BMED13-125: Normal Lung Function Review
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Questions and Answers

What primarily determines the direction of airflow in the lungs?

  • Transpulmonary pressure
  • Intrapleural pressure
  • Atmospheric pressure
  • Intrapulmonary pressure (correct)

    • Which factor is NOT listed as affecting pulmonary ventilation?

  • Oxygen concentration (correct)
  • Airway resistance
  • Alveolar surface tension
  • Lung compliance

    • How does bronchoconstriction affect airway resistance?

  • It has no effect on airway resistance.
  • It decreases airway resistance.
  • It increases airway resistance. (correct)
  • It stabilizes airway resistance.

    • What is the relationship between airway diameter and airway resistance?

    <p>Inversely proportional</p> Signup and view all the answers

    What happens to the intrapleural pressure when the lungs are fully inflated?

    <p>It remains approximately 4 mmHg less than intrapulmonary pressure.</p> Signup and view all the answers

    Which pressure is defined as the difference between intrapulmonary pressure and intrapleural pressure?

    <p>Transpulmonary pressure</p> Signup and view all the answers

    What effect does mucus have on airway resistance during respiratory disorders?

    <p>It narrows airways, increasing resistance.</p> Signup and view all the answers

    Which of the following statements about transpulmonary pressure is correct?

    <p>It prevents the lungs from collapsing.</p> Signup and view all the answers

    What role do coarsely haired nostrils play in respiratory defence?

    <p>They filter large particles from inhaled air.</p> Signup and view all the answers

    How do the nasal conchae contribute to respiratory defence during exhalation?

    <p>They reclaim heat and moisture from the exhaled air.</p> Signup and view all the answers

    What is the primary function of alveolar macrophages in the lungs?

    <p>To engulf and digest trapped particles.</p> Signup and view all the answers

    Which component of the respiratory system continuously sweeps mucus towards the pharynx?

    <p>Ciliated epithelium</p> Signup and view all the answers

    What is the primary purpose of the goblet cells in the respiratory passageways?

    <p>To produce mucus for trapping particles.</p> Signup and view all the answers

    What effect does acetylcholine have on bronchial smooth muscle?

    <p>Bronchoconstriction via M3 muscarinic receptors</p> Signup and view all the answers

    Which nerve is primarily responsible for parasympathetic innervation of the airways?

    <p>Vagus nerve</p> Signup and view all the answers

    What is the primary role of circulating adrenaline in airway control?

    <p>Promoting bronchodilation by acting on β2-adrenoceptors</p> Signup and view all the answers

    Which of the following muscles does the sympathetic nervous system have significant control over in the airways?

    <p>None, sympathetic innervation is minimal</p> Signup and view all the answers

    How does parasympathetic innervation affect vascular smooth muscle in the airways?

    <p>It causes vasodilation via endothelium</p> Signup and view all the answers

    What type of receptors does adrenaline act upon in the airways?

    <p>β2-adrenoceptors</p> Signup and view all the answers

    Which physiological process is directly influenced by the vagus nerve in respiratory control?

    <p>Bronchial smooth muscle contraction</p> Signup and view all the answers

    What does the activation of M3 muscarinic receptors in the airway smooth muscle cause?

    <p>Bronchoconstriction</p> Signup and view all the answers

    Where is airflow resistance the greatest in the respiratory system?

    <p>In large bronchioles</p> Signup and view all the answers

    What effect does surfactant have on lung compliance?

    <p>Increases lung compliance</p> Signup and view all the answers

    Which condition would likely lead to decreased lung compliance?

    <p>Pulmonary fibrosis</p> Signup and view all the answers

    What is primarily responsible for the nervous control of bronchial smooth muscle?

    <p>Parasympathetic innervation</p> Signup and view all the answers

    What is the main function of surfactant in the alveoli?

    <p>Prevents alveolar collapse</p> Signup and view all the answers

    What role does alveolar surface tension play in lung function?

    <p>Contributes to lung collapse</p> Signup and view all the answers

    In which of the following conditions would lung compliance likely increase?

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

    What factors contribute to decreased lung compliance? (Select all that apply)

    <p>Thoracic mobility restrictions</p> Signup and view all the answers

    What is the primary effect of β2-adrenoceptors activated by circulating adrenaline?

    <p>Bronchodilation</p> Signup and view all the answers

    Which of the following neurotransmitters or modulators causes bronchodilation?

    <p>Nitric oxide</p> Signup and view all the answers

    What role do mast cells play in the response of bronchial smooth muscle?

    <p>They release histamine during allergic reactions.</p> Signup and view all the answers

    Which factor is categorized as an excitatory neurotransmitter that causes bronchoconstriction?

    <p>Neurokinin A</p> Signup and view all the answers

    What is the effect of irritants such as smoke and dust on bronchial smooth muscle?

    <p>They initiate local, non-nervous reactions causing constriction.</p> Signup and view all the answers

    Which of the following is NOT a local secretory factor that causes bronchoconstriction?

    <p>Adrenaline</p> Signup and view all the answers

    Which of the following correctly describes the role of vasoactive intestinal peptide (VIP) in bronchial smooth muscle control?

    <p>It acts as a co-transmitter with acetylcholine.</p> Signup and view all the answers

    Which mechanism primarily contributes to increased mucociliary clearance in the airways?

    <p>Stimulation of β2-adrenoceptors by adrenaline</p> Signup and view all the answers

    Study Notes

    BMED13-125: Exploring Human Disease - Review of Normal Lung Function & Airway Control

    • Learning Objectives:
      • Review previous knowledge of normal lung function
      • Explain the nervous & hormonal control of airways
      • Outline respiratory defence mechanisms
    • Useful Texts:
      • Marieb & Hoehn, 12th Ed., Chapter 22
      • Guyton & Hall, 14th Ed., Chapters 38-43

    Respiratory Pressures

    • Atmospheric pressure (Patm) is approximately 760 mmHg.
    • Negative pressure is less than 760 mmHg.
    • Positive pressure is greater than 760 mmHg.
    • Intrapulmonary pressure (Ppul) fluctuates with breathing. It eventually equals Patm. Ppul determines the direction of air flow.
    • Intrapleural pressure (Pip) is approximately 4 mmHg less than Ppul. This maintains a pull on the lungs.
    • Transpulmonary pressure (PTpul) is the difference between Ppul and Pip. This pressure prevents the lungs from collapsing.

    Pressure Changes During Inhalation and Exhalation

    • During inhalation:
      • Intrapulmonary pressure (Ppul) fluctuates with breathing, eventually equalizing to atmospheric pressure (Patm) at 760 mmHg, determining air flow direction. It is affected by negative pressure (less than 760 mmHg) and positive pressure (greater than 760 mmHg). Intrapleural pressure (Pip) is about 4 mmHg lower than Ppul.pressure decreases below atmospheric pressure.
      • Intrapleural pressure becomes more negative.
      • Tidal volume increases.
    • During exhalation:
      • Intrapulmonary pressure increases above atmospheric pressure.
      • Intrapleural pressure becomes less negative.
      • Tidal volume decreases.

    Mechanics & Pressure Changes During Inspiration

    • Sequence of events:
      1. Inspiratory muscles contract.
      2. Thoracic cavity volume increases.
      3. Lungs stretch; intrapulmonary volume increases.
      4. Intrapulmonary pressure drops to -1 mmHg.
      5. Air flows into lungs until intrapulmonary pressure equals atmospheric pressure.

    Mechanics & Pressure Changes During Expiration

    • Sequence of events:
      1. Inspiratory muscles relax.
      2. Thoracic cavity volume decreases.
      3. Elastic lungs recoil passively; intrapulmonary volume decreases.
      4. Intrapulmonary pressure rises to +1 mmHg
      5. Air flows out of lungs until intrapulmonary pressure equals atmospheric pressure.

    Airway Disorders

    • The respiratory tract includes bronchial, terminal bronchioles, respiratory bronchioles, and alveoli.
    • The diagram shows the bronchial tree, pulmonary arteries, veins, and capillary beds, as well as components such as elastic fibers, the pleura, and lymph vessels

    Factors Affecting Pulmonary Ventilation

    • Airway resistance:
      • Resistance to airflow is friction.
      • Inversely proportional to airway diameter.
      • Normally insignificant.
      • Disease increases resistance (mucus, inflammation, bronchoconstriction).
      • Bronchodilators decrease resistance and increase airflow.
    • Alveolar surface tension:
      • Caused by alveolar fluid.
      • Water molecules on the surface have a strong attractive force for each other attempting to contract alveoli, causing them to collapse.
      • Surfactant, secreted by type II alveolar cells, reduces surface tension and increases lung compliance.
    • Lung compliance:
      • Extent to which lung volume will expand for a given increase in transpulmonary pressure.
      • Depends on elasticity of lung tissue and alveolar surface tension.
      • Reduced compliance requires more force for breathing in and breathing out (e.g., fibrosis, reduced surfactant).

    Airway Control

    • Nervous control of bronchial smooth muscle:

      • Direct control of bronchioles by sympathetic nerves is minimal.
      • Parasympathetic innervation dominates.

    • Vagus nerve releases acetylcholine.

    • Acts on M3 muscarinic receptors, causing bronchoconstriction.

    • Neurohumoral control of bronchial smooth muscle:

      • Circulating adrenaline acts on β2-adrenoceptors, causing bronchodilation.

    • Local control of bronchial smooth muscle:

      • Local secretory factors (histamine, slow-reactive substance of anaphylaxis) can cause bronchoconstriction.
      • Irritants (smoke, dust) can initiate local, non-nervous reactions causing constriction.

    Respiratory Defence Mechanisms

    • The nose filters, heats, and moistens the air.
    • Airway defence:
      • Coarse hairs in the nose remove large particles.
      • Nasal passages warm and moisten incoming air.
      • Goblet cells and mucous glands secrete mucus to trap particles.
      • Ciliated epithelium (mucociliary escalator) sweeps mucus towards the pharynx.
    • Alveolar macrophages engulf trapped particles.

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    EHD Review of Resp Func & Airway Control 243 PDF

    Description

    This quiz covers the fundamentals of normal lung function and airway control. It focuses on the nervous and hormonal influences on airways and the body's respiratory defense mechanisms. Review the key concepts presented in Marieb & Hoehn and Guyton & Hall's textbooks for a comprehensive understanding.

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