Final answer:
Pruritus is mediated by afferent fibers, which are unmyelinated fibers such as C-fibers that transmit sensory information from the skin to the central nervous system, leading to the sensation of itching.
Step-by-step explanation:
Pruritus, commonly known as itching, is a sensation that prompts the desire to scratch. It involves the skin, which acts as a sensory organ with a rich innervation of various types of receptors and nerve fibers. These include mechanoreceptors, thermoreceptors, and nociceptors amongst others, all of which contribute to the sense of touch, temperature, and pain.
The specific type of nerve fibers that mediate pruritus are afferent fibers. These are sensory nerves that send impulses from the sensory cells in the skin to the central nervous system (CNS). Conversely, efferent nerves are motor nerves that transmit impulses from the CNS to muscles. Among these sensory nerves, unmyelinated fibers such as C-fibers often play a significant role in the sensation of pruritus. They are characterized by their relatively slow conduction velocity, due to the lack of a myelin sheath, and are sensitive to various stimuli including those that may cause itching.
These unmyelinated sensory nerves are abundant throughout the skin, particularly in the form of free nerve endings. When activated, they send signals that are processed by our nervous system and perceived as pruritus. Understanding the interaction between these receptors and nerve fibers is essential for grasping how we detect and respond to different tactile stimuli, including itching.