Respiratory system

Definition

The anatomical structures and physiological mechanisms that enable gas exchange between an organism and its environment, supplying oxygen for cellular respiration and removing carbon dioxide. In arthropods, this encompasses diverse adaptations including the tracheal system of insects and some arachnids (with spiracles, tracheae, and tracheoles), book lungs in arachnids such as spiders and scorpions, and various aquatic modifications like tracheal gills or plastrons.

Etymology

From Latin respirare 'to breathe, blow back' and systema 'organized whole'

Example

A diving beetle's respiratory system includes a plastron—a layer of trapped air held by hydrophobic hairs—that functions as a physical gill, allowing gas exchange underwater without surfacing.

Synonyms

• ventilatory system

Related Terms

• tracheal system
• Spiracle
• book lung
• cutaneous respiration
• Gas exchange
• Tracheole
• Plastron
• Hemolymph
• metabolic rate

Usage Notes

Arthropod respiratory systems are radically different from vertebrate lungs and are often studied as convergent evolutionary solutions to terrestrial respiration. The term encompasses both the anatomical structures and the physiological process; specialists may distinguish 'respiratory apparatus' (structures only) from 'respiratory function' (gas exchange process). In insects, the tracheal system is sometimes called the respiratory system in full, though strictly it is one component. Aquatic and parasitic arthropods show extensive modifications: some insect larvae have tracheal gills, while endoparasites may rely on cutaneous respiration through the body wall.