now on this structure, when it comes to tracing activity, this system, like other natural & man-made systems, uses energy to do its work …
so where does the NS … get its energy?
well, we’ve just seen that the sensory groups in the body’s tissue … the sensory receptors in the eyes, ears, skin & muscle, for example … are the neuron groups that begin the conscious pathways …
here, embedded in the tissues … they are exposed to many forms of energy in the body & environment … energy such as
light & sound waves … tension, temperature & pressure, which are forms of energy … they’re designed to absorb
and as these sensory groups absorb energy … a pattern of the sensory group’s neurons … is energized … and, besides
updating the current character of the sensory group … the energized neurons in this pattern … instantly translate the energy they’ve absorbed … into another form of energy … electro-chemical energy … which we call impulses
and this pattern of impulses … is then immediately generated to the next group in the circuitry … & the next & the next
and so on … forming a flashing … lightening-like series of energized neuron groups … called an impulse trail
we can picture this as being like one of those cycling icons … you see in the middle of a TV … when an app or video is loading