nervoussystem

The nervous system (often written as nervoussystem) is the body's primary control and communication network. It coordinates sensation, movement, and cognition, and regulates many body functions. It comprises the central nervous system, which includes the brain and spinal cord, and the peripheral nervous system, consisting of the nerves and ganglia outside the brain and spinal cord.

At the cellular level, the nervous system is built from neurons, which transmit electrical and chemical signals, and glial cells, which provide support and maintenance. Neurons communicate across synapses using neurotransmitters such as glutamate, GABA, acetylcholine, dopamine, and serotonin.

The CNS integrates information and generates responses; the PNS relays sensory input to the CNS and carries motor commands from the CNS to muscles and glands.

Subdivisions of the PNS include the somatic nervous system, which controls voluntary movements, and the autonomic nervous system, which regulates involuntary functions. The autonomic system comprises the sympathetic and parasympathetic branches, and, in parts of the gut, the enteric nervous system.

Protection and development: The nervous system develops from the embryonic neural tube. It is protected by the meninges, cerebrospinal fluid, and the blood-brain barrier, which regulate the neuronal environment.

In everyday function, the nervous system supports perception, learning, memory, and behavior through plasticity and adaptation. While some repair is possible, especially in the peripheral nervous system, CNS recovery after injury is often limited.

Disorders of the nervous system include epilepsy, multiple sclerosis, Parkinson's disease, Alzheimer's disease, neuropathies, and spinal cord injuries.