Respiratory: Compliance Flashcards
What is lung compliance?
A measure of elasticity and ‘stretch’ - volume changer per unit pressure change
What are some factors than decrease compliance?
Supine or prone position - reduced AP motion
Restrictive pathologies eg fibrosis
High position of diaphragm in obesity/pregnancy
What is the role of surfactant?
Surfactant reduces surface tension by breaking the H bonds, making the lungs easier to inflate - increases compliance.
It is produced by type 2 alveolar cells (pneumocyte)
It stops alveoli collapsing into each other
What happens to the pressure inside a bubble when the radius increases?
The pressure decreases, therefore if a big bubble is connected to a small bubble then the pressure will flow from high pressure to low pressure and the small bubbles will collapse into the big bubble.
What is infant respiratory distress syndrome?
Babies born less than 36 weeks have too little surfactant so their breathing and gas exchange in compromised.
What region of the airways has the highest resistance?
Although the small airways have higher resistance, this is decreased by there being lots of airways in parallel.
Therefore the large airways have the highest resistance.
