Neurons space cells that have been adjusted to lug nerve impulses. A typical neuron has a cell body include a nucleus, one or much more branching filaments dubbed dendrites which command nerve impulses in the direction of the cell body and one long fibre, one axon, that carries the impulses away from it. Numerous axons have a sheath of fat material dubbed myelin bordering them. This speeds up the price at i m sorry the nerve impulses travel along the nerve (see diagram 14.1).

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Diagram 14.1 - A motor neuron

The cell human body of neurons is usually situated in the brain or spinal cord while the axon extend the whole distance come the body organ that the supplies. The neuron transferring impulses indigenous the spinal cord come the hind leg or tail of a horse, for example, can be numerous feet long. A nerve is a bundle that axons.

A sensory neuron is a nerve cell that transmits impulses native a sense receptor such together those in the eye or ear to the mind or spinal cord. A motor neuron is a nerve cell that transmits impulses native the brain or spinal cord come a muscle or gland. A relay neuron connect sensory and also motor neurons and is uncovered in the mind or spinal cord (see diagrams 14.1 and 14.2).


Diagram 14.2 - The relationship between sensory, relay and also motor neurons

Connections in between Neurons

The connection between surrounding neurons is dubbed a synapse. The two nerve cells execute not actually touch here for over there is a microscopic space between them. The electric impulse in the neurone before the synapse stimulates the manufacturing of chemicals referred to as neurotransmitters (such together acetylcholine), which space secreted into the gap.

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The neurotransmitter chemicals diffuse across the gap and when they contact the membrane that the following nerve cell they stimulate a new nervous advertise (see chart 14.3). After the impulse has passed the chemical is destroyed and also the synapse is ready to obtain the next nerve impulse.


Diagram 14.3 - A nerve and also magnification the a synapse

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