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35 Cards in this Set
- Front
- Back
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roles of respiratory system
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1. large particle filtered out of the nose
2. small particles removed by mucus 3. particle deposited in alveoli engulfed by macrophages and removed by lymphatics or blood flow 4. gas exchange 5. metabolism of compounds 6. filtering of unwanted materials from the circulation 7. serves as a reservoir for blood |
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bronchial anatomy
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-trachea (series of cartilaginous ringS)
-right and left mainstem -primary, secondary, tertiary bronchi -terminal bronchioles -respiratory bronchiole (gas exchange) -alveoli (sacs of air surrounded bya network of blood vessels) |
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FRC
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-functional residual capacity
-vol in lungs at the end of normal expiration -lungs if left alone collapse -chest wall has a resting vol, have a tendency to pull out -lungs and chest wall generally function as a single unit and give you your FRC |
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TV
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-tidal volume
-normal, quiet breathing |
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IRV
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-inspiratory reserve vol
-the extra burst of air you get with deep inhalation |
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ERV
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-expiratory reserve vol.
-the additional amt you can breathe out with forced exhalation |
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RV
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-residual vol
-air that cannot be moved out, even with deep breaths |
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intrapleural pressure
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-area outside the lung but withint the chest wall
-negative at rest -"balancing" of forces -this is lost with any holes in the system (pneumothorax-the pressure differential is lost and the lung collapses with the thorax pushing out) |
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Breathing lung volume
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-increasing lung vol above FRC requires work (active)
-inspiratory muscles stretch chest wall -pleural P falls -lungs are stretched |
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recoil P of the lung
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-lung has to be stretched
-normally very elastic and flexible -increased collagen stiffens lung -fluid, blood or pus in the lung also makes it smaller and stiffer (PNA, CHF, hemorrhage) -air/fluid interface is harder to inflate -surfactant- lowers surface tension |
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breathing
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-once lung is inhaled, it requires ongoing forces to overcome lung elastic recoil forces
-when inspiratory muscle relax, there is passive deflation back to FRC -can use expiratory m. for active deflation |
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High FRC
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-low recoil pressure- tendency to collapse is slightly hindered (emphysema)
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Low FRC
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-high recoil pressure- lung has a tendency to recoil even faster (lung fibrosis)
-abnl chest wall |
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low lung volumes (restriction)
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P: pleural
L: lung diseases A: abdominal diseases N: neuromuscular diseases T: thoracic diseases |
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Airflow
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-flow through tubes requires force to overcome resistance
-resistance depends on: 1. size of the airway- airway diameter 2. flow characteristics: turbulant vs. laminar 3. gas properties: air vs. helium 4. airflow rates |
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flow rates controlled by
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-resistance
-expiratory forces: lung recoil P, chest wall recoil P, expiratory muscle activity -higher flow rates at large lung vol -lower effort yields lower flow rates |
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dynamic compression of the airways
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-expiratory forces will compress the airway, limiting the ability to force higher airflow
-Seen with forced expiration- both intrapleural and alveolar pressure increase by same amount. But, as flow begins, pressure in the airways starts to drop. At some point, there is a net effect of compression on the airways |
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airways diseases limit flow rates...
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1. Bronchitis/Asthma- airways are small (constricted), plugged (mucous) or edemetaous
2. Emphysema- airways are nml, but lung recoil P is low and airways are floppy; lung lost elastic properties |
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Obstruction
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-scooped flow rates
-FVC- maximal amt of air that can be exhaled -FEV1- amt of air exhaled in first second -FEV1/FVC 80%- nml -FEV1/FVC <70%- obstructed |
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upper airway obstruction
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-variable extrathoracic obstruction
-upper airway obstruction flattens the curve because maximal flow is limited (Both inspiratory and expiratory curves are flattened with fixed upper airway obstruction (eg. glottic or tracheal stenosis and tracheal narrowing due to tumor) |
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high airway resistance- obstruction
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-increased work of breathing: fatigue, dyspnea
-"dynamic hyperinflation" with attempts to breathe quickly -tendency to trap air; an inability to fully breathe out all of their air before the next breath is taken in. This causes a progressive increase in FRC -ex. emphysema, asthma with an acute flare |
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ventilation and oxygenation
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1. removal of CO2
2. movement of air (i.e. oxygen) into the venous blood |
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ventilation
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-primary control of breathing is maintaining normal ventilation, i.e. PaCO2 = 40
-hyperventilation - breathing too much, low CO2 -hypoventilation - breathing too little, high CO2 -CO2 leaves the blood and enters the alveolus, reaching full equilibrium very quickly |
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dead space ventilation
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-not all air entering mouth gets into alveolus and not all alveoli have blood flow
-this ventilation is considered "wasted" or "deadspace" |
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gas exchange: CO2
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-CO2 level in blood is dependent upon: amt of fresh air delivered to alveoli with adequate blood supply
-amt of COA production in the basal state and with exercise |
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hyperventilation
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-appropriate: compensatory- metabolic acidosis, altitude, exercise
-abnormal: lung disease, neurologic disease, illness, pain, anxiety, psychiatric |
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hypoventilation
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-can't breath: neuromuscular weakness, chest wall diseases, parenchymal diseases, airways diseases
-won't breath: drugs, brainstem diseases, idiopathic (obese-Pickwickian) |
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Hypercapneic respiratory failure
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-high CO2 levels
-acute: no time for renal compensation, pH severely reduced -chronic: >48 hrs, renal compensation protect pH -consider ventilatory support- endotrachial tube, BiPAP |
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oxygenation
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-normally, ventilation gives adequate oxygenation
-if oxygenation is impaired --> hypeventilate -O2 equilibrates slower than CO2 -look at pic! |
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hypoxemia
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-5 causes
1. hypoxia- Low PAO2 2. hypoventilation- low O2 in alveolus 3. Shunt 4. V/Q mismatch 5. Diffusion |
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Shunt
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-blood enters alveoli without any ventilation or bypass lung entirely
-blood not getting oxygenated -do NOT respond to O2 -causes include cardiac vs. pul vs. other |
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Ventilation/perfusion mismatch
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-ventilation and perfusion higher at base of lunch
-blood flow past alveoli that are not well ventilated -area of low V/Q ratio will have incompletely oxgenated blood, with resultant decreased O2 level in the arterial blood -->corrected with giving O2 -area of high V/Q will have inadequate blood floe and therefore not participate in gas exchange |
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ventilation-perfusion summary
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-high V/ Low Q = dead space
-low V/ high Q = V/Q mismathc -no V/high Q = shunt |
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Diffusion limitation
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-blood flows so fast past the alveoli that there is insuficient time to equilibate fully
-requires: slow diffusion, fast blood flow |
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Gas Exchange: V/Q Mismatch vs. Diffusion Limitation
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Blood goes past alveoli, but
V/Q mismatch: air is not “fresh” and has a low oxygen tension Diffusion limitation: blood flowing too fast or oxygen “moving” too slow (via thickened membrane) Can’t easily separate these two clinically Both improve with supplemental oxygen |
