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Biochemistry

Neurons

The main cells of the nervous system, transmitting electrical and chemical signals

A neuron with a cell body, dendrites, an axon and a synapse with a neighboring cell

Neurons are nerve cells, the main working units of the brain and the entire nervous system. The human brain has about 86 billion of them. Neurons receive, process and transmit information using electrical and chemical signals.

The structure of a neuron

A typical neuron has a cell body (soma), many short processes — dendrites, which receive signals, and one long axon that passes the signal on. Many axons are covered with myelin, which speeds up conduction. The point of contact between neurons is called a synapse.

How neurons transmit a signal

Inside a neuron the signal travels as an electrical impulse (an action potential). At the synapse it becomes chemical: neurotransmitters are released and act on the next cell. The strength of synaptic connections can change — this is the basis of neuroplasticity, learning and memory.

Neurons and aging

The old idea of massive neuron death during normal aging is greatly exaggerated. Today it is thought that in healthy aging changes in synapses, the branching of processes and the white matter matter more than a total loss of cells. Massive neuron death is characteristic of neurodegeneration. A limited formation of new neurons is possible (see neurogenesis). Neurons are supported by physical activity (through BDNF), healthy vessels and the work of mitochondria.

Calculate using this marker

Calculators where Neurons is used directly:

Cognitive Age 20 questions on memory, thinking speed, and mental flexibility — your cognitive age in 5 minutes Open Mental Age 12 questions on emotion, openness, and maturity — the age of your mind across five personality dimensions Open

Frequently asked questions

Do neurons regenerate?

Mature neurons barely divide, so there is no mass regeneration. A limited formation of new neurons is possible in the hippocampus (neurogenesis, its extent is debated), and functions are partly compensated by rewiring the connections — neuroplasticity.

How many neurons are in the human brain?

About 86 billion neurons, plus a comparable number of glial cells. Each neuron can form thousands of synaptic contacts, building vast neural networks.

Related terms

Neuroplasticity The brain's ability to rewire connections and form new ones Neurogenesis The formation of new neurons, including in the adult brain Neurodegeneration The progressive death of neurons — the basis of Alzheimer's, Parkinson's and dementias BDNF (Brain-derived neurotrophic factor) A protein that acts as "fertilizer" for neurons and synapses Neural network (AI model) An AI algorithm that mimics the working of the brain's neurons — the basis of predictive medical models Mitochondria The cell's "power plants" — their dysfunction accelerates aging Cognitive aging Age-related changes in memory, thinking speed and concentration — normal, not a disease

Sources

  1. NINDS — Brain Basics: The Life and Death of a Neuron
  2. Neuroplasticity (StatPearls, NCBI Bookshelf)
  3. Human Hippocampal Neurogenesis Persists throughout Aging (PMC)
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This content is educational and does not replace consultation with a physician. Reference ranges may vary depending on the laboratory and method — rely on the ranges stated on your own test report.
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