Voluntary actions involve conscious thought (thinking time).
Reflex actions do not involve conscious thought (thinking time) and happen very quickly to avoid unnecessary damage to the body.
One example of this is rapidly removing your hand from a hot plate before it gets burned.
Reflex arc
A reflex action happens quickly because the reflex pathway is kept short and involves the smallest number of neurones and synapses possible.
There are 3 neurones and 2 synapses involved in a reflex arc.
The sensory neurone - carries information from the receptor to the spinal cordThe part of central nervous system of a mammal which runs inside its backbone (coordinator).
The association neurone - joins the sensory neuroneThe nerve cell that transmits electrical impulses from receptors in the sense organs to the CNS. and motor neuroneThe nerve cell that carries electrical impulses from the CNS to effectors such as muscles or glands..
The motor neurone - carries information from the spinal cord to an effectorThe organ, tissue or cell that produces a response. that can cause a response.
The association and motor neurones both begin with the cell body.