Podcast
Questions and Answers
Which condition is associated with increased lung compliance?
Which condition is associated with increased lung compliance?
- Myositis
- Old age (correct)
- Kyphosis
- Obesity
What primarily contributes to the work of breathing during expiration?
What primarily contributes to the work of breathing during expiration?
- Passive elastic recoil of the lungs (correct)
- Increased airway resistance
- Compliance changes in the thorax
- Active muscular contraction
Which of the following factors decreases lung compliance?
Which of the following factors decreases lung compliance?
- Athletic training
- Emphysema
- Scoliosis (correct)
- Increased surface tension
What percentage of total body energy expenditure does the work of breathing account for at rest?
What percentage of total body energy expenditure does the work of breathing account for at rest?
Which work of breathing is defined as the effort to expand the lung against its elastic recoil?
Which work of breathing is defined as the effort to expand the lung against its elastic recoil?
What is the primary effect of bronchodilation on airflow resistance?
What is the primary effect of bronchodilation on airflow resistance?
Which system primarily mediates bronchoconstriction in the respiratory system?
Which system primarily mediates bronchoconstriction in the respiratory system?
What does the term 'compliance' refer to in pulmonary mechanics?
What does the term 'compliance' refer to in pulmonary mechanics?
Which of the following factors is known to decrease lung compliance?
Which of the following factors is known to decrease lung compliance?
How does increased work of breathing typically manifest?
How does increased work of breathing typically manifest?
What physiological changes occur in compliance with aging?
What physiological changes occur in compliance with aging?
Which receptors are primarily involved in bronchial muscle contraction during bronchoconstriction?
Which receptors are primarily involved in bronchial muscle contraction during bronchoconstriction?
What is the primary role of surfactant in the lungs?
What is the primary role of surfactant in the lungs?
What is the definition of pulmonary compliance?
What is the definition of pulmonary compliance?
What is the normal value for lung compliance?
What is the normal value for lung compliance?
Which of the following factors does NOT affect lung compliance?
Which of the following factors does NOT affect lung compliance?
In which type of lung condition is lung compliance typically decreased?
In which type of lung condition is lung compliance typically decreased?
What is the formula for lung compliance?
What is the formula for lung compliance?
How does surface tension in the alveoli affect lung compliance?
How does surface tension in the alveoli affect lung compliance?
During which part of the breathing cycle is decreased surface tension likely to increase lung compliance?
During which part of the breathing cycle is decreased surface tension likely to increase lung compliance?
What does the hysteresis loop in the dynamic lung pressure-volume curve indicate?
What does the hysteresis loop in the dynamic lung pressure-volume curve indicate?
Flashcards
Lung Compliance
Lung Compliance
Ability of the lungs to expand and contract during breathing.
Reduced Lung Compliance
Reduced Lung Compliance
Lungs expand less easily, requiring more effort for breathing.
Work of Breathing
Work of Breathing
Effort respiratory muscles use to move air in and out of lungs.
Compliance Work
Compliance Work
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Components of Breathing Work
Components of Breathing Work
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Bronchodilation
Bronchodilation
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Bronchoconstriction
Bronchoconstriction
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Factors Affecting Airway Diameter
Factors Affecting Airway Diameter
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Sympathetic Nervous System Impact
Sympathetic Nervous System Impact
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Parasympathetic Nervous System Impact
Parasympathetic Nervous System Impact
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Compliance
Compliance
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Decreased Compliance
Decreased Compliance
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Increased Compliance
Increased Compliance
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Lung Compliance: What is it?
Lung Compliance: What is it?
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Compliance Formula
Compliance Formula
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Normal Compliance Values
Normal Compliance Values
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What affects Lung Compliance?
What affects Lung Compliance?
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Compliance in Restrictive Lung Diseases
Compliance in Restrictive Lung Diseases
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Dynamic vs. Static Compliance
Dynamic vs. Static Compliance
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Hysteresis Loop
Hysteresis Loop
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Study Notes
Pulmonary Compliance and Work of Breathing
- Pulmonary compliance is the change in lung volume per unit pressure change.
- Normal lung compliance for the lungs alone is 200 ml/cm H2O.
- Normal lung and chest wall compliance combined is 100 ml/cm H2O.
- Compliance is lower during deflation than inflation, this is called hysteresis.
- Factors decreasing compliance include: decreased surfactant, pulmonary congestion, pulmonary fibrosis, pulmonary edema, and chest wall issues (e.g., kyphosis, scoliosis, obesity).
- Factors increasing compliance include old age and emphysema.
Work of Breathing
- Work of breathing is the effort needed to overcome resistance to move air in and out of the lungs.
- During normal breathing, work is primarily done during inspiration. Exhalation is passive.
- At rest, work of breathing represents 1-2% of total body energy.
- During heavy exercise, work of breathing represents 3-5% of total body energy.
- Work of breathing can be divided into three parts: compliance work, tissue resistance work and airway resistance work.
- Compliance work is 65% of the total work of breathing and is required to expand the lungs against their elastic recoil tendency.
- Tissue resistance work is 7% of the total work of breathing and is required to overcome the resistance of non-elastic lung and chest wall tissue components.
- Airway resistance work is 28% of the total work of breathing and is required to overcome resistance to airflow during breathing.
Factors Affecting Airway Resistance
- Airway resistance is inversely proportional to the fourth power of the radius. Thus a decrease in radius significantly increases airway resistance.
- Airway resistance is inversely proportional to the number of airways. Thus an increase in the number of airways decreases airway resistance.
- Larger airways (e.g., medium sized bronchi) have higher resistance compared to smaller ones (e.g., terminal bronchioles) due to having a smaller radius and a lower number of airways.
- Factors affecting airway resistance include lung volume, airway radius, and airway number.
Factors Affecting Bronchial Diameter
- Bronchodilation (decreased resistance):
- Sympathetic nervous system (releases noradrenaline) acting on beta-2 adrenergic receptors.
- Adrenaline from adrenal medulla acting on beta-2 adrenergic receptors.
- Bronchoconstriction (increased resistance):
- Parasympathetic nervous system (releases acetylcholine) acting on muscarinic receptors.
- Histamine, Leukotrienes, Cold air, increased PCO2, and dust/gas irritation.
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