One concept that I learned in our lesson today is the immune system, which fights against invading disease-causing microorganisms. Learning and understanding how this system works are necessary for us in order to keep our bodies healthy. Having a background in this will help us obtain a well-functioning immune system that can protect our body against pathogens, especially during the COVID-19 pandemic. Moreover, with knowledge on the immune system, it will be easier for us to come up with strategies or ways that can enhance our immunity.