neuron

Your brain is made up of cells. Specialized cells called neurons allow you to think, feel, and move. Neurons aren't only found in the brain. These tiny excitable cells form a network throughout your body. They send messages from your body to your brain, all around your brain, and from your brain out to the muscles. Neurons connect through long, spidery branches, carrying signals that control all your thoughts and behaviors.

Definition: nerve cells that carry signals between the brain and body
Parts: dendrites, cell body, axon
Cool Fact: In the human body, the longest neuron stretches from the spinal cord all the way to the toes. It can be more than three feet (one meter) long!
Cool Fact: The longest neuron in the animal kingdom goes all the way down the giraffe's neck.

Image credits: main image, © Richard Tibbitts/Antbits.