Term
| How many alveoli are in each lung? |
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Definition
| There are 150 - 200 million alveoli in each lung. Thus 300 - 400 million total. |
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Term
| T/F: The natural tendency of the lungs is to expand outward due to force caused by elastic tissues. |
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Definition
| False. The elastic tissues cause the lungs to have a natural inward force. |
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Term
| What keeps the visceral and parietal pleura together? |
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Definition
| The cohesive forces created by pleural fluid between the two. |
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Term
| What causes the negative pressure in the plural space? |
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Definition
1. Outward recoil of the thorax
2. Inward elasic coil of the lungs |
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Term
| How many of the first generations of the airways are surrounded by cartilage? |
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Definition
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Term
| What are the accessory muscles of respiration? |
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Definition
| External intercostal muscles, internal and middle scalene, SCM. All are used to create a forced inspiration. |
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Term
| T/F: Inspiration is a passive event, while expiration requires energy. |
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Definition
| False. Inspiration requires energy while normal expiration is a passive event. |
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Term
| What additional force must be overcome during respiration with regard to the airways? |
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Definition
| Resistance, which increases the amount of force necessary during respiration. |
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Term
| How much does intrapleural pressure change during quiet tidal breathing? |
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Definition
| 2.5 cm H2O and alveolar pressure changes only 1 cm H2O. |
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Term
| What is Pulmonary Elastic Recoil? |
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Definition
| This is the elastic recoil that is generated by the elastic tissue in the lungs, which unopposed would force air out of the alveolus and cause the lungs to collapse. |
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Term
1. What happens to intrapleural pressure during quiet expiration?
2. During forced expiration? |
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Definition
1. It becomes less negative
2. It becomes positive, with the degree depending on the force of expiration. |
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Term
| What is alveolar pressure (Palv)? |
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Definition
This is the pressure in the alveolus which is the sum of the forces acting upon it, elastic recoil and pleural pressure.
Equation: Palv = Pel + Ppl |
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Term
| How much of a pressure differential is necessary in order to have airflow in the lungs? |
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Definition
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Term
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Definition
| This occurs when increased airway resistance causes pressure along the airway to decrease. Airway pressure downstream from this will become negative which will collapse the lumen trapping air behind it. |
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Term
| What is embedded into the elastic connective tissue in the lungs? |
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Definition
| Alveoli, airways, and pulmonary vasculature |
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Term
T/F:
1. Loss of Elastin will allow the lungs to become more distensible.
2. Increased collagen will make the lungs less distensible. |
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Definition
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Term
| At what point does the elastic properties of the thorax stop increasing the lung size? |
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Definition
| At 75% TLC the elastic properties of the thorax cease to have an effect on lung size, and will begin to decrease thoracic volume. Thus, over most lung sizes, the elastic properties of the thorax act to increase size. |
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Term
1. At what point is the elastic properties of the thorax the greatest?
2. At what point is the elastic property of the lungs the greatest? |
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Definition
1. At Residual Volume
2. At Total Lung Capacity |
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Term
| What is the equation for lung compliance? |
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Definition
|
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Term
| What is hysteresis in lungs and what causes it? |
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Definition
| Hysteresis is the inherent characteristic of the lung to have different volumes at identical pressures for inspiration and expiration. It is caused by airway trapping and the face that is takes a greater pressure to open collapsed airways |
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Term
| T/F: Volume during deflation will be larger than volume during inspiration at identical pressure. |
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Definition
| True. This is the property of hysteresis. There is airway closure and trapping during expiration which keeps lung volumes larger. |
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Term
| T/F: Patients with emphysema have increased compliance and increased lung volumes. |
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Definition
| True. The destruction of elastic tissue leads to these characteristics. |
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Term
| What is restrictive lung disease? |
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Definition
| This is when lungs are subject to interstitial fibrosis causing decreased compliance and increased elastic recoil. |
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Term
| T/F: Compliance is higher in small lung sizes and higher volumes. |
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Definition
| False. Compliance is higher in large sized lungs and low lung volumes. |
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Term
| What is the effect of surface tension on alveoli? |
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Definition
| The layer of water that covers the alveoli are attracted to humidified air and thus create tension that tries to reduce alveolar size. |
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Term
| The pressure necessary to maintain a given lung volume is the sum of what two forces? |
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Definition
| Elastic forces of pulmonary tissues and surface tension in the alveoli |
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Term
| What can be added to the alveoli in order to reduce surface tension? |
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Definition
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Term
| At what lung volumes is the effect of surfactant most effective? |
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Definition
| At lower volumes, surfactant has more ability to collect and exhibit more of an effect on surface tension. |
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Term
| What is the Laplace equation for surface tension in a sphere (alveolus)? |
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Definition
P =2T/r
P - Pressure
T - Surface Tension
r - Radius of sphere |
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Term
| How does surfactant act to prevent small airways and smaller alveoli from collapsing at low lung volumes? |
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Definition
| Surface tension is highest in smaller alveoli. However, surfactant has a greater effect on smaller alveoli which helps to maintain them from collapsing. This allows large and small alveoli to act in parallel. |
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Term
| Where is surfactant synthesized? |
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Definition
| Surfactant is synthesized in the Type II Pneumocytes in the alveoli and is secreted during deep breaths into the alveolar space. |
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Term
| T/F: Surfactant is readily spread during quiet inspiration. |
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Definition
| False. Deep breaths are necessary to spread surfactant. |
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Term
| What is the effect of impaired deep breathing on surfactant production? |
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Definition
| It will decrease the amount of surfactant produced, leading to atelectasis or alveolar collapse. |
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Term
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Definition
| Volume of gas remaining after a forced expiration. Normally is about 20% of TLC. |
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Term
| What is the effect of emphysema on RV? |
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Definition
With decreased elastic tissue, which decreases the ability of the lung to recoil and expire air, the RV will increase
. |
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Term
| What is Functional Residual Capacity? |
|
Definition
| The volume of air remaining in the lungs after a quiet expiration. |
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Term
| T/F: Patients with emphysema will have a TLC that is lower than 80% of predicted value. |
|
Definition
| False. Patients with emphysema have larger compliance and thus >120% of predicted TLC. |
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