For the skin, we actually have a two types of skin. Okay, [FOREIGN]. One is actually the hairy skin, just your [FOREIGN] and the other one, glabrous skin, [FOREIGN] is opaque, something to see the. Okay, they, for this to type of skin, of course, actually, the sensory system are a little bit different. All right. [FOREIGN] Let's take a look, actually, at the structure, as I mention for the skin, the wider to the epidermis. This is p. And then, this is damaged. [FOREIGN] For most of those types, sensation. Mechanical neuron. Actually, it's a way to the [INAUDIBLE]. The largest one is this one. This [INAUDIBLE]. [FOREIGN] This guy. This one actually [FOREIGN]. The meter. [FOREIGN], okay. This guy [FOREIGN] is some kind of special cells. Actually, it's kind of wrapped many, many times, and they make the structure. And this fiber, this is actually the neural fiber, okay? The neural fiber actually is going to the middle, wrapped by those structure. And this guy, actually kind of located quite deep in the dermis. And this one, actually, is responsible for the high frequency vibration of your skin. [FOREIGN] Detect the information okay. [FOREIGN] We'll talk about the properties of this cell. And this one is smaller than this guy, there are ending, here, they are smaller, but actually they are quite large compared to the other guys. And also, for this one, this structure is quite special, okay? [INAUDIBLE] For this guy, actually, take a look. They kind of, on the surface of this dermis, right? And they actually, they are on this kind of reach [FOREIGN]. Okay. For this one, we talked about actually the hair follicle receptor surrounding the hair, right? This is the nerve ending. And then, for this axon fiber, as we mentioned, there are quite a few different types. And actually, for this structure. There are two types, okay? One is actually is into this scheme, from the scheme, then the [INAUDIBLE] actually, is the frown. Alpha beta then the delta, then the C fiber, okay? But, for those actual in the way to choose a muscle, they have a different name, corresponding it to group one, two, four. They have fiber, actually, quite large. We mentioned it, right? It's the largest one, the fiber. [FOREIGN] Fiber axle. And the outside is [FOREIGN]. So among this, only the c fiber actually [FOREIGN]. And the c fiber, also, is the smallest one. For the c fiber, we mentioned, actually, mainly responsible for the pain sensation. And also, the temperature and the each. Also, can be sensed by the C fiber. C fiber has the free ending in the skin. And for this fiber, and then they are responsible for the pain. And the temperature sensation. And for a beta fiber, and then they're mainly for the mechanosensation of the skin. A alpha then is mainly responsible for the muscle. [FOREIGN] Because the fiber, the diameter and also the outside surrounded by or not. So, their speed for the spike propagation. They're different. So, what kind of relation between the diameter and the cephalic propagation speed? [FOREIGN] >> [INAUDIBLE] >> [FOREIGN] >> [FOREIGN] >> [FOREIGN] >> [INAUDIBLE] >> Okay. >> [FOREIGN] >> The simple way would be the larger the diameter, and the fast the traveling, right? So, for the c fiber, take a look here. C fiber, this bit uses the slowest one, of course, and then there is about 0.52 to meter per second. [FOREIGN] Okay? [FOREIGN] So, based on this information, then you will know. There are two kinds of pain there. Because a beta carries a pain sensation. And the c fiber also carries a pain sensation. But their speed are different. Link to your experience. Whether you have this kind of experience about the given pain. [FOREIGN] So, those are related to the of the action potential propagation. So, this table then summarize, actually, the whole information here. And we have a beta It's responsible for the mechanical and the [INAUDIBLE] joints. And the beta, this one, is for the mechano sensation, mainly for touch, okay? And also for the temperature on the c fiber. And for this actually, it's not like the other system where you really understand a lot. But for this study, basically, people study for quite long, okay? It's just actually too much details inside for this study. And for example, for this site, for example the fibers, also for the response for this, they have specialties. Some of these touch, for example, you will have very fast adaptation. Now, you got [FOREIGN]. That's called adaptation. Here, I guess, actually, for this mechano touch, we have two kinds of neurons. One is for rapid adaptation. One is for slow adaptation. Let me show you what I am talking about. There are two waves of pain, so, if you have a stimulation, and then you will feel basically, two kinds of pain. The first one, actually, is a sharp pain, okay? And this carried by the A delta fiber in your skin. And again, this pain finish, then you will follow a more slowly developed [INAUDIBLE] sharp pain [FOREIGN] dedicate the second [INAUDIBLE] carried by the c fiber, okay?
