Ventilation and Compliance 1,2/ Lung Volumes and Ventilation Flashcards
what is the tidal volume (TV)?
the volume of air breathed out of the lungs at normal each breath (ex: between end of normal inspiration and end of normal expiration)
what is the expiratory reserve volume (ERV)?
the maximum volume of air which can be expelled from the lungs at the end of a normal expiration
what is the inspiratory reserve volume (IRV)?
the maximum volume of air which can be drawn into the lungs at the end of a normal inspiration
what is the residual volume (RV)?
the volume of gas in the lungs at the end of a maximum expiration
what is the vital capacity (VC)?
the tidal volume + the reserve volumes (IRV + ERV + TV). Basically the maximum tidal volume you can have
what is the inspiratory capacity (IC)?
the tidal volume + the inspiratory reserve volume (TV + IRV). Basically, starting from a resting point; the maximum air volume you can inhale
what is the functional residual capacity (FRC)?
the expiratory reserve volume + residual volume (ERV + RV). When resting, the volume which doesn’t move in an out (has functional role a residue?)
what is the FEV1?
the forced expired volume in 1 second (max you can expire in 1 sec)
what corresponds to FEV1/FVC?
the fraction of forced vital capacity expired in 1 second (max you can expire in 1 sec as a proportion of max you can expire in one go)
what is the anatomical dead space for the respiratory system? what’s its value?
corresponds to the volume of gas occupying the airways and this gas is not available for exchange, its value is 150mL
what does the term “ventilation” broadly refer to?
the movement of air in and out of the lungs (#breathing)
what is pulmonary ventilation?
total air movement into/out of lungs (relatively insignificant in functional terms), measured in L/min
“product of tidal volume and respiratory frequency”
what is alveolar ventilation?
fresh air getting to alveoli and therefore available for gas exchange (functionally much more significant), measured in L/min
how do pulmonary and alveolar ventilation differ in value?
- pulmonary ventilation = tidal volume
- alveolar ventilation = tidal volume - volume of anatomical dead space
what is the definition of partial pressure? (HINT: it’s about the pressure of a single gas in a mixture of multiple gases)
the pressure of a gas in a mixture of gases is equivalent to the percentage of that particular gas in the entire mixture multiplied by the pressure of the whole gaseous mix (expressed in mmHg or kPa)
under normal conditions, how do PO2 and PCO2 vary?
resting alveolar PO2 and PCO2 are fairly constant, because the percentage of oxygen in the atmosphere is constant
during hyper-ventilation, how do the partial pressures of O2 and CO2 vary?
increased alveolar PO2 rises and increased alveolar PCO2 decreases, because the percentage of oxygen in the lungs increases (to the detriment of the percentage of carbon dioxide), atmospheric pressure is still constant
during hypo-ventilation, how do the partial pressures of O2 and CO2 vary?
decreased alveolar PO2 decreases and decreased alveolar PCO2 increases, because the percentage of oxygen in the lungs decreases (to the benefit of the percentage of carbon dioxide), atmospheric pressure is still constant
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what is the point of residual volume?
so the alveoli don’t collapse- it is easier to make them open up once they are already partially inflated (also gas exchange can happen all the time)