Ventilation

• What is ventilation?

  Movement of air into and out of lungs
• What are the two main components of ventilation?

  Inspiration and expiration
• What does ventilation provide to the body?

  Oxygen and removes carbon dioxide
• What is the thoracic cavity?

  The cavity where the lungs are located
• What role do muscles play in ventilation?

  They change the volume of the thoracic cavity
• What is the diaphragm?

  A sheet of muscle involved in ventilation
• What happens when the diaphragm contracts?

  It moves the ribcage up and out
• What do external intercostal muscles do?

  Pull the ribcage up and out
• What do internal intercostal muscles do?

  Pull the ribcage down and in
• How do external and internal intercostal muscles differ?

  They have opposite effects on the ribcage
• What is inspiration?

  An active process requiring energy
• What happens during inspiration?

  Ribcage moves up, diaphragm contracts
• What occurs to lung pressure during inspiration?

  Lung pressure decreases below atmospheric pressure
• What is expiration?

  A passive process at rest
• How can expiration be forced?

  By contracting internal intercostal muscles
• What happens during normal expiration?

  Ribcage moves down, diaphragm relaxes
• What occurs to lung pressure during expiration?

  Lung pressure increases above atmospheric pressure
• What role do elastic fibers in the alveoli play during expiration?

  They shrink and recoil to push air out
• How does the thoracic cavity volume change during expiration?

  The volume decreases
• What is the pressure gradient in relation to ventilation?

  Air flows from high to low pressure
• What are the steps involved in inspiration?

  1. External intercostal muscles contract
  2. Internal intercostal muscles relax
  3. Ribcage moves up and out
  4. Diaphragm contracts and flattens
  5. Thoracic cavity volume increases
  6. Lung pressure decreases
  7. Air flows into lungs
• What are the steps involved in expiration?

  1. External intercostal muscles relax
  2. Ribcage moves down and in
  3. Diaphragm relaxes and unflattens
  4. Thoracic cavity volume decreases
  5. Lung pressure increases
  6. Air is forced out of lungs
  7. Elastic fibers recoil to aid expiration
• What does oxygen uptake measure?

  Volume of oxygen used in a given time
• How can breathing measurements be made?

  Using a spirometer
• What happens to carbon dioxide in a spirometer?

  It is absorbed by soda lime
• Why is carbon dioxide absorbed in a spirometer?

  To prevent respiratory distress
• What is created as the subject breathes through the spirometer?

  A trace on a rotating drum or digital graph
• What is vital capacity in breathing measurement?

  Maximum volume of air in one breath
• What is tidal volume?

  Volume of air during normal breathing
• How is breathing rate defined?

  Number of breaths taken in one minute
• What can be calculated from the spirometer trace?

  Vital capacity, tidal volume, and breathing rate
• How is oxygen uptake measured using a spirometer?

  By observing the decrease in air volume
• What is the residual volume?

  Air retained in the lungs after exhalation
• What does the residual volume indicate?

  Volume of air left after maximum exhalation
• What are the main measurements taken using a spirometer?

  • Vital capacity
  • Tidal volume
  • Breathing rate
  • Oxygen uptake
• What is the process of measuring breathing with a spirometer?

  1. Subject breathes in and out through the spirometer
  2. Carbon dioxide is absorbed by soda lime
  3. A trace is drawn or a digital graph is created
  4. Measurements like vital capacity and tidal volume are calculated
  5. Oxygen uptake is measured by volume change