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- [Voiceover] An individual has lost the ability to activate B cells and mount a humoral immune response. Part A, propose one direct consequence of the loss of B-cell activity on the individual's humoral immune response to the initial exposure to a bacterial pathogen. So, just as a reminder what B cells are, and what a humoral immune response are, a humoral immune response is one that involves antibodies. And B cells are the ones that will recognize an antigen, something that the body doesn't want in its body, and then in response to that, those antigens, it will produce, it will one, it'll proliferate, it'll differentiate into plasma cells that produce antibodies which are essentially these macro molecules that tag the antigens for cleanup, and then it can differentiate into memory B cells. So that next time, when that same antigen shows up it can mount a faster response. So part A, propose one direct consequence of the loss of B-cell activity on the individual's humoral immune response to the initial exposure to a bacterial pathogen. So there won't be a humoral response. So I could say, No, no antibodies, bodies will be produced, so no humoral immune response. So there will be no humoral immune response. Humoral immune, immune response to the initial exposure. To initial, initial exposure. So you're not going to have any tagging of these antigens that then can be cleaned up by other immune cells. None of that's going to happen. Part B, propose one direct consequence of the loss of B-cell activity on the speed of the inidividual's humoral immune response to a second exposure to the bacterial pathogen. Well you have no memory B cells. No memory B cells and no antibodies. Antibodies. Specific or, I could say, for second exposure to pathogen. For second exposure to pathogen. So no humoral response. So no humoral response. And overall immune response will be slower. The whole point of B cells and the antibodies is that the second time it shows around, it gets tagged very quickly. It gets recognized very quickly. And then the immune system can respond. Well now you're not going to have that. You're not going to have this in the secondary exposure, that quick recognition of the antigen. So you're not going to have humoral response, and you could say, overall, overall immune response, immune response will be slower. Immune response is going to be slower and less effective. Slower and less effective. Alright, let's think about part C. Describe one characteristic of the individual's immune response to the bacterial pathogen that is not affected by the loss of B cells. Well the B cells are all about the humoral immune response. It's about tagging things with antibodies, having the memory B cells around so that the next time you get the pathogen, the second exposure, you have a quicker response. But it's not the only part of our immune system. Our immune system has, still, many facets to it. One, you're still going to have the cell mediated immune response. Still have cell mediated, mediated immune response. Immune response. And these are things like phagocytes that will go and engulf, that will engulf the pathogens. Phagocytes. Phagocytes, you have T cells that can recognize the antigen and similarly try to go about destroying the antigen. So you still have the cell mediated immune response. You also have things like the skin, things that just block pathogens from entering your body. And that's considered part of your immune system. Still have skin protection. And you can go into more detail but these are still the types of things that the body has, even if it lost its B cell capability in order to prevent pathogens from entering, in the case of skin, and also still once the pathogens get in, to still recognize them and engulf them or destroy them in some way.