23.5 Pulmonary Ventilation
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Questions and Answers

Which muscles are involved in quiet breathing?

  • Sternocleidomastoid and scalene muscles
  • Diaphragm and external intercostals (correct)
  • Pectoralis major and latissimus dorsi
  • Internal intercostals and abdominal muscles

    • How does the diaphragm move during contraction?

  • It does not move during contraction
  • Its central portion flattens and moves superiorly
  • Its central portion flattens and moves inferiorly (correct)
  • It becomes more dome-shaped

    • What is the function of the external intercostal muscles during contraction?

  • They elevate the ribs (correct)
  • They depress the ribs
  • They have no effect on the ribs
  • They rotate the ribs

    • Which of the following are muscles of forced inspiration?

    <p>Sternocleidomastoid and scalene muscles</p> Signup and view all the answers

    What happens when the muscles of quiet breathing relax?

    <p>Air is expelled from the lungs</p> Signup and view all the answers

    Which muscles are involved in forced expiration?

    <p>Internal intercostals and abdominal muscles</p> Signup and view all the answers

    What is the primary stimulus for breathing in certain respiratory disorders like emphysema?

    <p>Decreased blood Po2 levels</p> Signup and view all the answers

    What happens when oxygen is administered to a person experiencing the hypoxic drive?

    <p>It interferes with their ability to breathe on their own</p> Signup and view all the answers

    What happens to the chemoreceptors' sensitivity to Pco2 in the hypoxic drive?

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

    Which receptors, when stimulated by body movement, increase the depth of breathing?

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

    What is the function of the Hering-Breuer reflex?

    <p>To prevent overinflation of the lungs</p> Signup and view all the answers

    Which receptors are stimulated by stretch within the lungs and bronchioles?

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

    What are the muscles responsible for forced inspiration and expiration collectively referred to as?

    <p>Accessory muscles of breathing</p> Signup and view all the answers

    In which dimensions does the thoracic cavity change volume during breathing?

    <p>Vertical, lateral, and anterior-posterior</p> Signup and view all the answers

    Which movement causes an increase in the vertical dimension of the thoracic cavity during inspiration?

    <p>Contraction of the diaphragm</p> Signup and view all the answers

    What causes the vertical dimensions of the thoracic cavity to decrease during expiration?

    <p>Relaxation of the diaphragm</p> Signup and view all the answers

    During quiet breathing, how much do the vertical dimensions of the thoracic cavity typically change?

    <p>A few millimeters</p> Signup and view all the answers

    What causes greater changes in the superior movement of the diaphragm during forced expiration?

    <p>Contraction of the abdominal muscles</p> Signup and view all the answers

    Why are some balloons easier to inflate compared to others?

    <p>They have more compliance due to stretchable walls.</p> Signup and view all the answers

    What primarily influences the amount of surface tension in the alveoli?

    <p>The production of pulmonary surfactant.</p> Signup and view all the answers

    In which condition do premature infants face collapsing alveoli with each expiration?

    <p>Respiratory distress syndrome (RDS).</p> Signup and view all the answers

    What happens to resistance in the airways if compliance decreases?

    <p>Resistance increases.</p> Signup and view all the answers

    Which factor causes high surface tension within the alveoli?

    <p>Insufficient production of pulmonary surfactant.</p> Signup and view all the answers

    How does resistance to airflow change with bronchiole constriction?

    <p>Resistance increases.</p> Signup and view all the answers

    What is the primary function of the baroreceptors when they are overstretched?

    <p>They send nerve signals through the vagus nerves to the respiratory center to shut off inspiration activity, resulting in expiration</p> Signup and view all the answers

    What is the role of the medulla oblongata in the sneezing and coughing reflexes?

    <p>The medulla oblongata contains the sneezing and coughing nuclei, which initiate nerve signals along motor neurons to cause the vocal cords to close and the abdominal muscles to contract forcefully</p> Signup and view all the answers

    How do higher brain centers, such as the hypothalamus, limbic system, and cerebral cortex, influence breathing rate?

    <p>The hypothalamus increases the breathing rate if the body is warm and decreases it if the body is cold, while the limbic system alters the breathing rate in response to emotions and emotional memories</p> Signup and view all the answers

    What is the purpose of the explosive blast of exhaled air generated by the sneezing and coughing reflexes?

    <p>To potentially remove the irritant that triggered the sneezing or coughing reflex</p> Signup and view all the answers

    What is the primary role of the baroreceptors in infants?

    <p>To serve as a protective reflex to control respiration in infants</p> Signup and view all the answers

    What factor influences airflow by establishing air pressure gradients in the respiratory system?

    <p>Skeletal muscles of breathing</p> Signup and view all the answers

    Which factor directly affects the resistance to airflow in the respiratory system?

    <p>Bronchiole diameter</p> Signup and view all the answers

    In the cardiovascular system, what is responsible for driving blood through the blood vessels?

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

    What opposes the airflow in the respiratory system due to factors like compliance and surface tension?

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

    Which system experiences resistance within blood vessels similar to how air experiences resistance in the respiratory tract?

    <p>Cardiovascular system</p> Signup and view all the answers

    What causes an increase in airflow in the respiratory system?

    <p>Weaker muscular force exerted</p> Signup and view all the answers

    According to the passage, which of the following is the best analogy for the relationship between the medullary respiratory center and the pontine respiratory center?

    <p>The medullary respiratory center is the boss, and the pontine respiratory center is an external regulatory group.</p> Signup and view all the answers

    If a spinal cord injury occurs at C2 or above, what would be the predicted consequence to breathing?

    <p>The phrenic nerves would be affected, leading to paralysis of the diaphragm and inability to breathe.</p> Signup and view all the answers

    If a spinal cord injury occurs between C6 and T11, what would be the predicted consequence to breathing?

    <p>The intercostal nerves would be affected, leading to paralysis of the intercostal muscles and difficulty with expiration.</p> Signup and view all the answers

    Which of the following receptors is NOT mentioned in the passage as being able to alter breathing rate and depth through reflexes?

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

    According to the passage, what is the primary function of the Hering-Breuer reflex?

    <p>To prevent over-inflation of the lungs during inspiration.</p> Signup and view all the answers

    What is the primary stimulus for breathing in certain respiratory disorders like emphysema?

    <p>Decreased $ ext{O}_{2}$ levels</p> Signup and view all the answers

    What is the main difference between minute ventilation and alveolar ventilation?

    <p>Minute ventilation measures the total air inhaled and exhaled, while alveolar ventilation measures only the air reaching the alveoli.</p> Signup and view all the answers

    What is the relationship between anatomic dead space and physiologic dead space?

    <p>Anatomic dead space is the volume of air in the conducting zone, while physiologic dead space is the volume of air that does not participate in gas exchange.</p> Signup and view all the answers

    If the resistance to airflow increases, what change in breathing must occur to maintain adequate alveolar ventilation?

    <p>Increase in both respiratory rate and tidal volume.</p> Signup and view all the answers

    What is the approximate volume of anatomic dead space in a person weighing 150 pounds?

    <p>150 mL</p> Signup and view all the answers

    If a person's minute ventilation is 6000 mL and their anatomic dead space is 150 mL, what is their alveolar ventilation?

    <p>5850 mL</p> Signup and view all the answers

    What is the normal tidal volume and respiratory rate for an adult, according to the text?

    <p>500 mL, 12 breaths/min</p> Signup and view all the answers

    What is the primary function of the forced expiratory volume in 1 second (FEV1) test?

    <p>To distinguish between chronic obstructive and restrictive pulmonary diseases</p> Signup and view all the answers

    What is the typical range for the forced expiratory volume in 1 second (FEV1) in a healthy individual?

    <p>75% to 85% of vital capacity</p> Signup and view all the answers

    What is the maximum voluntary ventilation (MVV) test used to measure?

    <p>The greatest amount of air that can be both inspired and expired in one minute</p> Signup and view all the answers

    What is a typical value for maximum voluntary ventilation (MVV) in healthy individuals?

    <p>30 L/min</p> Signup and view all the answers

    Which statement about individuals with respiratory disorders is true, according to the text?

    <p>They have impaired ability to inspire, expire, or both</p> Signup and view all the answers

    What is the primary purpose of pulmonary function tests like FEV1 and MVV?

    <p>To distinguish between different types of respiratory disorders</p> Signup and view all the answers

    What is the inspiratory capacity (IC) composed of?

    <p>Tidal volume and inspiratory reserve volume</p> Signup and view all the answers

    Which respiratory capacity includes the residual volume?

    <p>Total lung capacity (TLC)</p> Signup and view all the answers

    What does forced expiratory volume (FEV) measure?

    <p>Percentage of the vital capacity forcefully expelled</p> Signup and view all the answers

    Which of the following is true about functional residual capacity (FRC)?

    <p>It is the sum of inspiratory reserve volume and residual volume</p> Signup and view all the answers

    What is the primary significance of vital capacity (VC)?

    <p>Maximum amount of air lungs can forcefully expire</p> Signup and view all the answers

    What does total lung capacity (TLC) represent?

    <p>Maximum amount of air lungs can hold including residual volume</p> Signup and view all the answers

    Study Notes

    Respiratory System

    • Hypoxic Drive: In certain respiratory disorders, such as emphysema, the decreased ability to expire carbon dioxide leads to decreased blood Po2 levels, which becomes the stimulus for breathing.
    • Chemoreceptors: Decreased Po2 levels stimulate chemoreceptors, which are less sensitive to Pco2 levels. Administering oxygen would elevate Po2 levels and interfere with a person's ability to breathe on their own.

    Altering Breathing Patterns

    • Proprioceptors: Stimulated by body movement, proprioceptors increase nerve signals to the respiratory center, leading to an increase in breathing depth.
    • Baroreceptors: Stimulated by stretch, baroreceptors initiate a reflex to prevent overstretching of the lungs by inhibiting inspiration activities, known as the Hering-Breuer reflex.
    • Irritant Receptors: Stimulated by irritants, irritant receptors initiate a sneezing or coughing reflex to remove the irritant.

    Mechanics of Breathing

    • Skeletal Muscles of Breathing: The diaphragm and external intercostals are involved in quiet breathing, while the muscles of forced inspiration and forced expiration are classified as accessory muscles of breathing.
    • Volume Changes: Contraction of breathing muscles causes thoracic cavity volume changes in three dimensions: vertically, laterally, and in an anterior-posterior direction.
    • Pressure Changes: Pressure changes result from volume changes, based on Boyle's gas law.

    Minute Ventilation and Alveolar Ventilation

    • Minute Ventilation: The volume of air taken in during 1 minute, calculated by multiplying the tidal volume by the number of breaths per minute.
    • Alveolar Ventilation: The amount of air that reaches the alveoli and is available for gas exchange per minute.
    • Anatomic Dead Space: The collective space in the conducting zone where there is no exchange of respiratory gases, with an average volume of approximately 150 mL.

    Reflexes and Higher Brain Centers

    • Reflexes: Reflexes can alter breathing rate and depth, primarily initiated by chemoreceptors, but also by proprioceptors, baroreceptors, and irritant receptors.
    • Higher Brain Centers: The hypothalamus, limbic system, and cerebral cortex can influence breathing rate in response to various factors, such as temperature, emotions, and emotional memories.

    Airflow and Resistance

    • Airflow: Directly related to the pressure gradient and inversely related to resistance.
    • Pressure Gradient: Established by the skeletal muscles of breathing, with a steeper gradient resulting in greater airflow.
    • Resistance: Opposes airflow, influenced by bronchiole diameter, compliance, and surface tension within the alveoli.

    Pulmonary Function Tests

    • Forced Expiratory Volume (FEV): The percentage of the vital capacity that can be forcefully expelled in a specific period of time, such as FEV1, which is the vital capacity percentage that is expired in 1 second.
    • Maximum Voluntary Ventilation (MVV): The greatest amount of air that can be taken into and then expelled from the lungs in 1 minute.
    • Respiratory Capacities: Calculated from the summation of two or more respiratory volumes, including inspiratory capacity, functional residual capacity, vital capacity, and total lung capacity.

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    Respiration: Pulmonary Ventilation PDF

    Description

    Explore the various components involved in breathing mechanics including skeletal muscles, thoracic cavity volume changes, pressure gradients, and associated volumes and pressures. Learn how these factors work together to facilitate the process of breathing.

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