Imagine that you could miniaturize yourself, not actually but metaphorically in your mind’s eye, of course. If you could really do this, shrink yourself to the size of a single cell and then somehow stand back and study the environment around you, what you would see as yourself would not be a single entity but a bustling community of more than 50 trillion individual cells. Most of the cell’s structures are referred to as organelles, which are its ‘miniature organs,’ suspended within a jelly-like cytoplasm. These organelles are miniature versions of tissues and organs of your own body. Each nucleus-containing cell (eukaryote) possesses the functional equivalent of your nervous system, digestive, respiratory, excretory, endocrine, skeletal, circulatory, skin, and immune systems. Groups of specialized cells that form the tissues and organs of the nervous system, are concerned with reading and responding to environmental stimuli. The nervous system’s job is to perceive the environment around it (both inside and outside the body) and coordinate the behavior of all the cells in your vast cellular community.