Respiratory System of Cockroach (Moderate)

Eight pairs of stigmata are present in the first eight abdominal segments.

From the atrium of each abdominal spiracle, three tracheal tubes arise. The three tracheal tubes are as follows: 

A. Dorsal tracheal tube
B. Ventral tracheal tube
C. Lateral tracheal tube

In a cockroach, stigmata are absent in the prothorax, 9^th and 10^th abdominal fragments.

Taenidia present in trachea prevent the collapse of trachea.

Rapid release of CO₂ in the atmosphere takes place in the open phase. During the open phase, spiracular muscles relax and the spiracles open completely.

The oxidative damage hypothesis states that discontinuous gas exchange cycles are an adaptation to reduce the amount of O₂ delivered to tissues under periods of low metabolic rate.

In cockroaches, respiratory movements are controlled and coordinated by the nervous system.

This statement is incorrect. Expiration is an active process.

Each spiracle is surrounded by a ring-like sclerite called peritreme.

The lateral longitudinal tracheal trunks are the longest tracheal trunks.

Cockroaches have adapted to tracheal breathing in order to conserve water. Tracheae do not just carry air inwards to the cells, they also carry water out of the cells. The hypothesis is that when cockroaches are resting and have a lower oxygen requirement, they close the spiracles in order to conserve water.

In a cockroach, the muscles which help in respiration are called tergo-sternal muscles.

Intima is the inner chitinous layer of trachea.

In holopneustic arrangement, there are 10 pairs of spiracles with 1 mesothoracic, 1 metathoracic and 8 abdominals. Such an arrangement is found in a cockroach.

During inspiration, thoracic spiracles are kept open and the abdominal spiracles are kept closed.