in this video, we're going to begin our introduction to the classes of signaling receptors. And so recall from our previous lesson videos that receptors are biomolecules, typically proteins that are going to change confirmation when bound to a very specific like and or signaling molecule. And so it turns out that receptors can be categorized into two major classes. The first class are cell surface receptors and the second class, our interest, cellular receptors and so moving forward. In our course, we're going to talk about the cell surface receptors and the intracellular receptors in their own separate videos. But we'll start off with the cell surface receptors, so I'll see you all in our next videos to talk more about these cell surface receptors.