Your nervous system is your body's information network. The brain and spinal cord do the processing and decision-making, the nerves branching out from them carry the signals to and from every muscle, organ, and patch of skin. The brain runs on the same building block as every nerve in your toes: the neuron, a specialised cell whose entire job is transmitting information.

Neurons

A neuron is a specific type of cell that the brain and nervous system are made of for transmitting information.

A neuron has three main parts:

• Cell body (soma): contains the nucleus, DNA, and the cell's machinery (same as any other cell)
• Dendrites: branch-like extensions that receive incoming signals from other neurons
• Axon: a long projection that sends signals out to other neurons or muscles. Some axons are very short, others can be over a metre long running from your spinal cord to your foot

Neurons talk to each other through a combination of electrical and chemical signals.

1. An electrical signal travels down the axon
2. At the end of the axon it triggers the release of **neurotransmitters (**chemical messengers) into a tiny gap called the synapse
3. The neurotransmitters cross the synapse and bind to receptors on the next neuron's dendrites
4. This triggers a new electrical signal in that neuron

This is happening billions of times per second throughout your brain and nervous system.

You're born with roughly 86 billion neurons and for the most part you keep them for life. Neurons don't replace themselves, keeping them alive and healthy is entirely dependent on survival signals, which is what neurotrophins provide.

They form incredibly specific networks and connections & they are energy hungry, the brain uses about 20% of your total energy.

For a long time scientists believed zero new neurons were ever produced after birth. This turned out to be partially wrong. The hippocampus (the memory region) continues producing new neurons throughout life in a process called neurogenesis.

Neurotransmitters