The end result is the simplest form of etching. There are more complicated ways to create more intricate etchings by using a number of different plates and colors. There is also a process to add different tones to the image that involves adding resin dust to the plate and heating it.
Nerves carry electrochemical signals to and from different areas of the nervous system as well as between the nervous system and other tissues and organs. Nerves are divided into four classes: Cranial nerves connect your sense organs (eyes, ears, nose, mouth) to your brain.
The brain sends messages through the spinal cord and nerves of the peripheral nervous system to control the movement of the muscles and the function of internal organs. The basic working unit of the nervous system is a cell called a neuron. The human brain contains about 100 billion neurons.