Nervous System

Brain · spinal cord · nerves

How does the nervous System work?

A network of about 86 billion neurons in the brain plus nerves reaching every part of you, carrying electrical and chemical signals.

How it works

Neurons send electrical impulses along their length and chemical messengers (neurotransmitters) across the gaps between them.

Two divisions

The central nervous system (brain and spinal cord) processes; the peripheral nervous system carries signals to and from the body.

Nutrients involved

Sodium and potassium create nerve impulses; vitamin B12 helps maintain myelin; vitamin B6 helps make neurotransmitters; iodine is needed for brain development.

Evidence & sources

• The human brain contains roughly 86 billion neurons. Evidence: strong. Known: Estimated by counting cell nuclei in dissolved brain tissue (isotropic fractionator). Unknown: Counts vary between individuals; the method has its own margin of error. Source: Azevedo et al., Journal of Comparative Neurology, Equal numbers of neuronal and nonneuronal cells make the human brain an isometrically scaled-up primate brain (2009).

Connected topics

• Potassium
• Sodium
• Vitamin B12
• Vitamin B6
• Iodine
• Sleep & Recovery

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General education only, not medical advice. Drafted Oct 2026 · pending qualified expert review.