 The last thing I want to talk about is the cellular mechanism or the physiological mechanism. And a mechanism answers the question, how? How does that happen? So I'm bringing back this picture that we've already drawn on, and I'm going to put a little purple star next to every place where we would possibly have a cellular mechanism in this process. The cellular mechanisms, we're going to see them all over the place because the whole purpose of physio is to talk about how does that happen? How does your body maintain body temperature or blood pressure? How does your brain communicate messages to your biceps? How does your biceps contract in response? How does the thyroid gland affect metabolism? How is the thyroid gland, how is the thyroid hormone produced? All of those how questions involve cellular mechanisms. So if you look at this one, we could go, okay, there's a change that's detected by a sensor. There is a signal generated that is a cellular mechanism. That is, how did that happen? There was some sort of mechanism that made it happen. And a mechanism is going to be that this cell, the molecule binds to the receptor. The receptor changes its shape. The shape change causes a certain molecule to be produced. That molecule causes a certain hormone to be produced and released into the blood. That hormone goes out and does on and on and on and on. And it's so cool because it's like you get to understand not only how you function, but then you get to think about like drugs and treatments for diseases, like how do we do that? We find treatments that sort of target certain mechanisms and fix things that aren't working properly. The message, the output message, often is going to have a cellular mechanism. The process of comparing from an input message to some set point, like that's a cellular mechanism. Do something? Is a cellular mechanism? Like all of that stuff, all of these places are places where molecular activities are happening. Molecular processes are taking place, resulting in big picture function. Okay, that was your very first lecture. And I'm even not even going to talk about where we're going next. Stay tuned because the next lecture is coming up soon. Okay, except you don't care because the next lecture is coming up when you, whatever. My YouTube students stay tuned. My home dog, hometown students, you guys just study. Okay, I'll talk to y'all later. Bye-bye.