The Breathing System
When we breathe, air moves into and out of our body. There are two movements involved in the process of breathing: 1. Inspiration (also known as inhalation) – This is breathing air into the body. When we inspire: The intercostals muscles found between the ribs contract. This raises the ribs upwards and outward expanding the ribcage diaphragm contracts and flattens, pulling downwards. The result is that the thorax increases in volume, which in turn lowers the pressure inside it and consequently air is sucked into the lungs. 2. Expiration (also known as exhalation) – This is breathing air out of our body. When we expire: The intercostal muscles relax. This lowers the ribs downwards and inwards. The diaphragm relaxes, moving back upwards. The result is that the thorax decreases in volume, which in turn increases the pressure inside it and consequently forces air out of the lungs.