Respiratory System - Lung Physiology
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Questions and Answers

What effect does maximum inspiration have on the anteroposterior thickness of the chest?

  • It increases by 20 percent. (correct)
  • It decreases by 20 percent.
  • It increases by 50 percent.
  • It remains the same.

    • Which muscles are primarily responsible for elevating the rib cage during inspiration?

  • Internal intercostals
  • External intercostals (correct)
  • Pectoral muscles
  • Abdominal recti

    • What role do the abdominal recti play during expiration?

  • They compress the abdominal contents upward against the diaphragm. (correct)
  • They lift the rib cage upward.
  • They pull the rib cage downward. (correct)
  • They do not contribute significantly.

    • What maintains the slight negative pressure in the pleural space during respiration?

    <p>Continuous suction of excess fluid into lymphatic channels.</p> Signup and view all the answers

    What is the normal pleural pressure at the beginning of inspiration?

    <p>–5 centimeters of water</p> Signup and view all the answers

    Which muscles assist in the elevation of the sternum during inspiration?

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

    Which type of pressure is present in the thin space between the lung pleura and the chest wall pleura?

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

    What happens to the lungs when there is no force to keep them inflated?

    <p>They collapse like a balloon.</p> Signup and view all the answers

    What is the primary function of pulmonary ventilation?

    <p>To facilitate the inflow and outflow of air between the atmosphere and the lung alveoli</p> Signup and view all the answers

    Which muscles primarily accomplish normal quiet breathing?

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

    What happens to the diaphragm during expiration?

    <p>It relaxes</p> Signup and view all the answers

    What additional force assists with rapid expiration during heavy breathing?

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

    Which method contributes to lung expansion by changing the chest cavity's shape?

    <p>Elevating and depressing the ribs</p> Signup and view all the answers

    What term defines the ability of the lungs to expand and contract efficiently?

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

    During normal inspiration, which muscle primarily contributes to expanding the thoracic cavity?

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

    What occurs to the rib cage during inhalation?

    <p>It elevates and expands</p> Signup and view all the answers

    What primarily determines the elastic forces of the lung tissue?

    <p>Elastin and collagen fibers interwoven among lung parenchyma</p> Signup and view all the answers

    Which of the following best explains the role of surfactant in the lungs?

    <p>Surfactant reduces surface tension within the alveoli</p> Signup and view all the answers

    What is the effect of surfactant on the surface tension of water in the alveoli?

    <p>Normal alveolar fluids without surfactant have lower surface tension than pure water</p> Signup and view all the answers

    Which statement accurately describes the difference between air-filled lungs and saline solution-filled lungs?

    <p>Transpleural pressures required for air-filled lungs are significantly higher</p> Signup and view all the answers

    What percentage of the surface area of alveoli is comprised of type II alveolar epithelial cells?

    <p>10 percent</p> Signup and view all the answers

    Which of the following accurately reflects the contribution of tissue elastic forces to total lung elasticity?

    <p>They represent one-third of the total lung elasticity</p> Signup and view all the answers

    In terms of surface tension, what is the range for normal fluids in the alveoli with surfactant?

    <p>5 to 30 dynes/cm</p> Signup and view all the answers

    What isolating condition occurs in saline solution-filled lungs compared to air-filled lungs?

    <p>Absence of surface tension effects due to lack of air</p> Signup and view all the answers

    What is the average alveolar pressure during normal inspiration?

    <p>-7.5 centimeters of water</p> Signup and view all the answers

    What must occur for air to flow into the alveoli during inspiration?

    <p>Alveolar pressure must fall slightly below atmospheric pressure</p> Signup and view all the answers

    What is transpulmonary pressure a measure of?

    <p>The pressure difference between alveoli and pleural pressure</p> Signup and view all the answers

    What is lung compliance defined as?

    <p>The extent to which the lungs expand for each unit increase in transpulmonary pressure</p> Signup and view all the answers

    What is the average total compliance of both lungs in a normal adult?

    <p>200 milliliters of air per centimeter of water</p> Signup and view all the answers

    During expiration, what is the alveolar pressure typically around?

    <p>+1 centimeter of water</p> Signup and view all the answers

    What does the compliance diagram of the lungs represent?

    <p>The elastic properties of the lung tissue for varying transpulmonary pressures</p> Signup and view all the answers

    What is the primary function of the negative pressure created in the thoracic cavity during inspiration?

    <p>To allow air to flow into the alveoli</p> Signup and view all the answers

    What happens to the pressure in the alveoli when air passages are blocked?

    <p>It attempts to collapse the alveoli.</p> Signup and view all the answers

    What is the calculated pressure in an average-sized alveolus lined with surfactant?

    <p>4 centimeters of water pressure.</p> Signup and view all the answers

    How does the radius of the alveolus affect the pressure caused by surface tension?

    <p>Pressure decreases as the radius increases.</p> Signup and view all the answers

    What is the pressure in an alveolus with a radius of 50 micrometers compared to one with a radius of 100 micrometers?

    <p>It is double the pressure.</p> Signup and view all the answers

    When does surfactant typically begin to be secreted into the alveoli during gestation?

    <p>Between the sixth and seventh months.</p> Signup and view all the answers

    What condition can occur in premature infants due to a lack of surfactant?

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

    What is the potential pressure difference in alveoli with little or no surfactant compared to those with normal surfactant levels?

    <p>They can exert up to six to eight times greater pressure.</p> Signup and view all the answers

    What treatment is particularly important for managing respiratory distress syndrome in newborns?

    <p>Properly applied continuous positive pressure breathing.</p> Signup and view all the answers

    Study Notes

    Respiratory System - Lung Physiology

    • The goals of respiration are to provide oxygen to tissues and remove carbon dioxide.
    • Pulmonary ventilation is the inflow and outflow of air between the atmosphere and lung alveoli.
    • Oxygen and carbon dioxide diffuse between alveoli and blood.
    • Oxygen and carbon dioxide are transported in blood to and from body tissues.
    • Respiration is regulated.

    Mechanics of Pulmonary Ventilation

    • Lung expansion and contraction occur through:
      • Downward and upward movement of the diaphragm, changing the chest cavity.
      • Elevation and depression of the ribs, altering the chest cavity’s anteroposterior diameter.
    • Normal breathing is primarily driven by diaphragm movement.
    • Inspiration: Diaphragm contracts, pulling lungs downward. Lungs expand, air flows in.
    • Expiration: Diaphragm relaxes, elastic recoil compresses lungs and expels air.
    • Additional force during heavy breathing comes from abdominal muscles.

    Muscles of Respiration

    • External intercostals are the primary muscles that raise the rib cage.
    • Sternocleidomastoid, anterior serrati, and scalene muscles assist in rib cage elevation.
    • Internal intercostals and abdominal muscles aid in rib cage depression.

    Pressures and Lung Movement

    • Pleural pressure is the pressure in the thin space between lung and chest wall.
    • Normal pleural pressure is slightly negative (-5 cm H₂O) to keep lungs inflated.
    • Expansion of the chest stretches the lungs and further reduces pleural pressure to about (-7.5 cm H₂O).
    • Alveolar pressure: Pressure inside the alveoli.
    • Inspiration: Alveolar pressure becomes slightly negative (below atmospheric pressure) to draw air into lungs.
    • Expiration: Alveolar pressure increases (above atmospheric pressure) to force air out of lungs.

    Lung Compliance

    • Lung compliance is the extent to which lungs expand for a given change in transpulmonary pressure.
    • Normal lung compliance is approximately 200 mL air per cm H₂O of transpulmonary pressure.
    • Compliance is determined by: 
      • Lung tissue elasticity.
      • Surface tension of fluid lining the alveoli.

    Surfactant

    • Surfactant is a substance produced by type II alveolar cells.
    • It reduces surface tension in the alveoli.
    • Reduced surface tension prevents alveolar collapse during exhalation.
    • Important for premature babies, as they often have underdeveloped surfactant production.

    Alveolar Interdependence

    • Alveoli are interconnected.
    • When one alveolus collapses, neighboring alveoli help keep it open by increasing their size.
    • This is crucial in preventing complete lung collapse.

    Reduced Lung Compliance Causes

    • Pulmonary fibrosis
    • Alveolar edema
    • Atelectasis
    • Hemo/pneumothorax

    Increased Lung Compliance Causes

    • Emphysema
    • Normal aging
    • Pulmonary emphysema

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    Physiology of Respiration Lec 3 PDF

    Description

    Test your knowledge on the respiratory system and lung physiology. Explore concepts such as pulmonary ventilation, gas exchange, and the mechanics of breathing. This quiz covers the essentials of how our lungs function and the muscles involved in respiration.

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