system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do we (and other chordates, for that matter) have our respiratory organs on our head instead of torso, which would make a shorter path to lungs?

Also, why have a centralized respiratory system with lungs and a single airway in the first place instead of having many breathing holes all over the body, like insects do?
gpt
Interesting question.  Openings to the body create other issues, one being the maintenance of a sterile environment inside the body.  All of them can be pathways for infection to enter the body.  The respiratory "tree" is lined with cilia that move mucus up to the throat, then it is swallowed into the stomach, where stomach acid kill any bacteria.

Also, having a single airway allows us to use the air for speech generation (larynx), which has been vital in the development of human culture, but also important for almost all chordates.  Having some dead space in the respiratory tree also allows for the air to be warmed as we inhale and for decreasing respiratory water losses due to evaporation.  Consider also that we use the same upper airway system (well, the oropharynx anyway) for eating and drinking, which minimizes the number of openings to the outside.