The brain

The brain is protected inside the skull.

Because it controls everything we do. If it was injured our bodies could not function properly.

By means of nerves.

Your body needs to react quickly in order to keep you safe/healthy. In this case your brain makes you move fast to get out of the way of the car.

Your brain allows you to move so that you can pick up the phone and selct the number; it lets you see what you are doing; it lets you hear the phone ringing and your friend's voice; it lets you talk to your friend.