inspiration

• 1. the external intercostal muscles and diaphragm contract
• 2. this causes the ribcage to move upwards and outwards, and the diaphragm to flatten, increasing the volume of the thoracic cavity
• 3. as the volume of the thoracic cavity increases, lung pressure decreases
• 4. air will flow from an area of higher pressure to an area of lower pressure, so air flows down the trachea and into the lungs
• 5. inspiration is an active process - it requires energy
• diaphragm contracts and becomes flat and external intercostal muscles contract. increases the volume of the thoracic cavity and decreases the pressure. pressure gradient is created and air moves down the pressure gradient into the lungs