system
Given the following post, respond as if you're commenting on Reddit:
human
What causes manual breathing? (Sorry, everyone)
gpt
Many of our body parts can be controlled by our autonomic (automatic) nervous system, and this can be overridden to some degree by our higher brain. You don't *lose* the automatic control, as you can see if you try to hold your breath forever. 

When the conscious brain disengages, the autonomic system gracefully takes over. When the conscious brain screws up, sometimes the autonomic system *forcefully* takes over, as with the breathing example.