Every murderer knows they face life behind bars if they are caught and convicted. But only in a few rare cases does that really mean they will never taste freedom again â there are fewer than 50 people who have been told they will die in jail.
The human body is made up of trillions of cells. Cells of the nervous system, called nerve cells or neurons, are specialized to carry messages through an electrochemical process. The human brain has approximately 100 billion neurons.
The nervous system consists of two main parts: the central nervous system and the peripheral nervous system: 1  The central nervous system is made up of the brain and spinal cord.he brain sends messages through the spinal cord and nerves of the peripheral nervous system to control the movement of the muscles and the function of internal organs. The basic working unit of the nervous system is a cell called a neuron. The human brain contains about 100 billion neurons.