Reflex is a word we use very commonly when we talk about some sudden action In response to something in the environment. A common idea is that we do something without thinking about it or without feeling in control of a reaction.
Take example of touching a flame, which is an urgent and dangerous situation for us, or in fact for any animal. How would be respond to this? There are two choices either we can wait to feel the pain and think how to react, but then we would have got burn or we could think for a sudden action. Now how our body can perform a sudden action without thinking about it? The answer depends on how we think, as thinking is a complex action. In this case it is no surprise that the thinking tissue in a body consists of dense networks of interactively arrange neurones. It is present in the forward end of the skull and receives signals from all over the body, which it thinks about before responding to them. Obviously in order to receive these signals, this thinking part of the brain in the skull must be connected to nerves coming from various parts of the body. Similarly if this part of the brain is instructing muscles to move, nerves must carry the signal back to different parts of the body if all of this is to be done when we touch hot object it may take enough time for us to get burn.
So rather than thinking about the sensation of heat if the nerves that feel heat, is connected to the nerves that move muscles in a simpler and quicker way the process of catching the signal of burn and responding to it by an quick and effective action might be completed quickly such a connection is commonly called a reflex action.