Why the brain sends a message to diaphragm and rib muscles telling them breathe when you hold your breathe?

When you hold your breath, the brain still sends messages to the diaphragm and rib muscles to breathe. This is because your body needs to maintain a constant exchange of oxygen and carbon dioxide in order to function properly.

The diaphragm and rib muscles are responsible for inhaling and exhaling, so they need to continue contracting and relaxing even if you are trying to hold your breath.

However, if you hold your breath for too long, the carbon dioxide levels in your blood will build up and the oxygen levels will drop, which can lead to dizziness, lightheadedness, and eventually fainting.