Final answer:
Pruritus is mediated by specialized free nerve endings known as unmyelinated C-fibers in the skin, which are a type of nociceptive nerve fiber responsible for transmitting itch sensations to the central nervous system.
Step-by-step explanation:
The skin acts as a sensory organ because it contains specialized sensory nerve structures that detect various stimuli, including touch, surface temperature, and pain. Among these structures, certain types of nerve fibers are responsible for mediating pruritus, commonly known as itching.
In addition to mechanoreceptors like the Meissner corpuscle and the Pacinian corpuscle that detect touch and vibration, there are also free nerve endings that are responsible for sensing pain and temperature. These free nerve endings are also sensitive to chemicals released in response to an allergic reaction, irritation, or other stimuli that can cause the sensation of itch.
Specifically, pruritus is mediated by unmyelinated C-fibers. These are a type of nociceptive nerve fibers that transmit itch signals from the peripheral skin to the central nervous system. The somatosensory system then processes these signals, resulting in the perception of itch.