Neuronen

Neuronen (neurons) are specialized cells of the nervous system responsible for transmitting and processing information through electrical and chemical signals. They form the core components of brain circuits, spinal cord networks, and peripheral nerves, enabling sensation, movement, thought, and emotion.

A typical neuron consists of a cell body (soma) that contains the nucleus, dendrites that receive inputs, and a long axon that conducts electrical impulses away from the soma. The axon ends in terminals that form synapses with other neurons or effector cells. The cell membrane maintains a resting potential and uses voltage-gated ion channels to generate action potentials.

Many neurons are insulated by myelin, produced by glial cells (oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system). Myelin increases signal speed, and gaps called nodes of Ranvier allow saltatory conduction.

Neurons communicate mainly at chemical synapses, where the arrival of an action potential triggers release of neurotransmitters. These chemicals bind to receptors on the postsynaptic neuron, modulating its excitability. Neurotransmitter removal and reuptake events terminate signaling.

Neurons are diverse in form and function. Broad categories include sensory (afferent) neurons, which carry information from the periphery to the CNS; motor (efferent) neurons, which control muscles and glands; and interneurons, which connect neurons within the CNS. Plasticity allows neurons to change strength and connections in response to experience.

Neurons developed early in animal evolution and continue to adapt. The brain uses a significant portion of the body's energy, and synaptic changes underpin learning and memory. The neuron doctrine, established in the late 19th century, proposed that neurons are discrete units communicating at synapses.