Reflex arcs are evolved in animals for quick and efficient responses. Which one of the following sequences correctly represents a reflex arc?

A reflex arc is a neural pathway that facilitates rapid, involuntary responses to stimuli. The sequence begins with a receptor detecting a stimulus, which then triggers an electrical impulse in a sensory (afferent) neuron [1]. This impulse travels to the spinal cord, where it is typically passed to a relay neuron (interneuron) [2]. The relay neuron acts as an integration center, connecting the sensory input directly to a motor (efferent) neuron within the spinal cord. The motor neuron then carries the command to an effector, such as a muscle or gland, to produce a response [1]. While the reflex arc functions independently of the brain to ensure speed, the sensory information is simultaneously sent to the brain for processing and awareness [1]. Therefore, the correct sequence is Receptor—Sensory neuron—Relay neuron in spinal cord—Brain (for information)—Motor neuron—Effector.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 6: Control and Coordination > 6.1.1 What happens in Reflex Actions? > p. 102
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 6: Control and Coordination > 6.1.2 Human Brain > p. 103