L35: Mechanics Of Breathing Flashcards
What are the accessory muscles used on respiration during exercise?
Scalenes and SCM
What nerves fire to stimulate inspiration?
Phrenic and intercostal nerves
What happens to pressure and air flow when the diaphragm contracts?
The diaphragm contracts and descends, increasing the volume of the thoracic cavity. The lungs must follow this and expand. This results in a decrease in intra-alveolar pressure and air flows down its concentration gradient into the lungs.
What 3 pressures are involved in respiration?
Atmospheric, intra-alveolar, and intra-pleural
When does atmospheric pressure decrease?
Increased altitude
What is the equation for transmural pressure?
Transmural pressure= alveolar pressure- intrapleural pressure
Which is always greater, intra-alveolar pressure or intrapleural pressure?
Intra-alveolar pressure
What is responsible for the fact that the lung is always stretched to some degree, even during respiration?
Transmural pressure gradient
What does more elastic tissue mean for compliance?
Compliance is decreased
The slopes on the V/P pressure loops for inspiration and expiration are different. What do you call this?
Hysteresis
Why are the slopes for inspiration an expiration different on the P/V loop?
The slope gives the compliance of the isolated lung and compliance is different with inspiration and expiration
When is compliance generally measured?
During expiration
Normally, the intrapleural pressure has *** pressure?
Negative (less pressure in intrapleural than atmosphere)
What creates the negative intrapleural pressure?
The two opposing elastic forces of the lungs and the chest wall pulling in opposite directions
What is emphysema?
An obstructive lung disease that involves loss of elastic fibers in the lungs secondary to increased protease and elastases
