1- Respiratory Mechanics Flashcards
what are the major inspiratory muscles?
diaphragm & external intercostal muscles
what are the accessory muscles of inspiration?
sternocleidomastoid, scalenus, pectoral
(they only contract in forceful inspiration)
what are muscles of active expiration?
abdominal muscles & internal intercostal muscles
what lung volumes and capacities can be measured by spirometry?
- tidal volume (normal amount breathing in 1 breath)
- inspiratory reserve volume (extra volume that can breathe in if really try)
- expiratory reserve volume (the amount that’s left to breathe out after inspiratory capacity)
- inspiratory capacity (everything you can breathe in)
- vital capacity (everything that can be used)
what volumes and capacities can not be measured by simple spirometry?
- residual volume (the amount of breath that will never be breathed in or out)
- functional residual capacity (the residual volume & expiratory reserve volume)
- total lung capacity
*basically any capacity/volume involving residual volume
what is tidal volume and what is average value?
volume of air entering or leaving lungs during a single breath = 0.5L
what is inspiratory reserve volume (IRV)?
extra volume of air that can be maximally inspired over & above the typical resting tidal volume = 3L
what is expiratory reserve volume (ERV)?
extra volume of air that can be actively expired by maximal contraction beyond the normal volume of air after a resting tidal volume = 1L
what is residual volume (RV)?
minimum volume of air remaining in the lungs even after maximal expiration = 1.2 L
what is inspiratory capacity (IC)?
max volume of air that can be inspired at end of normal quiet expiration = 3.5 L
(inspiratory reserve volume + tidal volume)
what is functional residual capacity (FRC)?
volume of air in lungs at end of normal passive expiration = 2.2 L
(expiratory reserve volume + residual volume)
what is vital capacity? (IMPORTANT)
max volume of air that can be moved out during a single breath following max inspiration = 4.5 L
(inspiratory reserve volume + tidal volume + expiratory reserve volume)
what is total lung capacity?
total volume of air lungs can hold = 5.7 L
(vital capacity + residual volume)
when does residual volume increase?
residual volume = volume of air remaining in the lungs even after maximal expiration
increases when elastic recoil of lungs is lost (as less air can be released)
what is forced vital capacity? (FVC)
maximum volume that can be forcibly expelled from the lungs following a maximum inspiration