A receptor of the second order, also known as a secondary receptor, refers to a specialized sensory cell or structure that receives information from primary receptors and relays it to the brain or central nervous system (CNS) for further processing. These receptors play a crucial role in transmitting sensory information from the body to the brain, allowing us to perceive and respond to various stimuli.
Unlike primary receptors, which are directly stimulated by environmental cues such as light, sound, pressure, or temperature, receptors of the second order are situated in sensory organs or neural pathways and receive input from the primary receptors. They enhance or modify the signals received, facilitating interpretation and integration of sensory information.
These secondary receptors are found in different parts of the body, depending on the sense they are associated with. For example, in the visual system, secondary receptors in the retina receive signals from photoreceptor cells (rods and cones) and pass them on to the optic nerve for transmission to the brain.
Similarly, in the auditory system, hair cells located in the cochlea of the inner ear act as secondary receptors, converting sound waves received by the outer and middle ear into electrical signals that can be processed by the brain.
In summary, receptors of the second order are intermediary structures or cells that receive signals from primary receptors and help facilitate the transmission of sensory information to the brain or CNS.
