system
Given the following post, respond as if you're commenting on Reddit:
human
If someone is paralyzed from the neck down, how can they still breathe or have a heartbeat?

If the spinal cord is damaged to the point where a person cannot use their arms or legs, why can their heart an lungs still function? Are they connected to the brain in a different way?
gpt
First, your heart does not need any nerve signals from your spinal cord in order to function.  The heart will beat on its own regardless of the status of the spinal cord.  

Next, you do need nerve signals from the upper cervical spinal cord (C1-C4) in order for your diaphragm to contract and for you to breathe.  If the spinal cord in this part of the cervical spinal cord is completely transected (cut), you will not be able to breathe on your own - either you'll die from the injury or you'll need a respirator to mechanically push air into your lungs for the rest of your life.  

The lower cervical spinal cord (C5-C8) gives rise to most of the motor innervation of your arms and hands.  A spinal cord injury in this part of the cervical spinal cord will impair the use of the arms and hands.  

So, it's entirely possible for a person to have a spinal cord injury that is below the part of the cervical spinal cord that innervates the diaphragm (C1-C4) yet is still above the part of the spinal cord that innervates the arms and hands (C5-C8) - this person will be able to breathe on their own, but will be unable to normally control their arms, hands, or any other voluntary muscles below the level of the neck.