How respiration takes place in cockroach?

Explanation

1. The respiratory system of cockroach is well developed compared with other terrestrial insects.
2. Branched tubes known as trachea open through 10 pairs of small holes called spiracles or stigmata, present on the lateral side of the body.
3. Terminal branches of tracheal tubes are called tracheoles which carry oxygen to the entire body. The spiracles open and close by valves regulated by sphincter or spiracular muscles. Each tracheole is filled with a watery fluid through which exchange of gases takes place.
4. During high muscular activity, a part of the fluid is drawn into the tissues to enable more oxygen intake and rapid diffusion.
5. The passage of air in the tracheal system is:
`"SPIRACLES "to "TRACHEA"`
`"TISSUES " leftarrow "TRACJEOLES"`