The process of breathing

The process of breathing

1. During breathing, all the parts of the thorax change during inhilation and exhilation

2. DURING INHILATION

   • These movements increase the volume of the chest and cause a slight drop in pressure in the thorax
     • Air then enters the lungs
   • External intercostal muscles CONTRACT pulling the ribs up
     • Internal intercostals RELAX
   • Diaphragm CONTRACTS, pulling down into a flatter shape

3. DURING EXHILATION

   • External intercostal muscles RELAX pulling the ribs down and in
     • Internal intercostals CONTRACT
   • Diaphragm RELAXES and returns to its normal domed shape
   • The chest volume decreases and the pressure in the thorax is raised slight above atmospheric pressure
     • The difference in pressure forces air out of the lungs

4. There are two movements that bring about ventilation: the movement of the ribs and the diaphragm