Neuron (noun, “NUR-on”)
This is one of the main cell types of the nervous system — your brain, spinal cord and nerves. It’s also frequently called a nerve cell. Neurons help the body detect and respond to information. They do this by transmitting signals from one place in the body to another.
Every time you touch something, that touch starts an electrical signal in the very tip of a neuron near your skin. This neuron then carries the information to other neurons in the brain for processing. When you want to move, for instance, the brain sends electrical signals down neurons to contract the muscles in your arm or leg. There are around 86 billion neurons in the brain and another billion in the spinal cord.
The parts of a neuron are specialized to produce, receive and move electrical signals. Usually, a neuron receives signals on small branches called dendrites. These dendrites stick out from the main body of the cell. Electrical signals go down a long tail called an axon. At the end of the axon is another set of small branches, called the axon terminal.
Electrical signals move along the axon as waves of positively and negatively charged ions. These weave in and out of the cell’s axon, rippling to the terminal. There, the neuron passes the message to another cell using chemical signals.
Because neurons transmit signals from one body part to another, they can get very long. In fact, a single neuron from the base of the spinal cord to the big toe can be more than one meter (three feet) long.
In a sentence
In a count of neurons in the outer layers of the brain, dogs beat cats — and bears, too.