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Lung Expansion and Pressure Changes
40 Questions
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Lung Expansion and Pressure Changes

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Questions and Answers

What happens to transpulmonary pressure at the end of inspiration?

  • It decreases below atmospheric pressure.
  • It fluctuates rapidly during gas exchange.
  • It increases to +9 cm H2O. (correct)
  • It remains constant throughout the respiratory cycle.

    • During expiration, what primarily causes the air to flow back into the atmosphere?

  • Increased volume in the thoracic cavity.
  • Expansion of the lung beyond functional residual capacity.
  • Contraction of the diaphragm in the relaxed state.
  • Compression of alveolar gases exceeding atmospheric pressure. (correct)

    • What is the primary characteristic of expiration during normal quiet breathing?

  • It is completely passive. (correct)
  • It requires the diaphragm to constantly contract.
  • It involves active muscle contraction.
  • It requires additional inhalation to assist.

    • What occurs at the end of inspiration regarding the diaphragm and intercostal muscles?

    <p>The muscles cease firing and relax.</p> Signup and view all the answers

    What role do internal intercostals play during forced expiration?

    <p>They contract to draw the ribs downward.</p> Signup and view all the answers

    Why is the transpulmonary pressure relatively constant during certain phases of the respiratory cycle?

    <p>Lung compliance is assumed to be unchanged.</p> Signup and view all the answers

    What happens to alveolar pressure during inspiration?

    <p>It drops below atmospheric pressure.</p> Signup and view all the answers

    How does lung volume change during expiration?

    <p>It decreases as thoracic volume reduces.</p> Signup and view all the answers

    What is the relationship between alveolar pressure and intrapleural pressure during a respiratory cycle?

    <p>Alveolar pressure is always greater than intrapleural pressure.</p> Signup and view all the answers

    How is compliance (C) of the lung defined?

    <p>The change in transpulmonary pressure required to achieve a change in lung volume.</p> Signup and view all the answers

    Which of the following correctly describes how lung compliance affects respiratory effort?

    <p>Higher compliance requires less effort to inflate the lung.</p> Signup and view all the answers

    What does a flatter compliance curve indicate?

    <p>Lungs become less compliant at higher pressures.</p> Signup and view all the answers

    What is the primary function of pulmonary ventilation?

    <p>To regulate blood pH through CO2 levels</p> Signup and view all the answers

    What does the change of 1 mm Hg in pressure equate to in cm H2O?

    <p>1.36 cm H2O</p> Signup and view all the answers

    Which of the following statements about the intrapleural space is correct?

    <p>It is filled with approximately 10-15 ml of intrapleural fluid.</p> Signup and view all the answers

    What does increased respiratory effort during inspiration indicate regarding lung compliance?

    <p>The lungs are less compliant than normal.</p> Signup and view all the answers

    What does the slope of the compliance curve represent?

    <p>The change in transpulmonary pressure per unit volume change.</p> Signup and view all the answers

    What effect does the diaphragm have during inspiration?

    <p>It contracts, increasing the volume of the thorax.</p> Signup and view all the answers

    What characterizes the functional residual capacity (FRC) of the lungs?

    <p>It is influenced by both the airways and the lung tissues.</p> Signup and view all the answers

    What happens to intrapleural pressure during lung inflation?

    <p>It decreases as the lung expands.</p> Signup and view all the answers

    Why is the pressure in the intrapleural space negative?

    <p>To keep the lungs inflated against the chest wall.</p> Signup and view all the answers

    What role does surfactant play in lung function?

    <p>It decreases the surface tension, aiding lung expansion.</p> Signup and view all the answers

    Which statement correctly differentiates between conducting zones and respiratory zones?

    <p>Conducting zones transport air, while respiratory zones facilitate gas exchange.</p> Signup and view all the answers

    Which of the following is NOT a factor influencing airway resistance?

    <p>Composition of surfactant</p> Signup and view all the answers

    What is the effect of a pneumothorax on the lung and thorax?

    <p>The lung collapses and the thorax expands.</p> Signup and view all the answers

    What does transpulmonary pressure (TPP) represent?

    <p>The difference between alveolar pressure and intrapleural pressure.</p> Signup and view all the answers

    What happens to intrapleural pressure during lung inspiration?

    <p>It decreases.</p> Signup and view all the answers

    What is the typical intrapleural pressure at functional residual capacity (FRC)?

    <p>-5 cm H2O</p> Signup and view all the answers

    How does aging affect the inward recoil of the lung tissue?

    <p>It decreases the inward recoil.</p> Signup and view all the answers

    What is the consequence of a positive transpulmonary pressure (TPP)?

    <p>It maintains airway patency.</p> Signup and view all the answers

    Which muscles are primarily involved in the inspiration process?

    <p>Diaphragm and external intercostals.</p> Signup and view all the answers

    What physiological condition can lead to a decrease in the inward recoil of lung tissue?

    <p>Emphysema.</p> Signup and view all the answers

    What does LaPlace's Law state about the relationship between pressure and alveolus size?

    <p>Pressure required decreases with a decrease in radius.</p> Signup and view all the answers

    How does surfactant affect the surface tension in alveoli?

    <p>Surfactant lowers surface tension, counteracting increased radius effects.</p> Signup and view all the answers

    What is the primary function of pulmonary surfactant produced by Type II alveolar cells?

    <p>To reduce surface tension, preventing alveoli collapse.</p> Signup and view all the answers

    What condition can arise from a lack of surfactant in premature infants?

    <p>Respiratory Distress Syndrome.</p> Signup and view all the answers

    How can the maturation of surfactant-producing cells be stimulated?

    <p>By administering cortisol to the mother.</p> Signup and view all the answers

    In the context of ventilation, what does 'bulk flow of air' refer to?

    <p>The movement of air from high pressure to low pressure.</p> Signup and view all the answers

    What role does the Poiseuille equation play in the respiratory mechanics?

    <p>It helps in calculating airway resistance and air flow.</p> Signup and view all the answers

    What component primarily makes up pulmonary surfactant?

    <p>Dipalmitoyl phosphatidylcholine (DPPC).</p> Signup and view all the answers

    Study Notes

    Lung Expansion and Pressure Changes

    • Transpulmonary pressure (TPP) increases during lung expansion.
    • TPP is the difference between alveolar pressure (PALV) and intrapleural pressure (PIP), (TPP = PALV - PIP).
    • During inspiration, the diaphragm and external intercostal muscles contract, increasing chest volume and pulling open the lungs.
    • Intrapleural pressure decreases, and alveolar pressure also drops during chest expansion, creating a pressure gradient that promotes air flow into the lungs.

    Expiration

    • Expiration is a passive process during normal quiet breathing.
    • At the end of inspiration, the diaphragm and inspiratory muscles relax.
    • The lungs, expanded beyond functional residual capacity (FRC), recoil towards their resting position.
    • This decreases thoracic volume, compressing air in the alveoli, causing it to exceed atmospheric pressure, and air flows out.
    • During exercise or forced expiration, the internal intercostals and abdominal muscles contract.
    • Contraction of these muscles actively decrease chest volume.

    Lung Compliance

    • Lung compliance (C) is the change in lung volume (ΔV) per unit change in transpulmonary pressure (ΔP).
    • It describes how much effort is required to inflate the lungs.
    • Compliance is inversely proportional to the recoil forces of the lung tissue.
    • Higher compliance means less effort is needed to expand the lungs, while lower compliance requires more negative intrapleural pressure.
    • During inspiration, negative intrapleural pressure must be increased to expand the lungs with reduced compliance.

    Surfactant and Its Role

    • Surfactant is a substance produced by type II alveolar cells.
    • It lowers surface tension within the alveoli.
    • The effect of surfactant is inversely proportional to surface area, preventing smaller alveoli from collapsing into larger ones.
    • It helps maintain alveolar stability and reduces the effort required for breathing.

    Airway Resistance and Airflow

    • Airway resistance is the resistance to airflow within the airways.
    • It's determined by airway diameter and other factors.
    • Dynamic compression of the airways is a phenomenon where airways narrow during expiration, increasing airway resistance.
    • According to Poiseuille's Law, airway resistance is inversely proportional to the fourth power of the radius, meaning even small changes in radius can significantly impact resistance.

    Functional Residual Capacity (FRC)

    • FRC is the volume of air remaining in the lungs at the end of normal expiration.
    • It is influenced by factors such as lung compliance, chest wall compliance, and airway resistance.

    Dead Space

    • Anatomic dead space refers to the volume of air within the conducting airways that does not participate in gas exchange.
    • Physiologic dead space includes the volume of air in the alveoli that are poorly ventilated or not perfused.

    Ventilation Volumes and Capacities

    • Tidal Volume (TV): The amount of air moved in and out of the lungs during a normal breath.
    • Inspiratory Reserve Volume (IRV): The extra amount of air that can be inhaled after normal inspiration.
    • Expiratory Reserve Volume (ERV): The extra amount of air that can be exhaled after normal expiration.
    • Residual Volume (RV): The amount of air remaining in the lungs after a maximal exhalation.
    • Inspiratory Capacity (IC): The maximum amount of air that can be inhaled after a normal expiration (TV + IRV).
    • Vital Capacity (VC): The maximum amount of air that can be exhaled after a maximal inhalation (TV + IRV + ERV).
    • Total Lung Capacity (TLC): The total amount of air the lungs can hold (VC + RV).
    • Functional Residual Capacity (FRC): The volume of air remaining in the lungs at the end of a normal expiration (ERV + RV).

    Gas Laws and Respiration

    • Dalton's Law: The total pressure of a mixture of gases is equal to the sum of the partial pressures of the individual gases.
    • Henry's Law: The amount of a gas dissolved in a liquid is directly proportional to the partial pressure of that gas above the liquid.

    Anatomy of the Respiratory System

    • Lungs: Paired organs, right and left, covered by the visceral pleura.
    • Chest Wall: Includes the rib cage, respiratory muscles (external and internal intercostals), and the diaphragm.
    • Parietal Pleura: Lines the chest wall.
    • Intrapleural Space: The space between the visceral and parietal pleura, contains a small volume of intrapleural fluid.
    • Pneumothorax: A collapsed lung caused by air entering the intrapleural space.

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    Related Documents

    Mechanics of Respiration I & II - 2023 - Syllabus.pdf

    Description

    Explore the mechanisms of lung expansion and expiration in this quiz. Learn about transpulmonary pressure, the roles of the diaphragm and intercostal muscles, and the differences between normal and forced expiration. Test your understanding of these critical respiratory processes.

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