Breathing

• What is the scientific term for "breathing"?

  Ventilation
• What occurs during inspiration?

  Air pressure in the atmosphere is greater
• What happens during expiration?

  Air pressure in the lungs is greater
• What is required for ventilation to occur?

  • Pressure changes in the lungs
  • Movement of two sets of muscles
• What muscle separates the thorax from the abdomen?

  The diaphragm
• Where are the intercostal muscles located?

  Between the ribs
• What are the two sets of intercostal muscles?

  • Internal intercostal muscles
  • External intercostal muscles
• What is the function of internal intercostal muscles?

  They lead to expiration
• What is the function of external intercostal muscles?

  They lead to inspiration
• What happens to the diaphragm during inspiration?

  • Contracts
  • Moves downwards from domed position
• What happens to the diaphragm during expiration?

  • Relaxes
  • Returns to domed position
• What changes occur in lung volume during inspiration and expiration?

  • Inspiration: Lung volume increases
  • Expiration: Lung volume decreases
• What is the relationship between air pressure and air movement during ventilation?

  • Inspiration: Air moves inwards as pressure decreases
  • Expiration: Air moves outwards as pressure increases
• What is pulmonary ventilation?

  Total volume of air moved in one minute
• How is pulmonary ventilation calculated?

  By multiplying tidal volume and breathing rate
• What is tidal volume?

  Volume of air taken at each breath
• What is the typical tidal volume at rest?

  0.5 dm³
• What is the normal breathing rate for a healthy adult?

  12-20 breaths per minute
• What is the formula for pulmonary ventilation?

  • Pulmonary ventilation = tidal volume x breathing rate
  • Units: dm³min⁻¹
• How is tidal volume measured?

  • Using a spirometer
  • Air-tight chamber with a perspex lid
  • Person breathes in and out
• What does a spirometer trace measure?

  Volume of air breathed in and out
• What is vital capacity?

  Maximum volume of air breathed out
• What is forced expiration volume (FEV)?

  Volume of air breathed out in one second
• What are the components of a spirometer setup?

  • Arm and pen attached to chamber lid
  • Revolving drum for trace
  • Air-tight chamber filled with oxygen
  • Soda lime canister to remove CO₂