Breathing

• Inhalation:

  1. Diaphragm muscle contracts and flattens
  2. [RICE] 8Internal intercostal muscles relax, external intercostal muscles contract. Ribs move upwards and outwards. Sternum moves up and further from backbone.
  3. Volume of thorax and lungs increases, lungs expand and air pressure inside decreases
  4. Atmospheric pressure is higher than pressure in lungs. Air is forced in.
• Exhalation::

  1. Diaphragm muscle relaxes and arches upwards
  2. [ERIC] external intercostal muscles relax, internal intercostal muscles contract. Ribs move downwards and inwards. Sternum returns to its original position.
  3. Volume of thorax decreases, lungs are compressed and air pressure inside increases as volume decreases
  4. Pressure in lungs are higher than atmso pressure. Air is forced out of lungs until air pressure in lungs and A.P is equal.