nervesystem

The nervous system is the biological information network that coordinates actions and transmits signals between different parts of the body. In humans and many other animals, it comprises two main parts: the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS), which consists of nerves and ganglia outside the CNS. The CNS processes information and generates responses, while the PNS carries sensory input to the CNS and conveys motor commands to muscles and glands.

Nerve cells, or neurons, are the primary signaling units. They communicate by electrical impulses and chemical messengers at synapses. Glial cells provide support, insulation, and metabolic assistance. The nervous system uses networks of neurons to relay information rapidly, allowing perception, thought, movement, and regulation of internal conditions. The autonomic nervous system controls involuntary functions such as heart rate and digestion, while the somatic nervous system governs voluntary movement and sensory awareness.

Protection and development include the skull and vertebral column, meninges, and cerebrospinal fluid, along with the blood-brain barrier that regulates entry to the brain. The nervous system develops from the neural tube in the embryo and shows plasticity, meaning connections can change in response to experience.

Disorders of the nervous system include neurodegenerative diseases, strokes, epilepsies, and injuries, which can affect sensation, movement, cognition, or behavior. Advances in imaging, electrophysiology, and neuropharmacology continue to enhance understanding and treatment, while ethical considerations shape research and clinical practice.