Neuronii

Neuronii, or neurons, are the fundamental signaling units of the nervous system. They process and transmit information through electrical and chemical signals and form the circuits that underlie sensation, movement, thought, and behavior. In Romanian usage, “neuronii” is the plural form of neuron.

An individual neuron typically consists of a cell body (soma), dendrites that receive signals, and a long axon that transmits signals to other cells. The cell body contains the nucleus and organelles necessary for metabolism. Dendrites provide a large receptive surface area, while axons may be insulated by a myelin sheath produced by oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system. Gaps in the myelin, called nodes of Ranvier, enable saltatory conduction, speeding up signal transmission.

Communication occurs at synapses, where the axon terminal releases neurotransmitters into the synaptic cleft in response to an action potential. These chemicals bind receptors on the next cell, potentially triggering a new electrical signal. Neuronal activity is shaped by ion channels, receptor types, and neuromodulators, allowing a range of excitation and inhibition that underpins complex signaling networks.

Neurons are diverse in form and function. They can be classified by function as sensory (afferent), motor (efferent), or interneurons, and by morphology as multipolar, bipolar, or unipolar. They exhibit plasticity, adjusting synaptic strength with experience, which supports learning and memory. Neurogenesis in adults is limited and region-specific.

Disruptions to neuronal function are central to many disorders, including neurodegenerative diseases such as Alzheimer's and Parkinson's, as well as injuries that damage axons. Understanding neuron structure and signaling remains a core focus of neuroscience.