tracheán

Trachean refers to the tracheal system of respiration found in insects and other terrestrial arthropods. This system is a network of air-filled tubes that deliver oxygen directly to the body's tissues and remove carbon dioxide. The trachean system consists of a series of external openings called spiracles, which lead to internal tracheae. These tracheae branch into smaller and smaller tubules called tracheoles, which are fine enough to penetrate individual cells.

Oxygen enters the body through the spiracles and travels through the tracheae and tracheoles to reach the cells where it is used for cellular respiration. Carbon dioxide, a waste product of cellular respiration, diffuses from the cells into the tracheoles and then moves up through the tracheal system to be expelled from the body through the spiracles. The efficiency of the trachean system allows for high metabolic rates, which is crucial for many insect activities like flight.

The size and complexity of the trachean system can vary among different arthropod species, often correlating with their size and activity levels. In larger or more active species, the trachean system may be supplemented by muscular pumping movements or air sacs to improve ventilation. This direct gas exchange mechanism is a defining characteristic of many terrestrial invertebrates.