This is part two of a three-part series. Find part one and part three here.

Amazing Brain Facts

Your brain weighs about three pounds, and is the consistency of soft tofu. It is made of about 1.1 trillion cells. About a hundred billion of these cells are neurons; the others are the support structure of the brain, the white matter, the glial cells, predominantly, that help build myelination around the long axonal fibers of the neurons, which accelerate neurotransmission.

Each of those neurons, on average, has about five thousand connections with other neurons. That creates about five hundred trillion connections, called synapses. These are tiny little junctions between neuron “A” and neuron “B” where they communicate. In most neurons, each time a neuron fires, neurochemicals move across the synapse. (A small fraction of your neurons make direct, electrical connections.)

Each neuron is always either firing, or not. Each firing is a signal, like “green light/red light;” it tells the downstream neuron to fire or not.

So each neuronal firing is like a bit of information in a computer, a zero or a one. Most of the neurons in your brain are firing five to fifty times a second. They are very, very busy.

As a result, this little organ, two percent of body weight, uses twenty to twenty-five percent of the body’s metabolic supplies. Even in the deepest sleep, even in a coma, the brain is busy. It’s like a refrigerator; it’s always on. The brain keeps going so that if you’re suddenly attacked in the wild or you’ve got to deal with something in your cave, kaboom! You’re ready to go.