Biology / Unit 13 Bio 3149 short lesson, about 20 seconds
Tracheal System in Insects
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The idea
An insect's tracheal system delivers air directly to tissues through branching tubes opening at external spiracles, exchanging gases without relying on blood at all.
In practice
Fine tracheole branches reach individual muscle cells directly, bypassing the circulatory system for oxygen delivery.
Where people slip
A tracheal system still limits body size, since diffusion through air-filled tubes only reaches so far into a large body.
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