Respiratory System Structure and Function
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Questions and Answers

What is the primary role of surfactant in maintaining alveolar stability?

  • It enhances the absorption of oxygen in the bloodstream.
  • It promotes contraction of lung muscles during exhalation.
  • It reduces surface tension in the alveoli, preventing collapse. (correct)
  • It increases intrapulmonary pressure during inhalation.

    • How does Boyle's Law relate to changes in lung volume and intrapulmonary pressure during inhalation?

  • A decrease in lung volume decreases the intrapulmonary pressure, allowing air to enter.
  • An increase in lung volume decreases the intrapulmonary pressure, allowing air to enter. (correct)
  • A decrease in lung volume increases the intrapulmonary pressure, restricting airflow.
  • An increase in lung volume increases the intrapulmonary pressure, forcing air out.

    • What happens to the alveolar pressure during quiet expiration?

  • Alveolar pressure decreases below atmospheric pressure.
  • Alveolar pressure remains constant regardless of lung volume.
  • Alveolar pressure increases above atmospheric pressure. (correct)
  • Alveolar pressure is equal to intrapleural pressure.

    • Which statement correctly describes the role of surfactant in alveolar expansion?

    <p>Surfactant ensures smaller alveoli do not collapse into larger ones.</p> Signup and view all the answers

    What triggers the passive process of quiet expiration?

    <p>Recoil of the lungs after being stretched.</p> Signup and view all the answers

    What is the main purpose of external respiration in the lungs?

    <p>To convert deoxygenated blood into oxygenated blood</p> Signup and view all the answers

    What causes surface tension in the alveoli?

    <p>The attraction between water molecules at the air-liquid interface</p> Signup and view all the answers

    How does surfactant affect alveolar stability?

    <p>It helps prevent alveoli from collapsing during exhalation</p> Signup and view all the answers

    What is internal respiration primarily responsible for?

    <p>The exchange of gases between systemic capillaries and tissue cells</p> Signup and view all the answers

    What is one result of increased surface tension in smaller alveoli?

    <p>Higher pressure leading to collapse</p> Signup and view all the answers

    Which of the following describes the effect of surfactant on lung compliance?

    <p>It improves lung compliance, making breathing easier</p> Signup and view all the answers

    What occurs if surface tension is not counteracted in the lungs?

    <p>Collapsing of smaller alveoli into larger ones</p> Signup and view all the answers

    Which type of cells secrete surfactant in the lungs?

    <p>Type II pneumocytes</p> Signup and view all the answers

    What would likely happen if the body had no surfactant?

    <p>There would be increasing chances of atelectasis</p> Signup and view all the answers

    What role does diffusion play in external respiration?

    <p>Enables gas exchange between alveolar air and blood</p> Signup and view all the answers

    What are the two main structural classifications of the respiratory system?

    <p>Upper and Lower respiratory systems</p> Signup and view all the answers

    Which of the following best describes the conducting zone of the respiratory system?

    <p>Includes the trachea and bronchi</p> Signup and view all the answers

    What occurs during the process of inspiration?

    <p>The external intercostal muscles contract</p> Signup and view all the answers

    How does expiration primarily occur?

    <p>Through the recoil of the lung tissue</p> Signup and view all the answers

    Which statement correctly describes internal respiration?

    <p>Gas exchange at the cellular level in tissues</p> Signup and view all the answers

    What role does the diaphragm play during inhalation?

    <p>It contracts and moves downward</p> Signup and view all the answers

    Which process is described as pulmonary ventilation?

    <p>Exchange of gases between the lungs and the atmosphere</p> Signup and view all the answers

    What is the primary function of the respiratory system?

    <p>To facilitate the exchange of oxygen and carbon dioxide</p> Signup and view all the answers

    What is the first step in the process of respiration?

    <p>External pulmonary ventilation</p> Signup and view all the answers

    During inhalation, what occurs to allow air to flow into the lungs?

    <p>The diaphragm contracts and moves downwards</p> Signup and view all the answers

    What triggers the process of exhalation?

    <p>The relaxation of inspiratory muscles</p> Signup and view all the answers

    What contributes to the passive nature of exhalation?

    <p>Elastic recoil of the chest wall and lungs</p> Signup and view all the answers

    How is the minute respiratory volume calculated?

    <p>Tidal volume multiplied by breath rate</p> Signup and view all the answers

    What is 'dead space air'?

    <p>Air that does not participate in gas exchange</p> Signup and view all the answers

    Which two forces contribute to the elastic recoil of the lungs?

    <p>Elastic fibers and surface tension from alveolar fluid</p> Signup and view all the answers

    What is the approximate normal value of minute respiratory volume in a healthy adult?

    <p>6 L/min</p> Signup and view all the answers

    Which gas does the blood gain during internal (pulmonary) ventilation?

    <p>Oxygen (O2)</p> Signup and view all the answers

    During internal (tissue) respiration, what does the blood lose?

    <p>Oxygen (O2)</p> Signup and view all the answers

    Study Notes

    Respiratory System Structure and Function

    • The respiratory system facilitates gas exchange, enabling cells to utilize oxygen and eliminate carbon dioxide. This system also regulates blood pH.
    • The respiratory system consists of two structural components:
      • Upper respiratory system: encompassing the nose, nasal cavity, pharynx, and associated structures.
      • Lower respiratory system: consisting of the larynx, trachea, bronchi, and lungs.
    • Functionally, the respiratory system consists of two zones:
      • Conducting zone: responsible for transporting air to the gas exchange areas. Includes the nose, nasal cavity, pharynx, larynx, trachea, bronchi, and bronchioles.
      • Respiratory zone: the site of gas exchange. Consists of respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.

    Breathing (Pulmonary Ventilation)

    • Breathing involves two cyclic phases:
      • Inhalation (inspiration): drawing air into the lungs.
      • Exhalation (expiration): expelling air from the lungs.
    • Inhalation is an active process needing energy input, with muscles contracting to increase lung volume.
    • Exhalation is usually a passive process, relying on the recoil of elastic tissues in the lungs and the thoracic cavity.

    Respiratory Events

    • Pulmonary ventilation: exchange of gases between the lungs and the atmosphere.
    • External respiration: exchange of gases between the alveoli and pulmonary capillaries.
    • Internal respiration: exchange of gases between systemic capillaries and tissue cells.

    Phases of Pulmonary Ventilation

    • Inhalation (inspiration):
      • Diaphragm contracts, moving downward and flattening.
      • Rib cage rises.
      • Lung volume increases.
      • Intrapulmonary pressure drops below atmospheric pressure.
      • Air flows into the lungs.
    • Exhalation (expiration):
      • Diaphragm relaxes, returning to its dome shape.
      • Rib cage lowers.
      • Lung volume decreases.
      • Intrapulmonary pressure rises above atmospheric pressure.
      • Air is forced out of the lungs.

    Physiology of Respiration

    • Respiration is a three-step process:
      • External pulmonary ventilation: exchange of air between the atmosphere and the alveoli in the lungs.
      • Internal (pulmonary) ventilation: exchange of gases between the alveoli and the blood in pulmonary capillaries across respiratory membrane. In this process, pulmonary capillary blood gains oxygen (O2) and loses carbon dioxide (CO2).
      • Internal (tissue) respiration: exchange of gases between blood in systemic capillaries and tissue cells. In this step the blood loses O2 and gains CO2.

    Composition of Air

    • Nitrogen: 78%
    • Oxygen: 20.9%
    • Other gases: 0.17%
    • Carbon dioxide: 0.03%

    Alveolar Ventilation

    • The alveoli are the primary site for gas exchange.
    • Dead space air is air that does not reach the alveoli and doesn't participate in gas exchange.
    • The normal amount of dead space air in a young adult male is roughly 150 ml.

    Pressure Changes During Breathing

    • Atmospheric pressure: about 760 mm Hg at sea level.
    • Alveolar pressure: pressure within the alveoli.
    • Intrapleural pressure: pressure within the pleural cavity.
    • Transpulmonary pressure: difference between alveolar and intrapleural pressure.

    Quiet Inspiration

    • An active process involving diaphragm and intercostal muscle contraction.
    • Increases thoracic cavity volume, leading to a lower alveolar pressure than atmospheric pressure.
    • Air moves into the lungs.

    Quiet Expiration

    • A passive process.
    • Lungs recoil after stretching, decreasing lung volume and increasing alveolar pressure above atmospheric pressure.
    • Air moves out of the lungs.

    Surface Tension

    • Surface tension is caused by the attraction between water molecules at the air-liquid interface in the alveoli.
    • Without surfactant, alveoli collapse easily because water molecules cling together causing the pressure in the alveoli to increase thereby impacting gas exchange efficiency
    • Pulmonary surfactant reduces surface tension, preventing alveolar collapse.

    Surfactant

    • A lipoprotein substance produced by type II alveolar cells.
    • Reduces surface tension within alveoli, improving lung compliance and preventing alveolar collapse.
    • Important factor for uniform alveolar expansion.
    • Plays a role in host defense by facilitating the clearance of pathogens and debris.

    Boyle's Law

    • Pressure and volume of gases are inversely proportional.
    • Increasing lung volume decreases intrapulmonary pressure, allowing air to flow into the lungs.
    • Decreasing lung volume increases intrapulmonary pressure, forcing air out of the lungs.

    External Respiration (Pulmonary Gas Exchange)

    • Oxygen (O2) and carbon dioxide (CO2) exchange between air in alveoli and blood in pulmonary capillaries.
    • Driven by pressure differences between gases in alveoli and blood.

    Internal Respiration (Systemic Gas Exchange)

    • O2 and CO2 exchange between systemic capillaries and tissue cells.
    • O2 diffuses from blood into tissue cells, and CO2 from tissue cells into blood.

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    Structure and Functions of the Respiratory System PDF

    Description

    Explore the intricate design and function of the respiratory system. This quiz covers aspects such as the upper and lower respiratory systems, along with the processes of breathing and gas exchange. Test your knowledge of how the body regulates oxygen and carbon dioxide levels.

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