Final answer:
When bacteria are exposed to a B cell in the spleen, they initiate a humoral immune response. This response leads to the production of antibodies by plasma cells that originate from activated B cells. Memory B cells are also generated to provide a quicker response upon future infections.
Step-by-step explanation:
If bacteria are exposed to a B cell in the spleen, they will initiate a humoral immune response. This response is primarily associated with B cells which, upon encountering an antigen, differentiate into antibody-secreting plasma cells. The antibodies that these plasma cells produce can neutralize pathogens directly or mark them for destruction by other parts of the immune system. In contrast to the humoral response, the cell-mediated immune response involves T cells that directly attack infected cells or coordinate the overall immune response.
The humoral immune response does not just involve the activation of B cells to fight off pathogens but also leads to the creation of memory B cells. These memory cells remain in the body after the initial immune response and enable a faster and stronger attack on the pathogen if it invades the body again in the future.