In this video, we're going to begin our discussion on antibodies. Now, antibodies play a big role in immunity and, for that reason, before we actually talk directly about antibodies, we're first going to do a summary on immunity to give you guys a little bit of context. Now, it's important to know that organisms are continually subject to attack by pathogens that cause disease. And for that reason, it's important that organisms have a complex immune system to help defend against these pathogens that are constantly attacking. There are two general types of immunity: innate immunity, which acts as the first line of defense, and adaptive immunity, which acts as the second line of defense.
Innate immunity, because it acts as the first line of defense, is a more generalized nonspecific immunity that's used against all pathogens, and this includes the skin and mucus. Whereas, adaptive immunity, on the other hand, is a much more specific type of immunity with both an adaptive and a memory component and this includes both T cells and B cells. Now, this adaptive immunity can actually be further split into two types. The first is cellular immunity and the second is humoral immunity. Cellular immunity is primarily going to target intracellular pathogens that make their way inside of cells using T cells. And humoral immunity, on the other hand, is primarily going to target extracellular pathogens on the outside of cells using antibodies and B cells. And so, this is the first point here where we're introducing antibodies into our lesson.
Notice down below in our example, we're showing you a more visual display of the immune system summary that we described above. You can see that the immune system can be split into two groups: innate nonspecific immunity, which acts as the first line of defense and includes defense against all pathogens, and includes the skin, mucus, and stomach acid. The second type of immunity is adaptive or specific immunity, which has adaptivity and memory and acts as the second line of defense. This adaptive specific immunity can be further split up into cellular immunity and humoral immunity. Cellular immunity is going to defend inside the cell using T cells, whereas humoral immunity is going to defend outside of the cells using B cells and antibodies. Up above, notice that we're showing you over here on the left a T cell that is going to attack intracellular pathogens. And then on the right, we're showing you a B cell, that is going to attack extracellular pathogens outside the cells. You can see right here is actually the structure of an antibody. We'll be able to talk more about antibodies in our next video. So, now that we've concluded our summary of immunity, I'll see you guys in our next video.