Breathing
How is the air sucked into and pushed out of our lungs ?
Breathing in (inhaling) |
Breathing out (exhaling) |
the chest moves upwards and outwards because the intercostal muscles contract |
the chest moves downwards and inwards because the intercostal muscles relax |
the diaphragm contracts and becomes flat |
the diaphragm relaxes and returns to ist dome-shape |
chest cavity is made bigger |
chest cavity is made smaller |
the pleural membranes attached to the ribs and lungs are moved outwards too |
the pleural membranes attached to the ribs and lungs are moved inwards too |
the lung volume increases and the air pressure in the lungs falls
air is sucked into the lungs |
the volume is reduced and the air pressure in the lungs increases
air is pushed out of the lungs |
The movement of the intercostal muscles and the diaphragm take place at the same time. At rest the up and down movements of the diaphragm are often all that is neeeded to move enough air into and out of the lungs. Only when you exercise and more oxygen is needed the intercostal muscles contract and move your ribcage upwards and outwards so that the lungs volume increases.