Term
| What is the Tidal Volume (TV)? |
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Definition
| volume inspired or expired with each normal breath |
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Term
| What is the inspiratory reserve volume (IRV)and when is it used? |
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Definition
| volume that can be inspired over and above the tidal volume; it is used during exercise |
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Term
| What is the expiratory reserve volume (ERV)? |
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Definition
| volume that can be expired after the expiration of a tidal volume |
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Term
| What is the residual volume (RV) and what cannot be used to measure it? |
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Definition
| volume that remains in lungs after maximal expiration; cannot be measured by spirometry |
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Term
| What is anatomic dead space and what is its normal value? |
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Definition
| volume of conducting airways; normally around 150mL |
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Term
| What is the physiological dead space and how does it compare to the anatomical dead space? |
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Definition
| volume of lungs that does not participate in gas exchange; may be larger than anatomical dead space diseases where there are ventilation/perfusion deficits |
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Term
| What is the minute ventilation and how is it calculated? |
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Definition
| amount of volume ventilated in a minute; minute ventilation=tidal ventilation*breaths/min |
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Term
| What is the alveolar ventilation? |
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Definition
| alveolar ventilation=(tidal volume-dead space)*breaths/min |
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Term
| What is the inspiratory capacity? |
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Definition
| sum of the tidal volume and inspiratory reserve volume (IRV) |
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Term
| What is the functional residual capacity (FRC)? |
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Definition
| sum of the expiratory reserve volume and residual volume; aka volume remaining in lungs after tidal volume is expired; cannot be measured by spirometry |
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Term
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Definition
| sum of tidal volume, inspiratory reserve volume, and expiratory reserve volume; volume of air that can be forcibly expired after a maximal inspiration |
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Term
| What is total lung capacity? |
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Definition
| sum of all four lung volumes (IRV, TV, ERV, and RV); volume in lungs after maximal inspiration; cannot be measured by spirometry |
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Term
| Name the lung volumes which cannot be measured by spirometry. |
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Definition
| 1. residual volume; 2. functional reserve volume; 3. total lung capacity |
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Term
What is the forced expiratory volume (FEV1) and what is its normal value? |
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Definition
volume of air that can be expired in the first second of forced maximal expiration; normal value is 80% of forced vital capacity (FEV1/FVC) |
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Term
| What is the equation to determine physiological dead space? |
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Definition
| VD=VT*(PACO2-PECO2)/PACO2; this fraction represents the dilution of CO2 pressure by dead-space air |
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Term
| How does the FEV1 change in obstructive lung disease? in restrictive lung disease? |
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Definition
| in obstructive lung disease FEV1 is reduced more than FVC so the ratio is decreased; in restrictive lung disease both FEV1 and FVC are reduced so the ratio is either normal or is increased |
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Term
| What is the function of the diaphragm? |
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Definition
| it contracts and abdominal contents are pushed down and ribs are lifted upwards to increase the volume of the thoracic cavity |
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Term
| What are the major accessor muscles for inspiration and when are they used? |
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Definition
| external intercostals; used during exercise and respiratory distress |
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Term
| What are the muscles of expiration and when are they used? |
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Definition
| abdominal muscles-compress abdominal cavity to push air out of the lungs, and internal intercostals-pull ribs downward and inward; used during exercise or when airway resistance is increased |
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Term
| What describes compliance and what is it related to? |
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Definition
| C=V/P and describes the distensibility of the lungs and chest wall; it is inversely related to elastance and stiffness |
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Term
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Definition
| difference between the inflation of the lung curve versus deflation of the lung curve in pressure-volume graph |
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Term
| What is transmural pressure? |
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Definition
| it is alveolar pressure minus the intrapleural pressure |
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Term
| Name the characteristics at high expanding pressures |
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Definition
| compliance of the lung is lowest, lungs are least distensible, and pressure volume curve flattens |
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