: Horizontal fissure (superior and middle lobes); Oblique fissure (middle and inferior lobes)
Left side: oblique fissure (superior and inferior lobes)