No matter how behind you are on your to-do list, you should still be proud: You're getting a lot more accomplished right now than you're probably giving yourself credit for. In fact, you're directing, supervising and improvising many complicated functions, and you're making split-second decisions about all of them simultaneously. On top of that, you're not giving any of it one second's conscious thought.

The nervous system is a giant network of signal-transmitting neurons and the connections between them. Most of your neurons -- 100 billion or so -- are in your brain (the runner-up, your spine, has 1 billion). There's not just one type of neuron, but thousands, each with a special shape, function or purpose.

The nervous system has two parts, which both ultimately serve to distribute signals among neurons throughout the body:

• The central nervous system consists of the brain and spinal cord and acts as the primary interstate along which messages go to and from the brain.
• The peripheral nervous system serves as the highways, streets and alleyways of this transportation system. It connects the central nervous system network to the rest of the body. The peripheral nervous system has two parts: somatic (which sends messages back to the central nervous system) and autonomic (which spurs or calms the actions of your organs).

We're going to look at 10 things your nervous system handles automatically, but first, you'll have to make a conscious effort to check out the next page.