What are the differences between photo receptors and signal receptors?

Photoreceptors are specialized sensory cells that detect light and convert it into electrical signals, primarily found in the retina of the eye. In contrast, signal receptors are a broader category that includes various types of receptors that detect chemical signals, such as hormones or neurotransmitters, and initiate a cellular response. While both types of receptors are essential for communication within organisms, photoreceptors are specifically tuned for light detection, whereas signal receptors can respond to a wide range of stimuli. Their mechanisms of action and the types of signals they respond to differ significantly.