Biology Chapter on Respiratory System Functions
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Questions and Answers

Which step in external respiration involves the movement of gases between the alveoli and blood?

  • Internal respiration
  • Ventilation
  • Gas exchange (correct)
  • Transport of gases

    • What role does the autonomic nervous system play in respiration?

  • Regulates blood pressure during respiration
  • Facilitates vocalization
  • Controls airway resistance (correct)
  • Carries oxygen to tissues

    • What is the primary factor influencing the diffusion of gases in the lungs?

  • Pressure of the surrounding environment
  • Concentration gradient (correct)
  • Humidity level
  • Temperature of the air

    • Which of the following accurately defines minute ventilation?

    <p>Total volume of air breathed in one minute</p> Signup and view all the answers

    What is the purpose of the respiratory system in regulating pH?

    <p>To maintain acid-base balance through CO2 removal</p> Signup and view all the answers

    Which of the following actions are vital in the process of ventilation?

    <p>Inhalation and exhalation cycles</p> Signup and view all the answers

    Which component is NOT part of the steps of external respiration?

    <p>Internal respiration</p> Signup and view all the answers

    What constitutes dead space in the respiratory system?

    <p>A volume of air that does not participate in gas exchange</p> Signup and view all the answers

    How is oxygen primarily transported in the body?

    <p>Bound to hemoglobin</p> Signup and view all the answers

    What is the primary method of carbon dioxide transport in the bloodstream?

    <p>As bicarbonate</p> Signup and view all the answers

    Where does internal respiration primarily occur?

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

    Which structure is not part of the upper airways?

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

    What is the primary role of the conducting zone in the respiratory system?

    <p>Air humidification and warming</p> Signup and view all the answers

    How does the sympathetic nervous system affect airway resistance?

    <p>Decreases resistance via bronchodilation</p> Signup and view all the answers

    What happens to airway resistance when the parasympathetic nervous system is activated?

    <p>Airway resistance increases</p> Signup and view all the answers

    Which part of the respiratory system is involved in the exchange of gases?

    <p>Respiratory zone</p> Signup and view all the answers

    What is the primary cause of asthma attacks?

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

    What is the role of cilia and mucus-secreting cells in the conducting zone?

    <p>Removing airborne particles</p> Signup and view all the answers

    What does anatomical dead space refer to?

    <p>The volume of air in the conducting zone</p> Signup and view all the answers

    What is the function of Type II alveolar cells?

    <p>Synthesize pulmonary surfactant</p> Signup and view all the answers

    What characterizes the pulmonary blood pressure?

    <p>Approximately 15 mmHg</p> Signup and view all the answers

    How does the distribution of pulmonary blood flow change when standing?

    <p>Lowest at the top of the lung</p> Signup and view all the answers

    What is the main mechanism of gas movement in the respiratory zone?

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

    What is the role of alveolar macrophages?

    <p>Remove pathogens from the alveoli</p> Signup and view all the answers

    What feature of the pulmonary vasculature allows for low resistance and high output?

    <p>Large surface area</p> Signup and view all the answers

    What type of receptors does albuterol activate to manage asthma symptoms?

    <p>Beta-2 adrenergic receptors</p> Signup and view all the answers

    What is the approximate number of alveoli in a lung?

    <p>300 million</p> Signup and view all the answers

    What does the respiratory zone include?

    <p>Respiratory bronchioles and alveoli</p> Signup and view all the answers

    What does dead space volume (VD) represent in the context of tidal volume (VT)?

    <p>Volume of air not available for gas exchange</p> Signup and view all the answers

    Which equation correctly calculates the alveolar ventilation volume (VA)?

    <p>VA = VT - VD</p> Signup and view all the answers

    If a person's tidal volume (VT) is 500 ml and their dead space volume (VD) is 150 ml, what is their alveolar ventilation volume (VA)?

    <p>350 ml</p> Signup and view all the answers

    What is the main limitation of minute ventilation (V) as an estimate for gas exchange?

    <p>It does not consider the volume of dead space</p> Signup and view all the answers

    What would be the alveolar minute ventilation (VA) for a person with a respiratory rate of 12 breaths/min, tidal volume (VT) of 500 ml, and dead space volume (VD) of 150 ml?

    <p>4200 ml/min</p> Signup and view all the answers

    What is the primary reason gas diffusion is slower in the presence of increased fibrotic tissue?

    <p>Increased diffusion distance</p> Signup and view all the answers

    Which of the following factors is inversely proportional to the rate of gas diffusion according to Fick's Law?

    <p>Membrane thickness</p> Signup and view all the answers

    What is the consequence of a lung resection in terms of gas diffusion?

    <p>Decreased surface area</p> Signup and view all the answers

    If a person's tidal volume increases during exercise, what effect does this have on gas diffusion?

    <p>Increased pressure gradient</p> Signup and view all the answers

    What can be inferred about the diffusion of gases when a person travels to high altitudes, like Cuzco, Peru?

    <p>Decreased pressure gradient</p> Signup and view all the answers

    What is the thickness of the membrane for gas diffusion across the alveolar-capillary barrier?

    <p>0.5 μm</p> Signup and view all the answers

    What happens to the diffusion rate when a person engages in physical exercise?

    <p>Increases due to increased surface area</p> Signup and view all the answers

    In the context of gas diffusion, what does Fick's Law indicate about gases under normal conditions?

    <p>Diffusion occurs through three layers</p> Signup and view all the answers

    How long do red blood cells typically spend in the capillaries while traversing the alveoli?

    <p>0.75 seconds</p> Signup and view all the answers

    Which of the following conditions would likely NOT result in decreased gas diffusion?

    <p>Increased pressure gradient</p> Signup and view all the answers

    Study Notes

    Why we need a respiratory system

    • O2 is essential for the production of ATP via glucose metabolism.
    • The respiratory system delivers O2 from the air to the tissues and removes CO2 from tissues to the air.

    Additional Functions of the Respiratory System

    • Regulates blood pH.
    • Enables vocalization.
    • Defends against airborne pathogens by removing inhaled particles.
    • Lungs process certain blood-borne substances:
      • Angiotensin-converting enzyme converts angiotensin I to angiotensin II.
      • Enzymes inactivate bradykinin and some prostaglandins.
      • Certain immunoglobulins (IgA) are released.

    Steps of External Respiration

    • Ventilation: Movement of air between the atmosphere and alveoli. Ventilation rate adjusts to meet the body's need for O2 uptake and CO2 removal.
    • Gas Exchange: Exchange of O2 and CO2 between air in the alveoli and blood by diffusion.
    • Transport of O2 and CO2:
      • O2 is primarily transported bound to hemoglobin.
      • CO2 is primarily transported as bicarbonate.
    • Gas Exchange: Exchange of O2 and CO2 between blood and tissues. This occurs in the mitochondria.

    Organization of the Respiratory System

    • Upper Airways:
      • Includes nasal and oral cavities, pharynx, and larynx (vocal cords).
    • Trachea: Connects the upper airways to the lungs.
    • Lungs:
      • Contain bronchi, bronchioles, and alveoli.
      • Have smooth muscle and connective tissue.
      • Contain the pulmonary circulation.
    • Muscles of Respiration: Muscles that facilitate breathing.
    • Rib Cage and Pleura: Structures that protect the lungs and facilitate breathing.
    • Parts of the CNS that regulate respiration: Structures in the central nervous system responsible for controlling breathing.

    Functional Anatomy

    • Conducting Zone:
      • Also called the anatomical dead space.
      • Includes the nasal cavity, trachea, bronchi, and bronchioles down to the terminal bronchioles.
      • Approximately 150 ml in volume.
    • Respiratory Zone:
      • Also called the exchange zone.
      • Includes the respiratory bronchioles, alveolar ducts, and alveoli.
      • Alveolar ventilation volume is the volume of air that reaches the alveoli.

    Conducting Zone Functions

    • Moves air into and out of the respiratory zone for gas exchange.
    • Humidifies and warms the air stream.
    • Removes dust through cilia and mucous-secreting cells.
    • Decreases the velocity of airflow.

    Autonomic Nervous System Control of Airway Tone

    • The autonomic nervous system (ANS) regulates the tone of the smooth muscle in the bronchi and bronchioles:
      • Sympathetic Nervous System (SNS):
        • Activates β2 adrenergic receptors on bronchial smooth muscle.
        • Causes airway dilation.
        • Decreases airway resistance.
      • Parasympathetic Nervous System (PNS):
        • Activates cholinergic M3 receptors on bronchial smooth muscle.
        • Causes airway constriction.
        • Increases airway resistance.

    Asthma

    • Asthma: A disease caused by inappropriate airway muscle tone.
    • Caused by: Broncoconstriction associated with chronic inflammatory conditions.
    • Treatment: Often treated with albuterol (β2 adrenergic receptor agonist) which relaxes the airway muscles.

    Pulmonary Vasculature

    • Pulmonary Artery: Receives all of the right heart output.
    • Low Pulmonary Blood Pressure: Arterial pressure is approximately 15 mmHg.
    • Large Surface Area: Even though the blood pressure is low, the cardiac output is 5-6 L/min, which means the pulmonary circulation has a large surface area and low resistance.
    • Uneven Blood Flow: When standing, pulmonary blood flow is not distributed evenly due to gravity.
      • Lowest at the top of the lung.
      • Highest at the bottom of the lung.

    Respiratory Zone

    • Respiratory Zone: Includes the respiratory bronchioles, alveolar ducts, and alveoli.
    • Gas Movement: Gas movement primarily occurs via diffusion, from high pressure to low pressure.
      • CO2 diffuses into the alveoli.
      • O2 diffuses out of the alveoli.
    • Design Feature: The respiratory zone has a large surface area for diffusion.

    Alveoli

    • Alveoli: Small air sacs in the lungs where gas exchange occurs.
    • Alveolar Cells:
      • Type I: Alveolar epithelium.
      • Type II: Synthesize pulmonary surfactant.
      • Alveolar macrophages: Immune cells that engulf foreign particles.
    • Surface Area: There are approximately 300 million alveoli per lung.
      • Alveolar diameter is approximately 200 μm.
      • Total alveolar surface area is 50-100 m2 (equivalent to a tennis court!).

    Blood Gas Diffusion Across the Alveolar-Capillary Interface

    • Red Blood Cells: Spend approximately 0.75 seconds in a capillary, traversing 2-3 alveoli.
    • Small Diffusion Distance: The distance between the alveoli and the capillaries is small (0.5 μm).
      • Three layers: alveolar epithelium, interstitial fluid, and capillary endothelium.

    Diffusion of Gases: Fick's Law

    • Fick's Law: Describes the factors that influence the rate of diffusion.
    • Factors Influencing Diffusion Rate:
      • Diffusion Coefficient: The ability of a gas to diffuse through a membrane.
      • Surface Area: The area available for diffusion.
      • Pressure Gradient: The difference in partial pressure of the gas across the membrane.
      • Membrane Thickness: The thickness of the membrane through which the gas must diffuse (diffusion distance).
      • Diffusion is directly proportional to: Diffusion coefficient, surface area, and pressure gradient.
      • Diffusion is inversely proportional to: Membrane thickness (diffusion distance).

    Clinical Connection: Factors that Affect Gas Diffusion Rate

    • Conditions that decrease diffusion rate:
      • Restrictive lung disease: Increased fibrotic tissue in the lungs increases diffusion distance.
      • Lung resection: Decreases surface area for diffusion.
      • High altitude: Decreases pressure gradient.
    • Condition that increases diffusion rate: Exercise due to increased surface area.

    Tidal Volume and Alveolar Ventilation Volume

    • Tidal Volume (VT): The volume of air moved into and out of the lungs during a normal breath. This volume changes to meet metabolic needs.
    • Dead Space Volume (VD): The volume of each breath that does not participate in gas exchange (usually about 150 ml).
    • Alveolar Ventilation Volume (VA): The volume of each breath that actually participates in gas exchange.
      • VA = VT - VD

    Ventilation Rates

    • Minute Ventilation (V): The total volume of air moved into and out of the lungs per minute.
      • V = VT x (breaths/min)
    • Alveolar (Functional) Minute Ventilation (VA): A better estimate of gas exchange that corrects for physiological dead space.
      • VA = VA x (breaths/min)

    Example Ventilation Calculations

    • Example:
      • Respiratory rate: 12 breaths/min
      • Tidal volume (VT): 500 ml
      • Dead space volume (VD): 150 ml
    • Minute Ventilation: V = 500 ml x 12 breaths/min= 6000 ml/min.
    • Alveolar Minute Ventilation:
      • VA = 500 ml - 150 ml = 350 ml.
      • VA = 350 ml x 12 breaths/min = 4200 ml/min.

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    Description

    Explore the crucial roles of the respiratory system in delivering oxygen and removing carbon dioxide. This quiz covers its functions, the steps of external respiration, and how it regulates blood pH and supports vocalization. Test your understanding of these vital processes and the biological significance behind them.

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