How does a reflex arc to protect the human body from danger?

Well, the reflex arc causes our body to react almost immediately when our body, that is our sensory structures sense danger. In short it causes a reflex action...like when you touch a hot pan and not even a second after you remove your hand because it is too hotAll that is because a signal has travelled from the neurons in your hand via a network of them (in the shortest way) until reaching your brain which gives a signal back causing the muscles in your hand to retract back and thus move your hand away. Hope that this answer will help you.