Sensory, motor and relay neurones

Sensory neurones carry information from sensory receptors which detect external and internal changes to the brain and spinal cord.
They have long dendrites, these carry nerve impulses from sensory receptors towards the cell body.
The long axons carry nerve impulses from the cell body to the central nervous system.
The cell body is located halfway along the neurone, and it is directly connected to dendrites and an axon.

Motor neurones transport impulses from the central nervous system out to effectors (glands and muscles) in the body.
They have many short dendrites that carry nerve impulses from the CNS to the cell body.
The axon is a long extension that carries these impulses onward from the cell body to the effector.
The cell body is located at one end of the neuron, and it’s directly connected to numerous dendrites and a single, long axon.

Relay neurones, also known as interneurons, are the connectors or trainers between sensory and motor neurones.
They are found within the brain and spinal cord and make up the vast majority of neurones in the body.
Relay neurones have short dendrites and short axons.
Their cellular structure means they can connect to many different neurones at once, allowing them to facilitate complex reflexes and behaviours.

All nerve cells are adapted for their function of transmitting messages quickly across long distances by the long thread-like structure called the axon and thin branching strands known as dendrites.
Nerve impulses exist due to electrical differences across the cell surface membrane, known as the resting potential.
The process of transmitting impulses along a neurone is called action potential.
Synapse is the gap between neighbouring neurones where signals are transmitted from one to the other using chemicals.