Explain the process of inhalation

Inhalation is the process of breathing air into the lungs through the nose and mouth. This causes an increase in the volume of air in the lungs, meaning the pressure will decrease. This is acheived using 3 sets of muscles. The internal and external intercostals lie between the ribs; the internal relax whilst the external contract, which pulls the ribcage up and out. The diaphragm, the sheet of muscle between the lungs and the abdomen, also contracts, pulling the ribcage downwards. Both these actions together help push air into the lungs.