L7B: Respiratory system (mechanisms of breathing)

• What does external respiration involve?

  Exchange of oxygen and carbon dioxide
• What is atmospheric pressure?

  Combined pressure of air mixture
• How is gas pressure measured?

  With a barometer
• What is partial pressure?

  Pressure exerted by a single gas
• What does Dalton's Law state?

  Different gases exert different partial pressures
• When does the percentage of partial pressure change?

  When the gas mixture is changed
• How can partial pressure change?

  With changes in altitude
• How do gases move in relation to pressure?

  From higher pressure to lower pressure
• What are the two main components of ventilation?

  • Inspiration
  • Expiration
• What type of process is inspiration?

  Always an active process
• What is the major inspiratory muscle?

  The diaphragm
• What aids the diaphragm during vigorous exercise?

  Accessory muscles like sternocleidomastoid
• What happens to the chest cavity during inspiration?

  It increases in size, reducing pressure
• How is expiration characterized at rest?

  It is a passive process
• What happens to pressure inside the lungs during expiration?

  It increases, allowing air to leave
• What occurs to the lung parts during expiration?

  They recoil after being stretched
• What muscles are used for forced expiration?

  Abdominal and internal intercostal muscles
• What is intrapleural pressure?

  Pressure in the pleural cavity
• What is transpulmonary pressure?

  Difference between intrapulmonary and intrapleural pressure
• What is intrapulmonary pressure?

  Pressure inside airways and alveoli
• How does chest expansion affect intrapleural pressure?

  It decreases intrapleural pressure
• What happens to intrapulmonary pressure during lung expansion?

  It falls below atmospheric pressure
• What occurs during expiration regarding lung volume?

  The volume of lungs decreases
• What is lung compliance?

  Ease of inflating the lungs
• What factors affect lung compliance?

  Elasticity and surface tension
• What role do elastic fibers play in the lungs?

  Allow easy stretching of the lungs
• What happens when elastic fibers are replaced with scar tissue?

  Compliance is reduced
• What causes surface tension in alveoli?

  A thin film of liquid in alveoli
• What happens to smaller alveoli without surfactant?

  They collapse into larger alveoli
• What do surfactant molecules do?

  Disrupt surface tension buildup
• How does surfactant affect compliance?

  Increases compliance by reducing surface tension
• Where is the smallest airway resistance found?

  In bronchioles and alveoli
• How is airflow related to resistance?

  Inversely related to resistance
• What are tidal volume (TV) and its significance?

  Air moved during normal breathing
• What is inspiratory reserve volume (IRV)?


  Max air taken in after tidal volume
• What is expiratory reserve volume (ERV)?

  Max air expelled after tidal volume
• What is residual volume (RV)?

  Air that cannot be forced out of lungs
• How are lung volumes measured?

  Using a spirometer
• What do FEV1 and FVC measure?

  Examples of pulmonary function studies
• What is forced vital capacity (FVC)?

  Full inspiration then forced maximal expiration