Breathing and Gas Exchange

• What happens during inhalation?


  1. Intercostal muscles contract
  2. Ribcage moves up and out
  3. Diaphragm contracts and flattens
  4. Volume of the thorax increases while pressure decrease

  (OPPOSITE FOR EXHALATION)
• Describe how gases are exchanged at the alveoli

  1. Inhalation occurs
  2. Oxygen arrives at the alveoli (an air sac)
  3. The high concentration of oxygen diffuses through the thin walls and into the capillary
• Adaptations of the alveoli:

  • Large surface area
  • Thin cell wall
  • Good supply of blood capillaries to maintain concentration gradient
• Gas Exchange System:

  A) Nose

  B) Mouth

  C) Trachea

  D) Bronchus

  E) Diaphragm

  F) Intercostal Muscles

  G) Rib

  H) Lung

  I) Heart

  J) Bronchioles

  K) Alveoli

  L) Abdomen

  M) Thorax