In our bodies the <em><u>second line of defense</u></em> includes active immunity. It contains non-specific immune responses, but yet still contains specific responses for certain things such as inflammatory and fevers.
The answer is reflex action. Impulse that triggers a reflex action does not pass through the brain so as to shorten the time for response. It passes through a reflex arch and this is why the muscles are contracted even without time to think of what happened. The sensory and motor neurons only arch at the spinal cord.