These supporting nerve cells are located between and around your neurons to insulate, protect and nourish them. Over half of all the nerve cells in your nervous system do not transmit any impulses. It diffuses from this neuron across a junction and excites the next neuron. So when a nerve impulse reaches the end of one neuron, a neurotransmitter chemical is released. Stimuli such as light, sound or pressure all excite your neurons, but in most cases, chemicals released by other neurons will trigger a nerve impulse.Īlthough you have millions of neurons that are densely packed within your nervous system, they never actually touch. To create a nerve impulse, your neurons have to be excited. Your neurons carry messages in the form of electrical signals called nerve impulses. Association neurons, which connect your sensory and motor neurons.Motor neurons, which pass instructions from your central nervous system to other parts of your body, such as muscles or glands.Sensory neurons, which pass information about stimuli such as light, heat or chemicals from both inside and outside your body to your central nervous system.Your neurons can be divided into three types: Nerves are tight bundles of nerve fibres. There are two different kinds of nerve fibres: fibres that carry information towards the cell body, called dendrites, and fibres that carry information away from it, called axons. These fibres vary in length from microscopic to over 1 metre. Neurons are highly specialised to transmit messages from one part of your body to another.Īll neurons have a cell body and one or more fibres. Your nervous system contains millions of nerve cells, called neurons. Neurotransmitters: Chemicals released by one neuron to excite a neighbouring one Nerve impulses: Electrical signals carrying messages Neurons: Messenger cells in your nervous system A new counting method, the isotropic fractionator, has challenged the notion that glia outnumber neurons and revived a question that was widely thought to have been resolved. Function: To transmit messages from one part of your body to another For half a century, the human brain was believed to contain about 100 billion neurons and one trillion glial cells, with a glia:neuron ratio of 10:1.

Brain cells consist of neurons and