Any sudden
action in response to some happening in the environment, is called as reflex
reaction. The general idea is that we react we react to such a situation
without thinking about it or without feeling in control of our reaction. Yet
these actions of ours are in response to the stimulus from our surrounding. At
this juncture we are forced to think : how is control and co-ordination
achieved in such a situation?
Let us try and
understand this in further detail by considering the following example.
Touching a vessel containing very hot tea is a dangerous situation for us. How
would we respond to a situation like this? one possible way is that we think
consciously about the pain and the possibility of getting wounded, and hence we
withdraw our hand. Now how long will it take for us to think and perform the
activity? If the messages (impulses) have to be sent about the way we have
discuss it earlier in the chapter, then it would take quite some time for us to
react in response to the situation. But the response to such situations are
quick and immediate.
Rather than having to think about the sensation of pain, if
the nerves that detect pain were to be connected to the nerves that bring about
the movement of the muscle, the action might be completed quickly. Nerves from
all over from the body meeting in a bundle in such a connection is commonly
called as the spinal cord. Hence reflex arcs are formed in the spinal cord,
although the messages reach the brain.
Reflex arcs are
perhaps evolved in animals because the thinking process of the brain is a bit
slow. In many animals, specially lower animals the complex neuron network needed
for thinking is not there or is not well developed. Hence reflex arcs have been
evolved as efficient ways of functioning in the absence of the true through
processes. However, in spite of the presence of complex neuron networks, reflex
arcs continue to be more efficient for quick responses.
