all voluntary and sensory abilities are controlled and/or processed by the brain, as well as certain involuntary actions like consciousness, sleep, and breathing. because of the last bit, technically everything needs the brain because breathing provides oxygen, which is needed to produce energy for all cells to function.
certain involuntary actions don't necessarily require the brain though, like the beating of your heart, which has its own electrical system that lets it keep beating without input from the brain. however, the brain does regulate and modify it when necessary, like when you're scared and your heart rate goes up. there's probably a few more that i can't think of off the top of my head, but short answer is pretty much everything.
CyraFen t1_j6mtnuc wrote
Reply to Eli5: what does the brain control in the body? by Parking_Tale7916
all voluntary and sensory abilities are controlled and/or processed by the brain, as well as certain involuntary actions like consciousness, sleep, and breathing. because of the last bit, technically everything needs the brain because breathing provides oxygen, which is needed to produce energy for all cells to function.
certain involuntary actions don't necessarily require the brain though, like the beating of your heart, which has its own electrical system that lets it keep beating without input from the brain. however, the brain does regulate and modify it when necessary, like when you're scared and your heart rate goes up. there's probably a few more that i can't think of off the top of my head, but short answer is pretty much everything.