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26 Cards in this Set
- Front
- Back
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How many generations does the bifuraction pattern go through? How does the diameter of the airway change through bifurcation?
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*23 generations
*diameter decreases from 25mm to 0.25mm |
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What is the action of the diaphragm in inspiration? What percentage of the change in volume of the thoracic cavity is accounted for by the action of this muscle?
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*as it contracts the volume of the thoracic cavity is increased
*accounts for 85% of the volume change |
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Contraction of the external intercostals produces what kind of action? When is this used?
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*contraction lifts the ribs upwards and outwards to increase the volume of the thoracic cavity
*used during active inspiration |
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T/F:
During normal tidal breathing, expiration is an active process. |
False: it is a passive process.
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What muscles are used to effect active expiration?
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*abdominal muscles
*internal intercostals |
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What is alveolar pressure at end expiration? What is air flow at this point?
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*alveolar pressure is zero
*there is no air flow |
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Where is the intrapleural space located? How much fluid in contained in this space?
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*between the outer covering of the lungs and the inner covering of the ribs
*contains ~2mL of fluid |
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What is IPP at end expiration? What produces this pressure?
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*-5 cmH2O
*produced by the tendency of the lungs to collapse and the tendency of the ribs to spring outward |
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What is IPP during inspiration? What causes this change? How does this affect alveolar pressure?
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*IPP become -8
*an increase in the volume of the thoracic cavity causes this *alveolar pressure becomes -1 |
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What is transmural pressure? How can it be calculated?
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*the pressure across the alveolar wall or respiratory membrane
*equal to alveolar pressure minus IPP |
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What is transmural pressure at end expiration? During inspiration?
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*end expiration: 0 - (-5) = +5
*inspiration: (-1) - (-8) = +7 |
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At what point of the respiratory cycle does alveolar pressure reach its peak? IPP?
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*alveolar pressure peaks at mid-inspiration
*IPP peaks at the end of inspiration |
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T/F:
Expiration takes twice as long as inspiration during normal tidal breathing. |
This is true and is due to the fact that expiration is a passive process.
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What is a pneumothorax? How can it be caused? What effects does it have?
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*the entry of air into the IP space, thus disrupting the pressure gradient
*trauma (from the outside) or infection (from the inside) *disruption of the pressure gradient causes lung collapse |
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What is tidal volume? What is a normal value?
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*the air moved in and out of the lung during normal breathing
*0.5-1 L |
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Give the series of events that leads to development of subatmospheric alveolar pressure.
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1. Inspiratory muscles contract
2. Thoracic cavity expands 3. IPP becomes more negative 4. Transmural pressure increases 5. Alveolar pressure becomes more negative and air enters. |
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What is the inspiratory reserve volume? The inspiratory capacity?
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*IRV = amount of air that can be inspired past tidal volume
*IC = TV + IRV |
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What is expiratory reserve volume?
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The amount of air that can be expired past tidal volume.
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What is vital capacity? How can it be calculated?
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*the maximum volume of gas that can be forcibly expired after maximal inspiration
*VC = IRC + TV + ERV |
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What is residual volume?
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The amount of air left in the lungs after forcible expiration (i.e. after ERV has been reached)
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What is functional residual capacity? How can it be calculated?
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*volume remaining in the lungs after tidal expiration
*FRC = RV + ERV |
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What is total lung capacity? How can it be calculated? What is a normal value?
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*the total volume of the lungs from maximum inspiration to residual volume
*TLC = RV + ERV + TV + IRV *6L for 70-kg person |
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What are two methods of measuring residual volume?
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1. Helium inspiration method (inaccurate for patients with obstructed airways)
2. Body plethysmograph |
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What changes in lung volumes can be expected in patients with obstructive lung disease?
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*FRC and RV are increased
*VC is decreased *TLC may increase in chronic conditions |
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What changes in lung volumes can be expected in patients with fibrotic restrictive lung disease?
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A decrease in TLC, FRC, and RV
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What changes can be expected in patients experiencing restrictive lung function due to obesity?
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*TLC and RV remain constant
*FRC decreases |
