The nervous system is a complex structure of nerves of neurons that transmit signals around the body to coordinate actions. It is in effect our body's electrical wiring.
The nervous system of vertebrates (which includes humans and animals that have backbones and spinal columns) has two parts, the central nervous system (CNS) and the peripheral nervous system (PNS).
The CNS includes the brain, spinal cord and retina of the eyes. The brain is protected by the skull, and the spinal cord by the skeletal vertebrae.
The PNS includes all other nervous system structures that sit outside the CNS but that help connect the CNS to areas of the body.
Nerves are enclosed bundles of long fibers called axons which are made up of nerve cells. There are two types of nerve cells: neurons and glial cells.
Glial (or glia) cells are derived from the Greek word "glue". They are specialized cells that provide structure and support to neurons. They help hold neurons in place, supply nutrients to neurons, destroy germs, remove dead neurons, and direct axons of neurons.
Some types of glial cells generate a substance called myelin that coat axons and work as electrical insulation to help them quickly and efficiently transmit signals.
Neurons quickly and precisely send signals as electrochemical waves along axons to other cells. There are two types of neurons, sensory neurons and motor neurons.
Sensory neurons change light, touch and sound into neural signals which are sent back to our CNS to help our body understand and react to its surroundings.
Motor neurons transmit neural signals to activate muscles or glands.
There are approximately 100 billion neurons in the human brain and 13.5 million neurons in the human spinal chord.
The nervous system can transmit signals at speeds of 100 meters (328 feet) per second.
The field of science that focuses on the study of the nervous system is called neuroscience. Neurology is the medical branch of study and treatment, while doctors and surgeons in this field are called neurologists and neurosurgeons.
Nerves in our body can be vulnerable to both physical damage and damage through diseases. Damage to nerves can cause great pain, loss of feeling, or loss of muscle control.
Physiatrists help rehabilitate patients with nervous system damage.