In a reflex arc, which component directly detects a stimulus?

In a reflex arc, which component directly detects a stimulus?

• A. Receptor
• B. Interneuron
• C. Motor Neuron
• D. Effector

Answer: (A)

The receptor. Receptors are specialized sensory structures that directly detect a stimulus (such as touch, temperature, or stretch) and convert it into a nerve impulse. This impulse then travels through a sensory neuron toward the spinal cord or brainstem, where it may be processed by interneurons before a motor neuron carries a response to an effector, like a muscle. The other components—interneuron, motor neuron, and effector—participate in the reflex response, but they do not directly sense the stimulus themselves.

The receptor. Receptors are specialized sensory structures that directly detect a stimulus (such as touch, temperature, or stretch) and convert it into a nerve impulse. This impulse then travels through a sensory neuron toward the spinal cord or brainstem, where it may be processed by interneurons before a motor neuron carries a response to an effector, like a muscle. The other components—interneuron, motor neuron, and effector—participate in the reflex response, but they do not directly sense the stimulus themselves.