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are chains of chemicals arranged like rungs on a twisted ladder.

Shaped like a small, wrinkled melon, weighs about 1,350 grams (less than 3 pounds), has a pinkish-white color, and has the consistency of firm jelly

is fueled by sugar (glucose) and has about 1 trillion cells that can be divided into two groups—glial cells and neurons.

have a structural role within the CNS and also regulate nerve firing rates, brain plasticity (guiding early brain development), and immune responses

insulate, protect, and help neurons to develop and migrate

have phagocytic properties, digesting foreign particles

• - is a brain cell with two specialized extensions. One extension is for receiving electrical signals, and a second, longer extension is for transmitting electrical signals

• - form a vast, miniaturized informational network that allows us to receive sensory information, control muscle movement, regulate digestion, secrete hormones, and engage in complex mental processes such as thinking, imagining, dreaming, and remembering

is a relatively large, egg-shaped structure that provides fuel, manufactures chemicals, and maintains the entire neuron in working order.

are branchlike extensions that arise from the cell body; they receive signals from other neurons, muscles, or sense organs and pass these signals to the cell body.

is a single threadlike structure that extends from, and carries signals away from, the cell body to neighboring neurons, organs, or muscles