Inspiration

Expiration

1. It is an active process of intake of O₂.

1. It is a passive process of release of Co₂ from body.

2. It includes muscles contraction.

2. It involves relaxation of all muscles.

3. During it, Thoracic cavity increases in volume and it lowers the diaphragm.

3. During it, thoracic cavity reduces its volume and upwards the diaphragm.

4. External intercostals muscles move forward to let the air come inside lungs.

4. External intercostals muscles relax. So Lungs also contracts and relax.

5. No role of internal inter-costal muscles.

5. Abdominal and internal inter-costals muscles also called expiratory muscles also contract during expiration and move ribs downward and inward.

6. Lungs expand.

6. Lungs contracts.

7. Diaphragm lowers (downward direction).

7. Diaphragm upwards (upward direction).

8. Thoracic cavity increases it volume.

8. Thoracic cavity reduces its volume.

9. Ribs and sternum raised.

9. Ribs and sternum lowers to original position.