Which is the correct sequence of the components of a reflex arc?
(a) Receptors Muscles Sensory neuron Motor neuron Spinal cord
(b) Receptors Motor neuron Spinal cord Sensory neuron Muscle
(c) Receptors Spinal cord Sensory neuron Motor neuron Muscle
(d) Receptors Sensory neuron Spinal cord Motor neuron Muscle
Answer: D
Solution: The reflex arc is a neural pathway that controls a reflex. Reflex arc is a part of the PNS and is responsible for actions performed in response to certain stimuli, such as pulling a hand away from a hot object. Its consists of 5 components- a receptor that receives the initial stimulus, such as skin, muscles or organs, a sensory neuron that carries the signal to the central nervous system (the spinal cord), an interneuron that relays the information to the central nervous system, and one or more motor neurons that relay the information to the final component of the arc, the effector. The effector could be a muscle, a gland or both.