Brain: The brain is the control center of the nervous system. It processes information received from sensory organs, initiates responses, and is responsible for higher cognitive functions, emotions, and memory.

Spinal Cord: The spinal cord is a long, thin, tubular bundle of nerves that extends from the brain. It serves as a pathway for signals traveling between the brain and the rest of the body. It also plays a role in reflexes, which are rapid, involuntary responses to stimuli.

Sensory (Afferent) Division: This division carries sensory information from sensory organs (such as eyes, ears, skin) to the CNS. It allows the body to detect and respond to changes in the environment.

Motor (Efferent) Division: This division carries signals from the CNS to muscles and glands. It controls voluntary movements (somatic nervous system) and involuntary activities like heart rate and digestion (autonomic nervous system).

Controls voluntary muscle movements.

Receives sensory information from the external environment.

Allows conscious control over skeletal muscles.

Regulates involuntary bodily functions, such as heart rate, digestion, and respiratory rate.

Divided into the sympathetic and parasympathetic divisions.

Sympathetic Division: Activates the "fight or flight" response, preparing the body for stressful situations.

Parasympathetic Division: Promotes the "rest and digest" response, conserving energy and promoting relaxation.

Neurons: Specialized cells that transmit electrical and chemical signals.

Glial Cells: Support cells that provide structural and metabolic support to neurons. They include astrocytes, oligodendrocytes, microglia, and Schwann cells.

Nerves: Bundles of axons (nerve fibers) that transmit signals between the CNS and various parts of the body.

Synapses: Junctions where neurons communicate with each other or with target cells.