Term
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Definition
| Tests that are used to determine lung function based on comparison between expected values and experimental values. Note: Stethoscope cannot help you determiner lung volume. X-ray can, however, it is difficult to get a precise lung volume measurement (e.g. can be used to determine if there is "too much" air or fluid" |
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Term
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Definition
| Lung volume constant with time. No AIRFLOW. |
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Term
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Definition
| Lung volume changing with time. AIRFLOW. |
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Term
| Characteristics of the Lungs |
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Definition
- sponge like
- complex airway tree within parenchyma (lung tissues)
- complex vascular network
- airways branch asymmetrically |
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Term
| Under normal conditions, are respiratory muscles used during INSPIRATION? Why or why not? |
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Definition
| YES! Respiratory muscles are required to expand the thorax and generate negative pressure so that air is sucked in to the lungs. |
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Term
| Under normal conditions, are respiratory muscles used during EXPIRATION? Why or why not? |
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Definition
| NO. Expiration is a passive event that occurs based on the increase in pressure toward atmospheric AND the elastic recoil of the lung and the chest wall (when the chest wall is pushed to it's maximum). Therefore, they are only used in disease states and during exercise or forced expiration. |
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Term
| When airflow is absent, the pressure across the lungs reflects ________________________ (static conditions). When airflow is present, the pressure across the lungs reflects _____________________ and __________________ (dynamic conditions). |
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Definition
| When airflow is absent, the pressure across the lungs reflects ITS ELASTIC PROPERTIES (static condition). When airflow is present, the pressure across the lungs reflects ELASTIC and RESISTIVE properties of the lungs (dynamic conditions). |
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Term
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Definition
- the amount of air that goes in and out on a normal breathe
- approximately 5 mL/kg (changes with weight) |
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Term
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Definition
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Term
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Definition
a. Vital Capacity
b. Total Lung Capacity |
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Term
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Definition
- take a deep breathe in and blow out as hard as possible
- this is the most that you can empty your lungs
- tidal volume + inspiratory capacity + expiratory reserve volume = vital capacity |
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Term
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Definition
a. Vital Capacity
b. Total Lung Capacity
c. Residual Volume |
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Term
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Definition
- the amount of air left in your lungs when you blow out as hard as possible
- if you were able to blow out the residual volume the lungs would completely collapse
- note: there is more force needed to put the first breathe in then to continue blowing once the lungs are already expanded. Residual volume prevents this.
- residual volume + vital capacity = total lung capacity |
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Term
| Functional Residual Capacity |
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Definition
- amount of air left in the lungs on normal breathing
- will be greater than the residual volume (because not forced)
- equilibrium point between forces pulling the lungs in and pushing them out
- inspiratory capacity + functional residual capacity = total lung capacity |
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Term
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Definition
a. Residual Volume
b. Functional Residual Capacity
c. Total Lung Volume
d. Inspiratory Capacity |
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Term
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Definition
- the max amount of air that can be inspired from functional residual capacity
- inspiratory capcity + functional residual capacity = total lung volume |
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Term
| Expiratory Reserve Volume |
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Definition
- the difference between your functional residual capacity and residual volume
- how much you can breathe out after an normal expiration |
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Term
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Definition
a. Inspiratory Reserve Volume
b. Expiratory Reserve Volume
c. Residual Volume
d. Vital Capacit
e. Total Lung Capacity
f. Inspiratory Capacity
g. Functional Residual Capacity
h. Total Lung Capacity (again! tricky!) |
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Term
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Definition
- measures the volume of gas entering or leaving the mouth over time
- measures the subdivisions of vital capacity but does not measure the residual volume (because RV is what is left in your lungs)
- this also means that it can't measure the FRC or the TLC |
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Term
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Definition
| The volume of air that you can push out in the first second of a forced maneuver. |
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Term
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Definition
| How much of your lung volume you can expired with a forced maneuver. |
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Term
| What is the FEV.01/FVC ratio and what does it tell you? How would obstructive and restrictive disease effect the FEV0.1/FVC ratio? |
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Definition
| The FEV0.1/FVC ratio indicates how much of the forced vital capacity you blow out in the first second. For someone with an obstructive disease, the ratio will be lower because it is more difficult to push out the first breathe due to airway collapse/obstructive -- however, given enough time to expire, the vital capacity should not be changed. For someone with restrictive disease, the ratio should be normal or a big higher than normal, because both the FEV0.1 and FVC decrease due to stiffening of the lungs and the airways. |
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Term
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Definition
- approach used to measure FRC or RV
- a patient inhales a gas of known volume and concentration
- the gas then dilutes based on the total amount of air in the lungs
- the final volume can then be calculated using C1V1 = C2V2 |
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Term
| Plethysmography (Body Box) |
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Definition
- uses Boyle's Law (P1V1 = k)
- Closed container whose volume can be adjusted so that the pressure in the container increases in proportion to the fractional decrease in container volume
- way to measure TLC |
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Term
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Definition
- used to estimate the volume of gas in the lung by measuring the outline of the lung on a radiograph
- for more precise estimates of TLC, a CT scan can be used |
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Term
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Definition
| Airway Opening Pressure (pressure taken at the mouth) |
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Term
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Definition
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Term
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Definition
| Transmural Pressure - measure of pressure difference across a wall |
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Term
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Definition
Transpulmonary pressure - difference between the pressure in the lungs and the pressure in the plural space.
Ptp = Pao - Ppl |
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Term
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Definition
Pressure across both the lungs and the chest wall.
Prs = Pao - Ptm |
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Term
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Definition
- relationship between pressure and volume
- compliance is a measure of stiffness (the more stiff, the less compiant)
- the inverse of elasticity
- slope of the pressure volume curve
- CL = delta v/delta p |
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Term
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Definition
| How easily the lungs are inflated. E.g. high pulmonary compliance means that to reach a constant volume a lower amount of pressure needs to be exerted as compared to a lung with low pulmonary compliance |
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Term
| Describe the pressure-volume curve for normal inspiration. Provide the physiological explanation for the shape. |
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Definition
- the curve has an s-shape with a larger plateau at the bottom of the curve
- the plateau at the bottom of the curve is due to the fact that it takes quite a bit of pressure to increase lung volume initially (open the airways, to an extent) - must recruit closed portions of the lung
- after that it becomes linear, with a small plateau at the top due to the material limits of the lungs |
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Term
| Describe the pressure-volume curve for normal expiration. Provide the physiological explanation for the shape. |
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Definition
- the curve is an S shape with a linear portion in the middle
- the top has a plateau because due to surfactant the alveoli have an increased stability so that once they are expanded they are not easy to un-expand |
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Term
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Definition
- the difference between the inspiratory and expiratory curves
- the expiratory curve requires less energy than the inspiratory curve
- expiration is also a passive process
- extra energy that is required to inflate the lung compared to the energy recovered during deflation |
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Term
| Effect of obstructive lung disease on the P-V curve |
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Definition
- the curve is shifted up and to the left
- decreased stiffness of the lungs
- increased compliance of the lungs
- for a lesser pressure you get a greater lung volume |
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Term
| Effect of restrictive lung disease on the P-V curve. |
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Definition
- curve shifted down and to the right
- increased stiffness = decreased compliance
- this means that a greater pressure is needed to increase the volume |
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Term
| Determinants of Lung Volume |
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Definition
1) Lung Compliance
2) Chest Wall Compliance
3) Respiratory Muscles |
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Term
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Definition
FRC is the volume at which the opposing recoil forces of the lungs and chest wall balance out (e.g. equilibrium volume of the respiratory system)
- recoil of chest wall is lower, FRC will be lower
- recoil of the lungs is lower, FRC will be higher |
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Term
| Determinant of Total Lung Capacity |
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Definition
- Determined by the balance of the respiratory system elastic recoil and inspiratory muscle strength
- at high lung volumes the chest wall and the lung both want to recoil inward
- TLC is reduced by increased lung recoil and chest wall recoil or inspiratory muscles weakness |
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Term
| Determinant of Residual Volume in Youth |
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Definition
| - outward recoil of chest wall prevents muscles from emptying lungs more completely |
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Term
| Determinant of Residual Volume in Aged |
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Definition
- lung recoil and FEV0.1/FVC ratio decreases with age
- leads to premature airway closure (like in obstructive lung disease)
- weakness of expiratory muscles
- all equals a higher closing volume |
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Term
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Definition
- as lung volume decreases airways begin to close
- when a significant amount of airways have closed it limits how low the lung volumes can go and determines the RV |
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Term
| Determinants of Compliance |
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Definition
1) Tissue Forces: elastin-collagen-proteoglycan network. tissue degradation = increased compliance; scarring = decreased compliance
2) Surface Tension: dependent on surfactant production |
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Term
| Role of Pulmonary Surfactant |
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Definition
1) lowers the surface tension of the lining fluid so that we can breathe without too much effort
2) makes the alveoli stable against collapse |
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Term
| What is the effect on the pressure volume loop of taking away surfactant? |
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Definition
- decreased hysteresis
- without surfactant there is very little difference between inspiration and expiration
- the alveoli aren't stabilized |
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Term
| What is Laplace's Law? What does it mean for surfactant and alveoli? |
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Definition
Pressure = 2*surface tension/radius
- shows that pressure in a small bubble is larger than pressure in a bigger bubble
- therefore we would expect that the small alveoli would collapse into the bigger alveoli, however, this does not happen due to pulmonary surfactant
- Surfactant stabilizes Alveoli |
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Term
| Explain why there are regional differences in compliance and what this means for regional compliance. |
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Definition
- the alveolus at the top will be more stretched out, whereas the bottom will be closer together
- at the bottom they have higher compliance because they are not as stretched out as the alveolus at the top
- pleural pressure is more negative at the top than at the bottom of the lung
- the top of the lung will generally always be more stretched out and more inflated
- the lower alveolus will have more room to expand and it will be easier for them to fill (they act as if they are at a lower percentage of TLC than the upper alveolus) |
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Term
| Compare the upper and lower alveolus at TLC. |
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Definition
- At TLC whether you're at the top or the bottom of the lung both are at the plateau on the P-V curve.
- Both are fully filled and can fill no more |
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Term
| Compare upper and lower alveolus at FRC. |
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Definition
- the upper lungs are holding on to most of the reserve volume because they always have a more negative pleural pressure than the lower alveolus
- therefore at FRC, when a breathe is inhaled the lower alveoli will fill first (on the steeper part of the P-V curve than the upper alveoli that are on the plateau) |
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Term
| Compare upper and lower alveolus at RV. |
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Definition
- at residual volume you have completely blown out all the air which makes the lower lung develop a positive pressure
- therefore when you take a breath in from RV you will actually breathe into the upper lung first because it will still have an negative pressure
- the upper lung will be on the linear part of the P-V curve while the lower lung will be on the lower plateau |
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Term
| When patients with emphysema take a breathe does it fill the upper or lower part of the lung first? Why? |
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Definition
- patients with emphysema have a very big RV
- patients wil emphysema will always fill the top part of their lungs first
- however, there is still more blood in the bottom of the lung than in the top of the lung, so this will create even more of a V/Q mismatch |
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