 Now, another strategy in the toolkit for the innate immune system is nonspecific phagocytosis, just by the name of it. The fact that we're calling it nonspecific probably gives you an idea that there must also therefore be specific phagocytosis. And that's part of, again, very specific, only this antigen. It's the only one that I will phagocytize or yumptialize the endocytose, and so that's a process that's a different form of phagocytosis that will occur. Nonspecific, notice that we should probably think about who does this? Who would eat just anything that comes along? Well, the men do. The monocytes or macrophages when the macmonocytes, white blood cells move out of the bloodstream and into the tissues. Phagocinophils, another form of phagocytotic, phagocytic, white blood cell, and the neutrophils, who are also capable of nonspecific phagocytosis. So the men do this. Now, how do they know? How do they know what to eat? Well, this is a hugely important question. I'm going to draw you a picture of a bacteria. This is some bacteria, whatever, it's a pathogen. It's a bad guy. And we're cool. They're covered with antigens. They're covered. Any invading thing is going to be covered with markers, its own self-markers and its cell membrane, and some of those might stimulate an immune response and some of them might not. Nonspecific phagocytosis responds to specific markers on a pathogen and they're called PAMPs. But of course they are. And a patient, associated, molecular. Now think about this for a minute. It's a pattern of whatever protein, amino acids stuck together, carbohydrates hanging off the side, whatever it is, we know it's associated with pathogens. So if you come across something like this, if you come across a PAMP, if the men come across the PAMP, they're going to know, hey, that's most likely a bad guy, I'm just going to yumpsha-lize it right now. Game out, like why even bother calling in the troops? I'm just going to eat this thing, like let's get rid of it. Because I recognize this molecule. My analogy for this, if you saw an animal, you don't know what kind of animal it is, but it's wearing earrings. That would be like some kind of marker and its earrings are associated with humans. I mean, you don't very often see like chimpanzees with their earrings on or any other critter other than humans wearing earrings on this planet. So that would be all humans have earrings. So not all pathogens are going to have these markers. But if you see this marker, you're pretty well sure, whatever I just said, that it is a human, a pathogen, so eat it. Now, how do the nonspecific phagocytes, the men, how do they know that, I mean, go ahead and think about this. What's the next piece? What's necessary in my men in order to respond? Really, your little brain, your giant, brilliant brain is like, dude, we better have some kind of a receptor in our nonspecific phagocyte. So this is a amen, one of them, amen. And guess what this thing is called? Because of course it has a name. This type of receptor, all it is is a receptor. It's just another protein that's found in the cell membrane of the men. And this one is called a pattern, okay, it's called a PRR, PRR, pattern recognition receptor. Okay, I'm cool. It's a receptor, that one I'll remember. The pattern, I will remember that it recognizes the pattern. It recognizes, look, pattern here, pattern here. Here's my pattern, that thing's my pattern. This is my pattern recognition receptor. That's recognizing the pattern. And it's like having earring receptor recognizers. So if you had a little machine that could go out and say, oh, there's some earrings, oh, there's some earrings, and you just go out and like check everybody to see who has earrings, you would know that if you've got earrings, you're a human. And if you don't have earrings, nobody knows what you are, but we're not going to yumpshelize you. And hopefully, if you have earrings, you're not going to get yumpshelized either. Okay, do you follow that? Little process, that's just the mechanism. Yeah, that's one mechanism. The next mechanism is a little bit easier. There are all sorts of things that can initiate phagocytosis. A chemical that says, hey, over here, phagocytize this man. A chemical that initiates phagocytosis. And guess what? Guess who can act as an opsonin? Antibodies. Antibodies, so let's just pretend like this little guy right here also had a protein, an antigen in its cell membrane. It's a bad guy. And then along comes an antibody that binds to that. So I'm going to make my little, okay, look at how, please tell me you're like, oh yeah, I totally get that, because look at what, it's tiny, really, whatever. There's an antibody with a little matching piece to that specific antigen. If a pathogen gets covered with antibodies, that's another way that non-specific phagocytosis can be initiated. So any chemical that initiates phagocytosis can be an opsonin, and antibodies can act as opsonins. Did you follow that whole thing? All right, so those are two ways that we can strategize to get things eaten. Now we're going to talk about our friends, the natural killers. They've got a whole other strategy, and I'm telling you right now, don't mess with the natural killers.