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Questions and Answers
What role does surfactant play in preventing pulmonary edema?
What role does surfactant play in preventing pulmonary edema?
- Increasing the filtration forces in the alveoli.
- Decreasing the filtration forces in the alveoli. (correct)
- Maintaining a high surface tension to draw fluid back into the capillaries.
- Promoting fluid accumulation in the interstitial space.
A patient with pulmonary fibrosis exhibits decreased lung compliance. How does this condition affect the work of breathing?
A patient with pulmonary fibrosis exhibits decreased lung compliance. How does this condition affect the work of breathing?
- Decreased compliance only affects expiration, not inspiration.
- Decreased compliance increases the work of breathing as more effort is required to expand the lungs. (correct)
- Decreased compliance has no impact on the work of breathing.
- Decreased compliance reduces the work of breathing due to increased lung volume.
According to the relationship between pressure, flow, and resistance, if a patient experiences increased airflow resistance due to bronchoconstriction, what compensatory mechanism must occur to maintain adequate airflow?
According to the relationship between pressure, flow, and resistance, if a patient experiences increased airflow resistance due to bronchoconstriction, what compensatory mechanism must occur to maintain adequate airflow?
- Decrease in the pressure gradient.
- Increase in the elasticity of the lungs.
- Increase in the pressure gradient. (correct)
- Decrease in the radius of the airways.
A premature infant is diagnosed with hyaline membrane disease due to a deficiency in surfactant. Which of the following physiological consequences is most likely to occur?
A premature infant is diagnosed with hyaline membrane disease due to a deficiency in surfactant. Which of the following physiological consequences is most likely to occur?
How does stimulation of the parasympathetic nervous system affect airflow resistance in the lungs?
How does stimulation of the parasympathetic nervous system affect airflow resistance in the lungs?
Emphysema is characterized by increased lung compliance. Which of the following is most likely to occur as a direct result of this increased compliance?
Emphysema is characterized by increased lung compliance. Which of the following is most likely to occur as a direct result of this increased compliance?
A patient's pulmonary function test reveals a decreased ratio of change in volume to change in pressure ($\frac{\Delta V}{\Delta P}$). What does this indicate about the patient's respiratory condition?
A patient's pulmonary function test reveals a decreased ratio of change in volume to change in pressure ($\frac{\Delta V}{\Delta P}$). What does this indicate about the patient's respiratory condition?
Albuterol, a β2-agonist, is administered to a patient experiencing an asthma attack. If this treatment results in a doubling of the airway diameter, by what factor does the airway resistance change, assuming that resistance is inversely proportional to the fourth power of the radius?
Albuterol, a β2-agonist, is administered to a patient experiencing an asthma attack. If this treatment results in a doubling of the airway diameter, by what factor does the airway resistance change, assuming that resistance is inversely proportional to the fourth power of the radius?
Flashcards
Surfactant
Surfactant
A mixture of phospholipids and calcium secreted by alveolar type II cells, reducing surface tension in alveoli.
Function of surfactant
Function of surfactant
Prevents pulmonary edema, alveolar collapse during expiration, and decreases the work of breathing.
Pulmonary Compliance
Pulmonary Compliance
Measures the distensibility and expansibility of the lungs and thorax, calculated as C = ∆V/∆P.
Hysteresis
Hysteresis
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Bronchodilation
Bronchodilation
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Bronchoconstriction
Bronchoconstriction
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Airflow Resistance
Airflow Resistance
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Factors affecting compliance
Factors affecting compliance
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Study Notes
Mechanics of Respiration II: Alveolar Cells
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Type I Pneumocytes:
- Squamous, extremely thin cells
- Cover ~95% of alveolar surface
- Crucial for gas exchange
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Type II Pneumocytes:
- Granular, roughly cuboidal cells
- Cover ~5% of alveolar surface
- Secrete pulmonary surfactant
Pulmonary Surfactant
- A mixture of phospholipids and proteins
- Secreted by Type II alveolar cells
- Reduces surface tension in alveoli
- Prevents alveolar collapse during exhalation
- Decreases the work of breathing
- Function to decrease the filtration forces thus preventing pulmonary edema
Surface Tension
- Force exerted by fluid within alveoli to resist expansion
- This is important to the function of the lungs to be able to maintain the thin film of fluid without collapsing
- Lungs secrete and absorb fluid, maintaining a thin fluid film
- This film causes surface tension
Pulmonary Compliance
- Overall distensibility and expansibility of the lungs and thorax
- Compliance (C) = Change in volume (ΔV) / Change in pressure (ΔP)
- Pulmonary compliance can be affected by factors such as increased (emphysema) or decreased (edema, fibrosis, congestion) lung conditions
Hysteresis
- Compliance is greater during expiration than inspiration
- This is a significant factor in respiration
Conditions Affecting Compliance
- Conditions like emphysema can increase compliance
- Conditions such as pulmonary fibrosis, edema, or congestion can decrease compliance
Sympathetic Nervous System
- Causes relaxation of bronchial smooth muscles (bronchodilation)
Parasympathetic Nervous System
- Causes contraction of bronchial smooth muscles (bronchoconstriction)
- Increases mucus secretion
Airflow Resistance
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Resistance produced for airflow during breathing
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Flow = ΔP/R
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R = 8ηL / πr⁴
- Where η is fluid viscosity, L is the tube length, and r is the tube radius.
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Bronchodilation increases the radius and decreases resistance.
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Bronchoconstriction decreases the radius and increases resistance as a result of conditions such as asthma, pneumonia, and fibrosis.
Function of Surfactant (Summary)
- Prevents pulmonary edema by decreasing the filtration forces
- Prevents collapse of alveoli during exhalation
- Decreases the work of breathing
Deficiency of Surfactant
- Causes hyaline membrane disease or respiratory distress syndrome
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Description
Exploration of Type I and Type II pneumocytes, crucial for gas exchange and surfactant secretion in the alveoli. Discussion on pulmonary surfactant's role in reducing surface tension and preventing alveolar collapse. Overview of surface tension and pulmonary compliance relating to lung function.
