THE LUNGS

Inspiration and expiration

• Role of intercostal muscles = The brain sends nerve messages to the diaphragm to flatten it. Pleural membranes are attached the lungs to both the ribcage and diaphragm, so the movement of these structures allow the lungs to stretch and open the alveoli. This increases the internal volume of the lungs and allows air to rush into the lungs and inflating the alveoli
• Role of diaphragm = The brain stops sending signals to the ribs and diaphragm to stop them from contracting. The diaphragm recoils upwards, into its ribcages and causes it to drop back and downwards. This decreases the volume of the lungs and air pressure in the lungs increases above the pressure of atmospheric air and so air is forced out
• Role of pleural membranes = The pleural membranes are crucial to the lungs inflating and deflating as…