 Hello, everybody. So today we're going to talk about the immune system. We actually have two lectures in which we're going to deal with the immune system. I thought maybe I could talk and write at the same time. Wouldn't you think at this stage in the game that I would know the answer to that question? No, you cannot talk and write at the same time. It was okay, wishful thinking. So the immune system, we're talking about the immune system today following up blood because blood was sort of our link between the cardiovascular system and this whole immunity thing. And the immune system really is pretty straightforward. It has one job. Okay, I take that back because nothing in physio is pretty straightforward. However, the function of the immune system is pretty straightforward. The mechanisms by which it carries out the function, something else. But the function is really simple. The immune system recognizes, I'm not going to say recognizes. I'm going to say distinguishes. Distinguishes between self. That says self and non-self. And then it kicks the holy living tar out of non-self. I mean, can't get much easier than that. You can imagine that this is kind of a dangerous system because if you make a mistake and you kick the holy living tar out of self instead of non-self, that's going to be bad. And if you kick the holy living tar out of non-self and there's too much fallout from the tar kicking, then that's going to be bad. Really, the immune system is a pretty interesting place when it comes to overall function. I'm going to go through the entire two lectures and at the very end of the second lecture, we're going to talk about how the immune system is related to homeostasis because you might be like, yeah, we got to keep the invaders out so we can maintain homeostasis or else we're going to die. Yeah, but really the immune system sort of knocks us out of homeostasis in an effort to keep the bad guys out. And it's sort of the damage that results from the techniques of protection that that damage is worth it because the risk of invasion is worse. So the immune system, we're breaking it down into two parts. And what you'll see is that the two parts that we've broken the immune system down into are really not even real. Like most things, I mean humans like to classify things. And it makes it easier for our brains to compartmentalize, but the immune system, there's a huge amount of overlap between these two categories. So our categories are the innate immune system and the acquired. And both of them function in ultimately distinguishing between self and non-self and battling. The innate immune response is general. In other words, and since this is the one we're going to talk about today, we'll identify what that means. Like what does it mean if it is a general response? The innate immune response is present from birth. So you're born with the ability to generate an innate immune response. The innate immune response is very based on inflammation. And again, inflammation is like a pretty dangerous thing and a really detrimental thing. There's a lot of modern conditions, including cardiovascular disease, diabetes, neurogenitive disorders like Alzheimer's disease that are, they think, based in inflammatory trauma. Like the inflammation is actually what's causing that long-term chronic disease state. So that's like kind of disturbing. It's fast. So as soon as the invader appears, if we can recognize quickly enough that it is an invader, we can initiate this really speedy response. And it utilizes the same strategies. In other words, it doesn't matter who you are. It doesn't matter what kind of an enemy you are, the approach to fighting the enemy is going to be exactly the same every single time, no matter who you are. The acquired immune response is very specific. In other words, we initiate an acquired immune response in response to a very specific invader. And we have a whole herd of possible invaders we can respond to, which is mind-blowing in and of itself. But you can't, it's not, you got to wait for the specific guy to show up before we can launch the acquired response. It's slower. And so it's usually the acquired immune response is how you get over something, because it's actually, it's slow, but it's powerful. And it has memory. So you can actually build it over time. And the acquired immune response is the physiology behind the use of vaccines. Vaccines take advantage of our acquired immune response to give us immunity against various conditions without even having to go through the disease. And I think that's all I want to tell you about the immune system overall. Now, we're going to look at several characteristics of the innate immune response. And I've listed them all out. And the only thing that isn't like a strategy of the innate immune response is the MHC one section of this conversation. And that's a tool. That's a molecule that we have to spend a little bit of time talking about. Other than that, everything else we're going to talk about is a strategy employed by the innate immune system. All right. I'm going to get some water. I'll be right back.