Term
| Are the pressures in the pleural space negative or positive and why? |
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Definition
| The pressures are negative relative to atmospheric pressure because of two opposing forces: outward recoil of the thorax and the lung's inward elastic recoil |
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Term
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Definition
| When the chest wall and parietal pleura are punctured the stretched lung will immediately collapse and the thorax will immediately expand outward; the pressure in the pleural space will become equal to atmospheric pressure |
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Term
| Which airways do not have cartilage and are prone to collapse? |
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Definition
| The bronchioles and respiratory bronchioles |
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Term
| Does expiration usually require work by the muscles of respiration? |
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Definition
| No, only with exercise or forced expiration |
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Term
| With inspiration, the pleural pressure becomes more negative or positive? |
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Definition
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Term
| What determines alveolar pressure? |
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Definition
| The pressure within the alveolus is the sum of the forces acting upon it, elastic recoil and pleural pressure |
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Term
| When is thoracic elastic recoil greatest? |
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Definition
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Term
| When is lung elastic recoil greatest? |
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Definition
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Term
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Definition
| change in volume / change in pressure |
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Term
| What is static compliance? |
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Definition
| The volume change per unit of pressure under conditions of no airflow |
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Term
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Definition
Airway closure and trapping of air during expiration; It takes a greater pressure to open alveoli that have collapsed at small lung volumes than it does to keep them open
On a pressure vs volume graph, there will be a larger lung volume at any given pressure during deflation as opposed to inflation |
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Term
| Residual volume is usually what percent of TLC? |
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Definition
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Term
| How does lung volume affect compliance? |
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Definition
| Compliance is high at low lung volumes and low at high lung volumes |
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Term
| How do you calculate specific compliance? |
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Definition
Specific compliance = Cl/Liter of lung volume
Since larger lungs have higher compliance, compliance should be corrected for lung size |
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Term
| What effect does surfactant have on surface tension? |
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Definition
It decreases surface tension; so does detergent or saline solution
Surfactant reduces the surface tension forces at the gas-liquid interface, stabilizing smaller alveoli |
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Term
| When is surface tension recoil high? |
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Definition
| Surface tension recoil is high when the lung volume is high (inflated) and low when lung volume is low (deflated) |
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Term
| What produces surfactant and when is it produced? |
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Definition
| Surfactant is produced by type II alveolar pneumocytes and secreted into the alveolar space during a deep breath |
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Term
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Definition
| The volume of gas inspired during each quiet spontaneous breath |
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Term
| What is inspiratory reserve volume (IRV)? |
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Definition
| The maximum volume of gas that can be inspired following a normal tidal volume inspiration |
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Term
| What is expiratory reserve volume (ERV)? |
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Definition
| The maximal volume of gas that can be expired following a normal tidal volume |
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Term
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Definition
| The volume of gas remaining in the lungs following a maximal expiration; about 20% of TLC; both increases (emphysema) and decreases (asthma) in compliance will increase RV; |
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Term
| What is vital capacity (VC)? |
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Definition
| The maximal amount of gas that can be forcefully expelled from the lungs following a maximal inspiration |
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Term
| What is functional residual capacity? |
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Definition
| The volume of gas remaining in the lung at the resting expiratory position following a tidal breath; At this point, alveolar pressure is equal to atmospheric pressure |
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Term
| What is inspiratory capacity (IC)? |
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Definition
| The maximal amount of gas that can be inspired from the resting expiratory level following at tidal breath |
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Term
| What is forced vital capacity (FVC)? |
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Definition
The volume exhaled from TLC to RV; in a normal individual, FVC = VC
The normal FVC for an average sized adult is 5L |
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Term
| What is Forced Expiratory Volume in One Second (FEV1)? |
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Definition
| The volume of air exhaled from TLC to RV in the first second; A patient with normal lung function can forcefully exhale ~80% of their VC in the first second |
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Term
| What is the ratio of FEV1/FVC useful in diagnosing? |
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Definition
| Patients with a combination of obstructive and restrictive lung disease |
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Term
| What is Forced Mid-Expiratory Flow (FEF25-75)? |
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Definition
| The expiratory flow over the mid portion of the FVC (25%-75% of FVC); has the greatest sensitivity of all measurements made by the forced expiratory maneuver for detecting early airflow obstruction |
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Term
| What can be accurately measured by a flow-volume loop? |
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Definition
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Term
| What volumes can not be measured by spirometry? |
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Definition
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Term
| What is the equal pressure point? |
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Definition
| Point when pressures inside the airway and outside the airway are equal |
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Term
| How does a decrease in compliance and an increase in recoil (restrictive lung disease) affect TLC, RV, FEV1, and FVC? |
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Definition
It reduces all of them
Airflows are also reduced, but in proportion to the reduction in lung volume |
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Term
| What factors are indicative of restrictive lung disease? |
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Definition
Reduced lung volume: FVC is < 80%, FEV1 is reduced but proportional to the reduction in FVC, FEV1/FVC ration is normal
Reduced expiratory flow: FEF25-75 is decreased in proportion to the reduction in lung volumes; the ratio of percent predicted FEF25-75/% predicted FVC > 0.8 diagnoses a restriction to ventilation, not an obstruction to ventilation |
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Term
| What are the characteristics of restrictive ventilation defects? |
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Definition
Reduced compliance of lung parenchyma and/or reduced compliance of the thorax
examples are interstitial fibrosis, interstitial edema, and pneumonia |
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Term
| What are the characteristics of obstructive ventilation defects? |
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Definition
Increased large airway resistance, increased small airway resistance, destroyed small airways, or destroyed lung elastic tissue
examples are asthma, chronic bronchitis, and emphysema |
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Term
| What laboratory factors are indicative of obstructive lung disease? |
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Definition
| A reduced FEV1/FVC ratio and a reduced FEF25-75 |
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Term
| How is the FEV1/FVC ratio used to characterize the severity of airway obstruction? |
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Definition
Mild airway obstruction ratio is 75%-65%
Moderate airway obstruction ratio is 65%-55%
Severe airway obstruction ratio is <55% |
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Term
| What is Poiseuille's law and what is it used for? |
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Definition
R = (8 x u x L) / (pi x r^4)
Determines airway resistance to both the diameter of the airways and the total cross sectional area of the airways |
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Term
| Before small airways will have an effect on total airway resistance, how much of a reduction must their be in the cross sectional area of the small airways? |
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Definition
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Term
| What effects maximum expiratory flow (Vmax)? |
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Definition
| Lung elastic recoil is directly proportional while upstream resistance is inversely proportional |
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Term
| What types of breath will be present in restrictive lung disease? |
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Definition
| Patients with restrictive lung disease will minimize their work of breathing by taking smaller tidal volumes and breathing more rapidly; their is an increased work in inspiration |
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Term
| What types of breaths will be present in obstructive lung disease? |
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Definition
| Patients adopt a slower, deeper pattern of breathing; there is an increase in both the work of inspiration and expiration |
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