Respiratory - Lung Properties Flashcards
How well a lung inflates or deflates with a change in transpulmonary pressure depends on its…
Elastic properties
An important feature of an elastic material: once stretched, it recoils to its unstretched position
Define
Compliance
How easily lung stretched (distensibility
ΔV/ΔP
High compliance
Large ΔV for a given ΔP
Low compliance
Small ΔV for a given ΔP
Increase ΔV -> _ Compliance
Increases
What affect does gravity have on lungs?
It causes the weight of lung (80% water) to pull down to alveoli
Gravity pulling down on lungs causes alveoli in apex to be more expanded
Slinky
Where in the lung is compliance greater?
compliance in the base is greater than the apex
More tidal volume goes to…
base
bottom alveolii not as stetched at start
Example of Low compliance
disease/disorder
Pulmonary fibrosis
collagen deposition due to lung injury - high elastic recoil
Example of highly compliant lung
Emphysema
Disappearing tung tissue - low elastic recoil
Normal lung compliance affect on volume
Lung elastic recoil and chest wall elastic recoil equal
Emphysema lung compliance affect on lung volume
Destroy some lung tissue -> decrease recoil -> Chest wall recoil wins out
Fibrosis lung compliance affect on lung volume
Extra lung tissue -> increase recoil -> Lung recoil wins out
What are the functions of surfactant?
Lowers surface tension in alveoli
Keeps alveoli dry
How does surfactant decrease surface tension in alveoli? What is it’s purpose?
Strong force of attraction of water is decreased by surfactant
Increases compliance of lung making it easier to inflate
