Neural Control and Coordination — BIOLOGY STD 11 Science — Question

The entire process of response to a peripheral neural stimulation, that occurs involuntarily, i.e., without conscious effort or thought and requires the involvment of a part of the central neural system is called a reflex action.
The reflex pathway comprises at least one afferent neuron (receptor) and one efferent effector or excitor neuron appropriately arranged in a series. The afferent neuron receives signal from a sensory organ and transmits the impulse via a dorsal nerve root into the CNS (at the level of spinal cord). The efferent nueuron then carries signals from CNS to the effector. The stimulus and response thus forms a reflex arc as shown below in the knee jerk reflex.