Three kinds of neuron
Neurons are classified by the function they carry out. There are three kinds, and together they make the chain from the last page.
Figure to be added
Sensory neurons
Carry impulses from the sense organs to the central nervous system.
Inter neurons
Lie entirely within the central nervous system and connect the other two.
Motor neurons
Carry impulses from the central nervous system to the effectors.
The three in order
Sensory in, inter across, motor out. That is the chain from the previous page, with a name for each link.
Beyond the syllabus — the three described
Sensory neuron. Nerve fibres lie on both sides of the cell body. The cell body is often situated within a ganglion — a structure formed by the cell bodies of nerve cells collected together. Its dendrites lie within a sense organ and its axon lies within the central nervous system.
Inter neuron. These neurons lie entirely within the central nervous system. Their axons are short and there are a great many dendrites. They maintain the connection between the sensory neurons and the motor neurons.
Motor neuron. A star-shaped cell body with many processes leaving it. One process is the axon, which is often very long — sometimes more than a metre. The other processes are the dendrites. The dendrites and the cell body lie within the central nervous system, and the axon endings lie within the effector.
In, across, out
Sensory neurons carry impulses from the sense organs to the central nervous system, inter neurons connect within it, and motor neurons carry impulses out to the effectors. Neurons are classified by the function they carry out.