Living beings show movements to get some advantage based on changes around their environment. All movements in response to changes in environment are controlled by Brain. Nervous System: Information around us are sensed nerve cells. Information collected at dendrite tip of nerve cells cause chemical reaction which create electric impulse. This impulse travels from the dendrite to the cell body, and then along the axon to its end. At the end of the axon, the electrical impulse sets off the release of some chemicals. These chemicals cross the gap, or synapse, and start a similar electrical impulse in a dendrite of the next neuron. This is a general scheme of how nervous impulses travel in the body. A similar synapse finally allows delivery of such impulses from neurons to other cells, such as muscles cells or gland. Nervous system: Brain gets input from sensors ( receptors) & gives command to muscles. If for some emergency condition like heat, signal goes directl...