Can you explain what the stages of a reflex action are; for example what actually happens when you touch a hot object?

Firstly, the whole point of a reflex is to create a QUICK reaction to a STIMULUS. So, the first stage of a reflex is SENSATION - i.e when you first touch the hot object the receptors in the skin will sense this and be stimulated. This stimulation causes an electrical impulse to pass along the SENSORY NEURONES until it reaches the RELAY neurones (which are located in the the central nervous system - CNS). The area between the sensory neurone and relay neurone is a SYNAPSE. At the synapse a chemical diffuses from the sensory neurone to the relay neurone which stimulates another electrical impulse along the relay neurone. Once this impulse reaches the end of the relay neurone, another chemical is released from here to the MOTOR neurone. A new electrical impulse travels along the motor neurone to the EFFECTOR which in this case will be the muscles of the arm (biceps). Once the impulse gets to this point, the effector is stimulated to RESPOND i.e. the muscles will contract which means the hand and arm move rapidly away from the HOT object; and this is the REFLEX PATHWAY. (I am happy to draw a diagram for a more visual description of this).