define nervous system

The nervous system is a complex network of cells, tissues, and organs that coordinates and regulates the functions of the body. It is responsible for receiving sensory information from the environment, transmitting signals between different parts of the body, and controlling various bodily processes. The nervous system is divided into two main components: the central nervous system (CNS) and the peripheral nervous system (PNS). 1. Central Nervous System (CNS): The CNS consists of the brain and the spinal cord. It serves as the main control center of the body, processing and integrating sensory information, initiating motor responses, and regulating higher cognitive functions. The brain is responsible for tasks such as consciousness, thinking, memory, and emotions, while the spinal cord facilitates communication between the brain and the rest of the body and controls certain reflex actions. 2. Peripheral Nervous System (PNS): The PNS includes all the nerves and ganglia (clusters of nerve cell bodies) outside the CNS. It connects the CNS to the rest of the body. The PNS is further divided into the somatic nervous system and the autonomic nervous system. - Somatic Nervous System: This division controls voluntary movements and transmits sensory information from the sensory organs to the CNS. It enables conscious perception and motor responses to external stimuli. - Autonomic Nervous System (ANS): The ANS regulates involuntary processes that are essential for maintaining homeostasis. It controls functions such as heart rate, digestion, respiration, and glandular secretion. The ANS has two main subdivisions: the sympathetic nervous system, which prepares the body for "fight-or-flight" responses, and the parasympathetic nervous system, which promotes rest, relaxation, and "rest-and-digest" responses. The nervous system consists of specialized cells called neurons, which are responsible for transmitting electrical and chemical signals. Neurons communicate with each other through connections called synapses. Supporting cells called neuroglia or glial cells provide structural support, insulation, and nourishment for neurons. Overall, the nervous system plays a crucial role in coordinating and controlling bodily functions, allowing organisms to interact with their environment, process information, and respond accordingly.