overview of respiration and respiratory mechanics (R2) Flashcards
accessory musces of inspiration
(contract only during forceful inspiration)
- sternocleidomastoid
- scalenus
muscles of active inspiration
(contract only during active inspiration)
- internal intercostal muscles
- abdominal muscles
major muscles of inspiration
(contract every inspiration; relaxation causes expiration)
- external intercostal muscles
- diaphragm
- (ribs and sternum are also involved)
tidal volume (TV)
- volume of air entering or leaving the lungs during a single breath
- average value = 500ml
inspiratory reserve volume (IRV)
- extra volume of air that can be maximally inspired over and above the typical resting tidal volume
- average value = 3000ml
inspiratory capacity (IC)
- maximum volume of air that can be inspired at the end of a normal quiet expiration (IC=IRV+TV)
- average value = 3500ml
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
- average value = 1000ml
residual volume (RV)
- minimum volume of air remaining in the lungs even after a maximal expiration
- average value = 1200ml
functional residual capacity (FRC)
- volume of air in lungs at end of normal passive expiration (FRC = ERV + RV)
- average value =2200ml
vital capacity (VC)
-maximum volume of air that can be moved out during a single breath following a maximal inspiration
(VC = IRV + TV + ERV)
-average value = 4500ml
total lung capacity (TLC)
-maximum volume of air that the lungs can hold
(TLC = VC =RV)
-average value = 5700ml
forced expiratory volume in one second (FEV1): Dynamic Volume
- volume of air that can be expired during the first second of expiration in an FVC (forced vital capacity)
- average volume = FEV1%= FEV1/FVC ratio, normally >75%
factors that affect normal predicted values of lung volumes and capacities
age, gender, height etc
spirometry definition/ function
-common office test used to assess how well your lungs work by measuring how much air you inhale, how much you exhale and how quickly you exhale. Spirometry is used to diagnose asthma, chronic obstructive pulmonary disease (COPD) and other conditions that affect breathing
spirometry for dynamic lung volumes (volume time curve)
allows you to determine;
- FVC
- FEV1
- FEV1% (FEV1/FVC ratio)