noun, plural: reflex arcs
A neural pathway that controls reflex reactions
In physiology, a reflex reaction refers to an involuntary response or a reaction to a stimulus. The response is innate and need not to be learned or thought about. It is an involuntary reaction of the body to a stimulus. The reflex arc is a neural pathway that mediates or controls the reflex reaction of the body. In particular, the receptors route sensory signals to the spinal motor neurons, which in turn activate the effector cells to carry out a reflex action. The reaction of the body would therefore be quick. The body responds to a stimulus even before the impulse reaches the brain allowing a faster response to a stimulus.
The reflex arcs may be classified to as autonomic or somatic. An autonomic reflex arc is one that affects the inner organs whereas a somatic reflex arc affects muscles. Another way to classify reflex arcs is to base it on the number of chemical synapse involved in a reflex action. A neural pathway that involves one synapse, i.e. from a sensory neuron to a motor neuron, is described as monosynaptic as opposed to the polysynaptic that involves more than one synapse.