Neuron
A neuron is a specialized nerve cell that receives, processes, and sends information through the nervous system. Neurons use electrical signals within the cell and chemical or electrical signaling at synapses to coordinate sensation, movement, thought, memory, emotion, and body regulation.
What a neuron is
A neuron is a nerve cell built for communication. It can collect signals from other cells, combine those inputs, and send an output to other neurons, muscles, or glands. Neurons are not the only cells in the nervous system, but they are the main signaling units that make circuits possible.
Parts of a neuron
Most neurons have a cell body, dendrites, an axon, and axon terminals. The cell body contains the nucleus and much of the machinery that keeps the cell alive. Dendrites usually receive incoming signals. The axon carries outgoing signals away from the cell body, sometimes across long distances. Axon terminals communicate with target cells.
Electrical signaling
Neurons maintain electrical differences across their membranes. When incoming signals push a neuron past a threshold, it can produce an action potential: a brief electrical pulse that travels along the axon. This pulse is not a thought by itself; it is one unit of signaling that circuits use in patterns, timing, and networks.
Synapses and neurotransmitters
A synapse is a connection point where one neuron influences another cell. In many synapses, an action potential reaches an axon terminal and triggers release of neurotransmitters into a tiny gap. Those chemicals bind receptors on the next cell and can make that cell more or less likely to fire. Some synapses transmit electrically through direct current flow.
Dendrites as input trees
Dendrites are often branched, giving a neuron many places to receive input. Their shape matters because inputs arriving on different branches can be weighted, combined, amplified, or dampened. A neuron is not simply a wire; its structure helps determine how it interprets signals from many other cells.
Axons, myelin, and speed
Axons can be short or very long. Many axons are wrapped in myelin, an insulating layer made by support cells. Myelin helps signals travel faster and more efficiently by letting action potentials jump between exposed gaps called nodes. Damage to myelin can disrupt nervous-system communication.
Types of neurons
Neurons vary widely. Sensory neurons carry information from the body and environment. Motor neurons send commands to muscles. Interneurons connect neurons within the brain and spinal cord. Other classifications describe shape, neurotransmitter type, firing pattern, location, or role in a circuit.
Growth, learning, and plasticity
Neurons form connections during development as axons grow, find targets, and refine circuits. Connections can also change with experience, injury, learning, and disease. Synapses may strengthen, weaken, appear, or disappear. This plasticity is one reason nervous systems can adapt, but it also means neural circuits are shaped by timing, activity, and context.
Neurons and disease
Neuron damage or dysfunction can affect movement, sensation, memory, mood, sleep, speech, vision, pain, and autonomic control. Neurological diseases may involve neuron death, abnormal signaling, inflammation, genetic changes, disrupted myelin, toxic protein buildup, blood-flow problems, infection, trauma, or altered synapses.
Why it matters
Neurons matter because they link biology to experience. Every movement, remembered face, reflex, sensation, sentence, fear response, and learned skill depends on networks of cells exchanging signals. Understanding neurons gives readers a foundation for neuroscience, neurology, psychology, artificial neural network metaphors, and the limits of those metaphors.