Respiratory Physiology Quiz
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Questions and Answers

What primarily determines the elastic behavior of the lungs?

  • Airway pressure during ventilation
  • Elastic connective tissue and alveolar surface tension (correct)
  • Muscular contraction of the diaphragm
  • Volume of the lungs at rest

    • What is described as the stretchability of the lungs?

  • Alveolar pressure
  • Elastic recoil
  • Resilience
  • Compliance (correct)

    • What condition is characterized by decreased lung compliance?

  • Pneumonia
  • Pulmonary fibrosis (correct)
  • Asthma
  • Chronic bronchitis

    • What factor does elastic recoil of the lungs depend on?

    <p>Connective tissue and alveolar surface tension</p> Signup and view all the answers

    What do we call a lung that lacks normal stretchability?

    <p>Stiff lung</p> Signup and view all the answers

    What percentage of surfactant DPPC is typically recycled back into type II pneumocytes?

    <p>90%</p> Signup and view all the answers

    What is a primary cause of respiratory distress syndrome (RDS) in newborns?

    <p>Deficiency of surfactant</p> Signup and view all the answers

    Which of the following surfactant treatments is derived from cow lung?

    <p>Surfactant TA</p> Signup and view all the answers

    How does vaginal delivery contribute to surfactant production in premature lungs?

    <p>By increasing cortisol production</p> Signup and view all the answers

    Which of the following medications is a synthetic pulmonary surfactant?

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

    What role does nitric oxide (NO) play in human physiology?

    <p>It's a signaling molecule</p> Signup and view all the answers

    What is one of the therapeutic uses of surfactant in newborns?

    <p>To treat respiratory distress syndrome</p> Signup and view all the answers

    Which substance reduces surface tension in the lungs to prevent collapse?

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

    What is the main function of lamellar bodies in the lungs?

    <p>Storage and secretion of surfactant</p> Signup and view all the answers

    At what developmental stage do lamellar bodies first appear in the cytoplasm?

    <p>About 20 weeks gestation</p> Signup and view all the answers

    What structure do lamellar bodies transform into after being secreted into the alveolar lining fluid?

    <p>Tubular myelin</p> Signup and view all the answers

    Which surfactant protein plays a crucial role in the formation of tubular myelin?

    <p>SP-A</p> Signup and view all the answers

    What is the estimated amount of surfactant stored in full-term infants?

    <p>100 mg/kg</p> Signup and view all the answers

    What happens to surfactant during the process of alveolar respiration?

    <p>It gets recycled by type II cells</p> Signup and view all the answers

    What happens to surfactant phospholipids in the alveolar space?

    <p>They form tubular myelin structures</p> Signup and view all the answers

    What is the estimated amount of surfactant present in preterm infants at birth?

    <p>4–5 mg/kg</p> Signup and view all the answers

    What is the primary role of pulmonary surfactant in the alveoli?

    <p>It lowers the alveolar surface tension.</p> Signup and view all the answers

    Which substance constitutes the majority of pulmonary surfactant?

    <p>Dipalmitoyl phosphatidylcholine (DPPC)</p> Signup and view all the answers

    What effect does pulmonary surfactant have on lung compliance?

    <p>It increases lung compliance.</p> Signup and view all the answers

    What composition primarily includes surfactant proteins?

    <p>Apolipoproteins and surfactant proteins</p> Signup and view all the answers

    Why is the fluidity of surfactant important for its function?

    <p>It enhances the adsorption capacity at the air-water interface.</p> Signup and view all the answers

    What is one of the defense roles of pulmonary surfactant?

    <p>It provides defense against infection and inflammation.</p> Signup and view all the answers

    How does pulmonary surfactant affect the likelihood of lung collapse?

    <p>It reduces the tendency of the lungs to recoil.</p> Signup and view all the answers

    What property of dipalmitoyl phosphatidylcholine (DPPC) makes it particularly suitable for surfactant function?

    <p>Its amphipathic behavior.</p> Signup and view all the answers

    What role do collectins, such as SP-A and SP-D, serve in the immune system?

    <p>They promote phagocytosis by macrophages.</p> Signup and view all the answers

    Which component of surfactant is primarily responsible for increasing the spread of surfactant over the surface of the lungs?

    <p>SP-C</p> Signup and view all the answers

    What happens to individuals born without SP-B?

    <p>They develop intractable respiratory failure.</p> Signup and view all the answers

    How are SP-B and SP-C processed in the cell before being secreted into the alveolar airspaces?

    <p>They pass through the Golgi and late endosome.</p> Signup and view all the answers

    What structural feature distinguishes the protein SP-A in the collectin family?

    <p>A collagen domain fused to a lectin domain</p> Signup and view all the answers

    Which proteins are crucial for the proper biophysical function of the lung surfactant?

    <p>SP-B and SP-C</p> Signup and view all the answers

    What is the primary result of lacking surfactant protein SP-C?

    <p>Individuals develop progressive interstitial pneumonitis.</p> Signup and view all the answers

    During which stage of lung development does surfactant production begin in humans?

    <p>Alveolar sac stage</p> Signup and view all the answers

    What is meant by lung compliance?

    <p>The change in lung volume per unit change in airway pressure</p> Signup and view all the answers

    Which factor contributes to elastic recoil in the lungs?

    <p>The presence of elastin fibers in connective tissue</p> Signup and view all the answers

    How does pulmonary fibrosis affect lung compliance?

    <p>It decreases lung compliance due to replacement of normal lung tissue with fibrous tissue</p> Signup and view all the answers

    What role does alveolar surface tension play in the elastic behavior of the lungs?

    <p>It contributes to the elastic recoil of the lungs</p> Signup and view all the answers

    What happens to the lungs during expiration?

    <p>The lungs recoil to return to their original position</p> Signup and view all the answers

    What role do the carbohydrate recognition domains of collectins play in the immune response?

    <p>They promote phagocytosis by macrophages.</p> Signup and view all the answers

    How many trimers assemble to form the mature SP-A protein?

    <p>6 trimers</p> Signup and view all the answers

    What is the consequence for humans born without surfactant protein SP-C?

    <p>Onset of progressive interstitial pneumonitis.</p> Signup and view all the answers

    In which cells does surfactant production begin during lung development?

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

    What type of proteins are SP-B and SP-C classified as?

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

    What happens to SP-B and SP-C after they are synthesized in type II cells?

    <p>They are stored in lamellar bodies until secreted.</p> Signup and view all the answers

    Which structural region of SP-A contributes to its classification as a collectin?

    <p>Lectin domain</p> Signup and view all the answers

    Which protein is primarily responsible for facilitating surfactant dynamics and spreading over the lung surface?

    <p>SP-B</p> Signup and view all the answers

    What is the primary function of surfactant in the alveoli?

    <p>Decrease surface tension</p> Signup and view all the answers

    What type of cells are responsible for secreting surfactant?

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

    What structural feature is essential for the alveoli to maintain proper gas exchange?

    <p>Air-blood barrier that is 1 cell thick</p> Signup and view all the answers

    How does surfactant influence the effort required to breathe?

    <p>It reduces surface tension, decreasing breathing effort.</p> Signup and view all the answers

    What would likely occur if the surfactant in the alveoli were absent?

    <p>Increased collapse of alveoli due to high surface tension</p> Signup and view all the answers

    Which statement best describes the proportion of inspired air that is exchanged during respiration?

    <p>Approximately 85% of inspired air is retained in the respiratory tract.</p> Signup and view all the answers

    Which component helps to maintain the structural integrity of alveoli during exhalation?

    <p>Elastic connective tissue</p> Signup and view all the answers

    Why does the presence of surfactant improve gas exchange efficiency in the alveoli?

    <p>It lowers surface tension, allowing alveoli to expand more easily.</p> Signup and view all the answers

    What is the main benefit of pulmonary surfactant in the alveoli?

    <p>It decreases the surface tension in the alveoli.</p> Signup and view all the answers

    Which component primarily contributes to the fluidity of pulmonary surfactant?

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

    How does pulmonary surfactant help prevent the collapse of alveoli?

    <p>By lowering the alveolar surface tension.</p> Signup and view all the answers

    What percentage of pulmonary surfactant consists of surfactant proteins?

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

    Which of the following is a key function of pulmonary surfactant aside from lowering surface tension?

    <p>Stabilizing the alveoli.</p> Signup and view all the answers

    What is the primary lipid found in pulmonary surfactant?

    <p>Dipalmitoyl phosphatidylcholine (DPPC)</p> Signup and view all the answers

    What role do surfactant proteins SP-A and SP-D play in the lungs?

    <p>Play a role in immune defense.</p> Signup and view all the answers

    What are lamellar bodies primarily involved in during surfactant production?

    <p>Storing and processing surfactant</p> Signup and view all the answers

    What is tubular myelin primarily formed from?

    <p>Lipid bilayers from lamellar bodies</p> Signup and view all the answers

    What role does surfactant protein SP-A play in tubular myelin formation?

    <p>Facilitates lipid insertion into membranes</p> Signup and view all the answers

    How are lamellar bodies secreted into the alveolar lining fluid?

    <p>Via exocytosis</p> Signup and view all the answers

    What happens to surfactant during repeated lung contractions?

    <p>It yields unilamellar small aggregates</p> Signup and view all the answers

    At what gestational age do lamellar bodies first appear in the cytoplasm?

    <p>20 weeks</p> Signup and view all the answers

    What is the primary function of tubular myelin in the lungs?

    <p>To act as a reservoir of surfactant</p> Signup and view all the answers

    What is the significance of cortisol administration to pregnant mothers at risk of preterm delivery?

    <p>It enhances surfactant production in the lungs.</p> Signup and view all the answers

    Which of the following statements about surfactant recycling is true?

    <p>10% of the surfactant is eliminated by macrophages.</p> Signup and view all the answers

    What is primarily responsible for the higher incidence of respiratory distress syndrome in babies delivered by cesarean section?

    <p>Lower cortisol levels due to absence of birth stress.</p> Signup and view all the answers

    How does the composition of synthetic pulmonary surfactants compare to animal-derived surfactants?

    <p>Synthetic surfactants often include spreading agents not found in animal-derived types.</p> Signup and view all the answers

    What is the primary function of pulmonary surfactant in the lungs?

    <p>To reduce surface tension and prevent alveolar collapse.</p> Signup and view all the answers

    What is a likely consequence of a deficiency in surfactant in newborns?

    <p>High risk of lung collapse and respiratory distress syndrome.</p> Signup and view all the answers

    Which statement accurately describes the treatment options for newborns with respiratory distress syndrome?

    <p>Both corticosteroids and surfactant treatments can be used.</p> Signup and view all the answers

    What gas is described as having no known cellular storage mechanism in humans?

    <p>Nitric Oxide.</p> Signup and view all the answers

    Which type of alveolar cell is responsible for secreting surfactant?

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

    What percentage of inspired air remains in the respiratory tract during the next cycle of expiration and inspiration?

    <p>85%</p> Signup and view all the answers

    What type of epithelium comprises the alveoli?

    <p>Simple squamous epithelium</p> Signup and view all the answers

    What effect does surfactant have on alveolar expansion and contraction?

    <p>Enables more effective gas exchange</p> Signup and view all the answers

    The 'air-blood' barrier in the alveoli is primarily composed of what?

    <p>One cell thick lining plus a basement membrane</p> Signup and view all the answers

    Why is it difficult for alveoli to re-open after being collapsed?

    <p>Due to high surface tension caused by the fluids lining the alveoli</p> Signup and view all the answers

    What role do elastic connective tissues play in the lungs?

    <p>Aid in passive exhalation</p> Signup and view all the answers

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