Term
| These volumes and capacities cannot be measured directly by a spirometer |
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Definition
1. Residual Volume (RV)
2. Functional Residual Volume (FRC)
3. Total Lung Capacity (TRC) |
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Term
| This volume in the respiratory system is measured as the volume exchanged during quiet breathing. |
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Definition
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Term
| This important respiratory diagnostic value is the amount of volume that can be forcibly expired in one second. It is severely decreased in patients with COPD. |
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Definition
| Forced Vital Capacity (FEV1) |
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Term
| The total lung capacity (TLC) in a typical individual. |
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Definition
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Term
| The volume of air left in the lungs following maximal expiration. |
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Definition
| Residual Volume (RV). Usually 1-2L. |
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Term
| The volume in lungs at the end of passive expiration. |
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Definition
Functional Residual Capacity (FRC)
ERV+RV |
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Term
| Volume moved between end tidal expiration and total lung capacity. |
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Definition
Inspiratory Capacity
VT+IRV |
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Term
| The volume of air moved between TLC and RV. |
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Definition
| Vital Capacity (normally 4-5L) |
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Term
| Volume of air form the end of tidal inspiration to total lung capacity. |
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Definition
| Inspiratory reserve volume |
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Term
| volume in lung from the end of tidal expiration to forced expiration end volume. |
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Definition
| Expiratory reserve volume |
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Term
| This respiratory volume greatly increases with an obstructive pulmonary disease such as COPD. |
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Definition
Residual volume.
Lung is overinflated.
Results in less effective tidal volume (greater air dilution due to increased volume in lung) |
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Term
| This respiratory volume decreases during a restrictive lung disease such as fibrosis. |
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Definition
Reserve volume.
Lung is less compliant; hard to fill. |
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Term
| This lung capacity decreases in both obstructive and restrictive pathology. |
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Definition
Vital Capacity
(IRV+TV+ERV) |
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Term
| When moving from a standing to supine position, this respiratory volume decreases. Why? |
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Definition
End reserve volume.
Gravity is no longer opposing abdominal contents from pushing up on the diaphragm, allowing the diaphragm to be pushed up further when relaxed, decreasing end reserve volume. |
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Term
What is the equation and term to describe the total volume of air entering or leaving the lungs per minute?
The Alveoli per minute?
What is the relationship between each? |
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Definition
Minute Ventilation
(Tidal volume X breath rate)
Typically 7.5L/min
Alveolar ventilation
(Total lung volume-Dead space volume) X breath rate
Minute ventilation > Alveolar ventilation |
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Term
| What is a good way to measure alveolar minute ventilation? |
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Definition
| Measure pulmonary blood flow; they should closely match in an otherwise healthy lung. |
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Term
What is the difference between anatomical dead space and alveolar dead space?
What is physiological dead space? |
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Definition
Anatomical dead space-inspired air in conducting airways that does not participate in gas exchange.
Alveolar dead space-The volume of gas in alveoli with little or no perfusion.
Physiological dead space is the sum of these two values; it is much larger in patients with lung disease. |
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Term
| Why is alveolar dead space considered "wasted ventilation"? |
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Definition
| Because there is no perfusion, the energy used to fill these alveoli with fresh air is for nothing; the oxygen cannot be accessed. |
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Term
What is the main factor in blood which controls ventilation rate and depth?
How is this factor detected? |
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Definition
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Term
PaCO2 Levels less than 35mmHg.
What can cause this? |
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Definition
hypocapnia
Hyperventilation |
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Term
PaCO2 Levels greater than 45mmHg.
What can cause this?
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Definition
hypercapnia
Hypoventilation |
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Term
What is the equation for arteriolar oxygen pressure?
What can this value be used for? |
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Definition
PAO2=(PB-PH2O) X FIO2-PACO2/R
Where PB=Barometric pressure (760mmHg)
PH2O=Vapor pressure of water (76mmHg)
FIO2=Fraction of Air that is O2 (0.21)
R=Respiratory exchange ratio=O2 used/CO2 Produced; 0.8
The Alveolar Gas Equation.
This can then be used to calculate the (A-a) gradient. |
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Term
| When is the A-a gradient indicative of pathology? |
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Definition
The gradient being greater than 20mmHg; indicates abnormal gas exchange caused by a poor ventilation/perfusion ratio.
useful in determining if abnormal gas exchange is due to hypoventilation or not. |
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Term
| Why is there less ventilation at the top of the lung than the bottom? |
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Definition
| Gravity aids in the recoil force of the lung at its top. Thus, pleural pressure at the apex of the lung is more negative. |
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Term
what happens to pleural pressure during inspiration?
Why? |
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Definition
Becomes more negative.
The chest wall force and recoil force of the lung increase with inspiration, causing the difference between the two to increase. |
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Term
| Why is pleural pressure directly important in respiration? |
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Definition
| Pleural pressure is transmitted to alveoli which allows them to have the ability to "suck air" into them due to sub-atmospheric pressure conditions. |
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Term
What is the ventilation perfusion ratio typically at the apex of the lung?
Is this counterintuitive given the nature of ventilation at the top of the lung than at the bottom? |
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Definition
Vent/Perf=about 3.
This is counterintuitive because although ventilation decreases at the top of the lung, perfusion decreases even more; becoming the limiting factor of the vent/perf ratio. |
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Term
| Name the term that describes the inverse of compliance that often increases in restrictive respiratory diseases. |
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Definition
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