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69 Cards in this Set
- Front
- Back
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Conducting zone
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-Larger airway
-Does NOT participate in gas exchange -Warms and humidifies air -Evenly distributes air in deeper sections of lung -Trap toxins, dust, bacteria |
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Respiratory zone
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Alveoli - gas exchange
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Describe alveoli
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Thin walls and large surface area - air-blood barrier
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Sequence of events in inspiration
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Inspiratory muscles contract (diaphragm drops, rib cage rises) --> thoracic volume increases --> lungs stretched --> intrapulmonary pressure drops to negative --> air rushes into lungs down pressure gradient until pressure is 0 again
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Sequence of events in expiration
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Inspiratory muscles relax (diaphragm rises, rib cage descends due to gravity) --> thoracic volume decreases --> elastic lungs recoil passively --> intrapulmonary pressure rises to positive --> air rushes out until pressure is 0 again
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Pleural pressure
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-pressure in the pleural space
-negative at rest due to opposing forces of chest wall and lung - chest wall wants to go out, lungs want to come in (collapse), this negative pressure keeps lungs from collapsing |
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Alveolar pressure
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Pressure inside alveoli
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Transmural pressure
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2 parts:
-Transpulmonary - difference between alveolar and pleural pressures, lungs will not collapse as long as this pressure is positive -Transairway- difference between airway and pleural pressures, keeps airways open during forced expiration |
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Describe pressures at rest
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At rest alveolar pressure = barometric pressure = 0
Pleural pressure is NEGATIVE, transpulmonary pressure is POSITIVE Pleural and transpulmonary pressures exert equal and opposite forces, chest wall has potential to recoil outward and lungs have potential to recoil inward |
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Describe pressures during inspiration
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Alveolar pressure is less then barometric pressure
Pleural pressure becomes more negative and transpulmonary pressure becomes more positive As thoracic volume increases, alveolar pressure becomes negative, creating a pressure gradient. Pleural pressure becomes more negative as a result of increase in thoracic volume and force of elastic lung recoil |
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Describe pressures during expiration
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Alveolar pressure is greater then barometric pressure
Alveolar pressure becomes positive because forces pushing for lung recoil compress air in alveoli.When alveolar pressure becomes greater then barometric, pressure gradient is created and air rushes out of the lung. As thoracic volume decreases, pleural pressure becomes less negative and transpulmonary pressure becomes more positive |
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Describe pressures during forced expiration
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Alveolar pressure is twice as much as barometric. Both pleural and transpulmonary pressures become positive due to contraction of expiration muscles. Greater pressure in alveoli compared to barometric creates a large pressure gradient resulting in rapid and forceful expiration
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What happens in pneumothorax
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Puncture wound lets air in the pleural space and pleural and transpulmonary pressures become 0. Without these pressures lungs collapse and chest goes outward.
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Tidal volume
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Normal breathing
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Inspiratory reserve volume
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Max amount of air that can be inhaled after normal inspiration
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Expiratory reserve volume
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Max amount of air that can be exhaled at the end of tidal volume
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Residual volume
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Volume of air remaining in lungs after maximum expiration - CAN NOT BE MEASURED WITH SPIROMETRY
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Inspiratory capacity
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Max amount of air inhaled following normal expiration - from lower end of tidal volume and up
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Functional residual capacity
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CAN NOT BE MEASURED WITH SPIROMETRY
-amount of air remaining in lungs at the end of tidal volume |
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Vital capacity
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Everything except residual volume - max amount of air that can be exhaled
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Total lung capacity
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amount of air in lungs following max inspiration
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Vital capacity is sum of _
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Tidal volume + expiratory reserve volume + inspiratory reserve volume
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Inspiratory capacity is sum of _
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Tidal volume and inspiratory reserve volume
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Functional residual capacity is sum of _
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Expiratory reserve volume and residual volume
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Total lung capacity is the sum of _
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4 volumes - tidal volume + inspiratory reserve volume + expiratory reserve volume + residual volume
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Forced expiratory volume
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amount of air that can be forcibly expired per unit time ( 1-3 sec)
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Forced vital capacity
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Amount of air that can be forcibly expired following maximum inspiration
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What ratio is used to differentiate lung diseases
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FEV/FRC
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Obstructive lung disorders
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Obstruction of small airways
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Restrictive lung disorders
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Reduced compliance of lung or chest wall or weakening of inspiratory muscles
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Normal vs patient with obstructive disorder
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Obstructive disorders include asthma and emphysema and are characterized by slow air movement during forced expiration.
FEV1 will be greatly reduced FVC will be also reduced Residual volume will be increased since a lot of air is left and cannot get out. FEV1/FVC ration would be decresed drastically |
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Normal vs patient with restrictive disorder
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Restrictive disorders are disorders like lung fibrosis that reduce lung compliance.
Maximum inspiratory volume and vital capacity will be reduced. Amount of air exhaled will be reduced since air inhaled is also reduced FEV1/FVC ratio will be slightly increased compared to normal patient |
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Define anatomical dead space
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Part of airway where air fills lungs but doesnt contribute to gas exchange
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Define alveolar dead space
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Normally not present but if alveoli stop participating in gas exchange due to collapse, blockage or reduced blood flow, you get alveolar dead space
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Define physiological dead space
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Physiological dead space = anatomical dead space + alveolar dead space
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Alveolar ventilation rate
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Va = breaths per min (f) * (tidal volume - dead space)
Dead space = anatomical dead space + alveolar dead space In normal lungs, dead space = anatomical dead space |
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Minute ventilation
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Breaths per min (f) * tidal volume - total amount of air inspired per min
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What happens to alveolar ventilation rate when patient is hyperventilating
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Becomes 0
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What happens to alveolar ventilation rate when patient is hypoventilating
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Increases
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Define distensibility of lung
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Ease lung is stretched/inflated
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Increasing distensibility decreases _
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Elastic recoil of the lung
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_ is measure of distensibility
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Compliance
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Conditions with increased lung compliance
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Infection, COPD, environmental toxins
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Conditions with decreased lung compliance
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Restrictive - fibrosis
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About 2/3 of work required to inflate lung is due to _
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Surface tension
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Surface tension decreases _
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Alveoli diameter and surface area - producing inward force and collapsing pressure
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Collapsing pressure is directly proportional to _ and inversely proportional to _
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Directly proportional to surface tension and inversely proportional to radius
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Surfactant
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-Allows alveoli of different sizes to coexist and be stable at lower lungs volumes
-Also increases lung compliance so decreases work needed for inflation of the lungs -Lower surface tension |
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Main cause of neonatal respiratory distress
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Lack of surfactant
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Airflow equals to
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Pressure /Resistance
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Major site of resistance in lungs
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Medium bronchi
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Factor affecting airway resistance
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- Lung volume - decrease volume - increase resistance
-Smooth muscle tone - sympathetic - bronchial dilation, parasympathetic - bronchial constriction -Gas density - deep sea diving |
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Difference between partial pressure of O2 in lungs and atmospheric air
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When you figuring out partial pressure in lung need to subtract partial pressure of water vapor
Px = (Pb- Ph2o) * F |
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Driving force for diffusion in lungs
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Difference in partial pressures across membrane
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Emphysema
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Decrease functioning alveoli, decreases surface area
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Fibrosis
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Increases membrane thickness
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Exercise
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Increases capillary perfusion so increases surface area
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3 forms of gases in solution
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1) Dissolved
2)Bound - O2, CO2, CO bound to hemoglobin 3)Chemically modified - CO2 travels as bicarbonate |
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Which gases contribute to partial pressures
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DISSOLVED ONLY
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Alveolar perfusion and ventilation are highest at _ , lowest at _
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Highest at base, lowest at apex
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V/Q (ventillation/perfusion) ration is higher at _ , lower at _
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Higher at apex, lower at base
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You get overventilation at _
and overperfusion at _ |
Overventilation - apex
Overperfusion - base |
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Venous admixture
2 causes |
Mixture of oxygenated and deoxygenated blood
1) physiological shunt - small amount of blood that doesnt participate in gas exchange and leaves pulmonary capillaries unoxygenated - 1 % of CO 2)low V/Q ratio - insufficient alveolar ventilation |
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If partial pressure limits exchange it _ , if blood flow its _
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Diffusion limited - CO
Perfusion limited - N2O |
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2 types of O2 transport
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1) Dissolved
2) Bound to Hb - 98% |
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Shift to left in Hb curve means _ , right _
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Left - increased affinity - makes unloading at tissues more difficult
Right - decreased affinity - unloading of O2 at tissues |
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Factors that can cause right shift in Hb curve
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1) acidosis - Bohr effect
2)increase temp 3) increase 2,3 - BPG |
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Factors that cause left shift in Hb curve
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1) alkalosis
2)decrease temp 3) decrease 2,3 BPG |
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3 transport mechanisms of CO2
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1) dissolved
2)bound to hemoglobin 3) as bicarbonate |
