The nervous system is a complex, highly coordinated network of tissues that communicate via electro chemical signals. It is responsible for receiving and processing information in the body and is divided into two main branches: the central nervous system and the peripheral nervous system.
The central nervous system receives and processes information from the senses. The brain and the spinal cord make up the central nervous system. Both organs lie in a fluid called the cerebrospinal fluid, which cushions and nourishes the brain. The blood-brain barrier protects the cerebrospinal fluid by blocking many drugs and toxins. This barrier is a membrane that lets some substances from the blood into the brain but keeps out others.
The spinal cord connects the brain to the rest of the body. It runs from the brain down to the small of the back and is responsible for spinal reflexes, which are automatic behaviors that require no input from the brain. The spinal cord also sends messages from the brain to the other parts of the body and from those parts back to the brain.
The brain is the main organ in the nervous system. It integrates information from the senses and coordinates the body’s activities. It allows people to remember their childhoods, plan the future, create term papers and works of art, talk to friends, and have bizarre dreams. Different parts of the brain do different things.