Respiration in cockroach is performed by the contraction & the relaxation of the tergosternal muscles. As a result of the contraction of the tergosternal muscles, the air squeezed out which is called as expiration. The relaxation of the tergosternal muscles reduces the pressure on the trachea, as air result the air rushes into the body through the spiracles. It is called as inspiration. During rest the process of breathing in involuntary & during active phase, it a voluntary process. The exchange of gases takes place by diffusion between the trachiole fluid & tissue fluid.
