The dynamics of capsaicin binding with this transmembrane ion channel is unusual in that the molecule remains bound for a long time. Capsaicin molecules bind to a transmembrane ion channel in nociceptors that is sensitive to temperatures above 37☌. For example, the sensation of heat associated with spicy foods involves capsaicin, the active molecule in hot peppers. Stressed or damaged tissues release chemicals that activate receptor proteins in the nociceptors. Mechanical, chemical, or thermal stimuli beyond a set threshold will elicit painful sensations. Nociception is the sensation of potentially damaging stimuli. Some thermoreceptors are sensitive to just cold and others to just heat. Temperature receptors are stimulated when local temperatures differ from body temperature. These two modalities use thermoreceptors and nociceptors to transduce temperature and pain stimuli, respectively. Two types of somatosensory signals that are transduced by free nerve endings are pain and temperature. There are many types of sensory receptors located in the skin, each attuned to specific touch-related stimuli. Many of the somatosensory receptors are located in the skin, but receptors are also found in muscles, tendons, joint capsules, ligaments, and in the walls of visceral organs. This means that its receptors are not associated with a specialized organ, but are instead spread throughout the body in a variety of organs (Fig.2.1.1). These modalities include pressure, vibration, light touch, tickle, itch, temperature, pain, proprioception, and kinesthesia. Somatosensation is the group of sensory modalities that are associated with touch, proprioception, and interoception. Somatosensation is considered a general sense, as opposed to the special senses discussed in this section. Know the primary categories of cutaneous senses: mechanical, thermal, and noxious. Know that somatosensation includes touch (mechanical and thermal), pain (mechanical, thermal, chemical) & proprioception (sense of self-the topic of the next chapter).
0 Comments
Leave a Reply. |