 All right, you tell me, what are the possible blood types that you can have? Go ahead. You can do it. Maybe I can do it. Maybe I can do it. There are four. Do you agree with that? I could have, and I'm going to draw you a blood vessel. I'm going to draw you four of them to show you that these are four different people. I think the way I draw it normally, it is confusing. So, yes, we are drawing four different people. What are my possible blood types? You know this. We have type A blood, we have type B blood, we have type AB blood, and we have type O, right? And I can hear you. I can hear you. I'm like, yell that. What about positive and negative factors? Yeah, we're not going to talk about those yet. We'll talk about those in class because the Rh factor is very interesting and has physiological consequences. But I just want to deal with the general, like, reality of your different possible blood types. Now, are you ready? Do you think there are any blood cells in my type A blood? Of course, all of my blood vessels here are filled with blood, and blood has red blood cells, and these are my red blood cell drawings. Is there anything else in there? Of course, there's, like, millions of blood cells in each one of these, and there's white blood cells, and there's plasma proteins, which means there's also what? Antibodies. It's totally like gobs and gobs of antibodies. We don't care about most antibodies. There are a couple that we do care about. Blood type is determined by the presence of an antigen on the red blood cell. We talked about antigens. They possibly initiate immune responses. Done. What kind of antigen are you going to expect on a type A blood cell? A type A antigen. If you're drawing it this way, they don't really look like little A's. I could draw a shape. I could draw anything, but I'm going to draw the little A so that you know that's a type A antigen that's embedded in the red blood cell. What kind of antigen would you expect in a B type B blood cell? It's going to be a B antigen, right? Super, like, it's easy, done. Doggies, what kind of antigen do you expect in a B blood? The red blood cells have B antigens and A antigens. They have genetics that produce both of those possible markers. What kind of antigens are you going to expect on type O blood? There is no O antigen. It just means the absence of antigens. Type O blood has no A, B antigens embedded in the surface. Does it have no antigens? Dude, it's covered with antigens. There's jillions of them, but all we're talking about are A antigens and B antigens in reference to blood type, so don't be confused. Now, do you think that, okay, you have a couple of antibody options. You can have type A antibodies and you can have type B antibodies. Now, type A antibodies are going to match with type A antigens. That makes perfect sense, right? So type A antibody is going to bind to a type A antigen and what did I say antibodies were going to do? They're going to, like, destroy. Like, if you get tagged by antibodies, somebody's going to come along and eat you and the game is going to be over. So if you have type A blood and you have A antigens all over your red blood cells, do you want type A antibodies in there to attack those A antigens? No, because you'll like your blood will clot into mashed potato land, which is a sad story. So yeah, that's a horrible idea. No. Instead, what kind of antibodies do you think a type A blood person is going to have in their bloodstream? They actually have type B antibodies. Do they have any other antibodies? Yes, they've got jillions of antibodies. So don't be confused. There's jillions of them in there, type A antibodies. Because if there were type A antibodies, we'd attack, combine, and initiate an immune response and you would turn to mashed potato blood. What kind of antibody are you going to find in type B blood? Dude, how easy is this? Anti-A's are going to be in there to attack any foreign antigens. What kind of antibody are you going to find in type B blood? None. Are there no antibodies whatsoever? Of course not. There are totally jillions of antibodies. There just aren't any anti-A's or anti-B's. Does that work for you? Because otherwise you'd attack your blood cells. Bad idea. Don't do it. How about type O? What are you going to have going on in there? You have anti-A's and anti-B's in type O blood. I am not going to go here, but I'm going to let you think about who can donate blood to whom? Like what? Who? Could my type A person donate? Okay, but I have to tell you one more thing. When you donate blood, most of the time you do not donate whole blood. You donate either red blood cells or you donate plasma, so you have to clarify when you're asked a question like this. You have to say, can Joe donate blood to Bob? You have to say, are we talking about whole blood or are we talking about red blood cells or are we talking about plasma? Because the answers are going to be different depending on the case. If you donated whole blood from this guy to this guy, you're going to donate B blood cells that are going to get attacked by those antibodies and you're going to donate A antibodies. They're going to attack these blood cells. That's never going to work. Type B blood people can't donate blood to type A blood people. Can they donate plasma? No, because their antibodies and their plasma are going to attack their cells. Can they donate just blood cells? No, because the antibodies and their plasma are going to attack their blood cells. It's a disaster. Don't do it. What about a type O person? Who can they donate to? Who can they donate red blood cells to? Everybody. It's magic. They have no antigens on their red blood cells so they can go anywhere. It doesn't matter how many antibodies you have in your blood. You aren't going to be able to kill anything because there's nothing there to attach to. All right. This is a good little like prep thing for the immune system that is coming up next. But think it through. There was a lot of information that we just did in blood land. It was a bloody long lecture. I have no idea how long it was, but it seemed like a really long one. Okay, now I'm leaving if I can find the off button. I did. Bye-bye.