Cells called neurons connect with one another to send and receive messages in the brain and spinal cord. Many neurons working together are responsible for every decision made, every emotion or sensation felt, and every action taken.
The complexity of the central nervous system is amazing. There are approximately 100 billion neurons in the brain and spinal cord combined. As many as 10,000 different subtypes of neurons have been identified, each specialized to send and receive certain types of information.
Each neuron is made up of a cell body, which houses the nucleus. Axons and dendrites form extensions from the cell body.