Science 1.3 breathing

• Respiration


  1. Breathing

  2. Inhale air

  3. Exhale air
• Breathing


  • Aided by diaphragm
  • Process of taking in air into our bodies and giving it out again
• Inspiration

  Active process brought about by ribs, intercostal muscles, sternum and diaphragm
• Inspiration


  1. Intercostal muscles contract, pulling ribs outward

  2. Diaphragm contracts, becomes almost flat

  3. Volume of thoracic cavity increases, pressure on lungs decreases

  4. Lungs expand, atmospheric air rushes in
• Expiration


  • the intercostal muscles will relax and go back to normal
• Expiration


  1. Intercostal muscles relax, pulling ribs inwards

  2. Diaphragm relaxes, becomes dome shaped

  3. Volume of thoracic cavity decreases, pressure on lungs increases

  4. Air in lungs rushes out
• Alternate inspiration and expiration together form the respiratory cycle
• Breathing is under the control of the medulla oblongata of the brain