19 May

The basic unit in the nervous system is the neurone.The neuron is made up of different parts. They are sort of like regular cells because they have a nucleas, cytoplasm, and have a membrane. Yet they are different because they have special part (fibers) called dendrites and axon. Dendrites are fibers all over the cell body leading in different ways. There are many dendrites. Dendrites are the part of a neuron that take nerve impulses in. The axon is also leaving the cell body.  It goes until the synaptic buttons. There are not any branches off from the axon unless it is at the end. The axon is surrounded by a protective layer called the myelin sheath. The axon carries nerve pulses away. At the end of the axon are the synaptic buttons. The synaptic buttons connect to other neurons.Neurones come in many sizes and can be devided into three basic types, namely sensory neurone, motor neurone and relay neurone.

Sensory neurones are connected to receptors or sensory organs. They transmitted impulses from the sensory organs to the central nervous system. sensory neurons have dendrites on both ends, connected by a long axon with a cell body in the middle.

P62 sensory neuron

 Motor neurons that control muscle contractions have a cell body on one end, a long axon in the middle and dendrites on the other end;


Relay neurones are located in the central nervous system. They connect sensory neurones to motor neurones and transmit impulses between these two neurones.


The similarities between the three types of neurones are
(a) they all have a cell body
(b) they all have dendrons and dendrites
(c) they all can recieve and send out impulses


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