4. The spiracles can open and close like valves, allowing gas exchange but also reducing water loss.
5. The smallest of the branching tubes are called tracheoles and are in contact with the tissues. The end of each tracheole contains a small amount of fluid in which the gases dissolve.
6. When tissues such as muscles are active, the o fluid is drawn into the tissue, supplying oxygen.
7. The fluid is released back into the tracheole when the muscle is at rest, thereby moving the waste, carbon dioxide. 8. The tracheal system provides the insect with a large surface area for exchange of gases.
9, Small insects can rely on diffusion through the tracheal system alone to get gases in and out of the tissues.
10. Larger or more active insects ventilate their tracheal system by rhythmical body movements that pump air in and out
11. The mechanism of respiration in insects involves the following