Mechanisms of Breathing/Compliance Flashcards
What muscles are used in inspiration?
Diaphragm, external intercostals, sternomastoids, scalenes.
What muscles are used in expiration?
Passive normally, in forced use abdominal wall and internal intercostals.
How does obstructive disease affect the diaphragm?
Disease causes high volume breathing that shortens the diaphragm causing decreased contraction and mechanical advantage.
What is intrapleural pressure?
Pressure within the intrapleural space which is generated by the intrinsic elastic properties of the lung and chest wall as they deviate from their equilibrium positions.
What is the equilibrium force of the lung?
Inward towards deflation
What is the equilibrium force of the chest wall?
Outward towards expansion
What is the typical value of intrapleural pressure?
Negative, more negative at the end of inspiration.
What is the relationship between mouth and lung pressure during inspiration?
Lung pressure is less than mouth pressure
What is the relationship between mouth and lung pressure during inspiration?
Lung pressure is more than mouth pressure
What is the definition of compliance?
The change in volume per change in pressure
At what phase of the breath cycle is compliance highest?
At rest, the end of expiration (low volume)
At what phase of the breath cycle is compliance lowest?
At the end of inspiration (high volume)
What change in compliance does fibrosis cause?
Low compliance
What change in compliance does emphysema cause?
High compliance
