Why is it important to destroy the brain and spinal cord of a frog before conducting?

The spinal cord and the brain together comprise of the central nervous system. The spinal cord functions as a relay center for the reflex activities. The first thing the frog feels at the time of dissection is the sense of pain, and one cannot record the exact physiological reaction of the body towards the test compound.

As when one impart any stimulus, the central nervous system reacts instantaneously and starts safeguarding and reflex actions by discharging some of the chemical components and eliciting the movements of the body. The result of what one obtains in such case would not be entirely because of the test compound.

Thus, in order to inhibit the influence of the central nervous system on the contraction of the muscle, the brain and spinal cord of the frog should be destructed.