Question

The sequence of a reflex arc is

• A. Receptor $\to$ Sensory neuron $\to$ Motor neuron $\to$ Effector $\to$ Response
• B. Effector $\to$ Sensory neuron $\to$ Motor neuron $\to$ Receptor $\to$ Response
• C. Effector $\to$ Motor Neuron $\to$ Interneuron $\to$ Receptor $\to$ Response
• D. Receptor $\to$ Motor neuron $\to$ Sensory neuron $\to$ Effector $\to$ Response

Answer 1

The correct option is A Receptor $\to$ Sensory neuron $\to$ Motor neuron $\to$ Effector $\to$ Response

Reflex arc transmits the sensory information from receptor to effector via spinal cord. It consists of sensory receptor, afferent (sensory) neuron, centre, efferent (motor) neuron and effector organ. The afferent/sensory neurons transmit the sensory information from sensory receptors to spinal cord (sensory pathway). Detection of environmental stimulus by receptors forms the first step of reflex arc.

Sensory neurons receive the information from receptors while motor neurons transmit the nerve impulses from CNS to effectors (muscles and glands).

The interneurons of spinal cord integrate the incoming information and signal is relayed to motor/efferent neurons. The motor pathway transmits the signal from motor neurons to the effector organs (muscles and glands etc). The effector organs respond according to the information carried by motor pathway.

Therefore, the correct answer is option A.