Anatomy 201: Nervous System

Nervous System

The organ system consisting of the brain, spinal cord, and nerves that coordinates body activities by transmitting electrical and chemical signals.

Central Nervous System (CNS)

The division of the nervous system consisting of the brain and spinal cord, which integrates and processes sensory information and coordinates responses.

Peripheral Nervous System (PNS)

The division of the nervous system consisting of all nerves outside the brain and spinal cord that connect the CNS to the rest of the body.

Neuron

A specialized cell that transmits electrical impulses (nerve signals) throughout the nervous system, consisting of a cell body, dendrites, and an axon.

Dendrite

A branched extension of a neuron that receives electrical signals from other neurons and transmits them toward the cell body.

Axon

A long, slender projection of a neuron that conducts electrical impulses (action potentials) away from the cell body toward other cells.

Synapse

The junction between two neurons or between a neuron and a target cell, where neurotransmitters are released to transmit signals across the synaptic cleft.

Neurotransmitter

A chemical messenger released at a synapse that transmits signals between neurons or from neurons to target cells (e.g., dopamine, serotonin, acetylcholine).

Action Potential

A rapid, temporary reversal of the electrical charge across a neuron's membrane that propagates along the axon as a nerve impulse.

Myelin Sheath

An insulating fatty layer surrounding the axons of many neurons that increases the speed of electrical signal transmission.