Have you ever wondered how your body works? Did you ever think about how your body defends itself from outside invaders? Remember the last time you were sick. Did you know how your body fought and killed the sickness? All these questions can be answered by learning about one of the most important systems in your body, the immune system.
Right now your immune system is at work. Think about it, millions of cells right now are at work inside you. It’s a complex system constantly on that keeps you healthy and at your fullest. This system is made of many organs, cell, tissues and other structures (that work very precisely with each other). Before you learn how the system works, you need to know how about what it defends against.
The immune system defends against foreign invaders. These invaders are called pathogens. A pathogen is any agent that causes disease. These pathogens can come from many places. Many common places are from bacteria, viruses, protists, fungi, and cells from other beings. These pathogens can also spread in many ways, namely air, food, water, contact with an infected animal or plant. (Modern Biology)
One of the main defenses against these pathogens is specific types of cells that have unique functions that aid in destroying a threat. These cells are called Lymphocytes. There are three major types of these cells, the B-cell, Helper-T cell, and Natural Killer cells. The first cell, the B-cell, is matured in the bone marrow. The B-cell makes antibodies that attach to the pathogen. When pathogens invade the body, they usually have a unique structure on the outside of their body. These structures are called antigens. Antigens are what pathogens use to land on a uninfected cell and transfer the virus to it. Antibodies are proteins that attach to the antigen with a complementary shape. These are important because pathogens covered with antibodies are able to be identified by other cells as bad and they will not be able to reproduce and spread the disease because its landing sites are blocked. The next cells are the T cells. There are many different types of T-cells. One is the Killer T-cell. They can recognize invaders with feelers on the outside of the cell and if the cell is infected, it can destroy the cell. Another type is the helper T-cell. The helper t-cell functions more as support. It matures B-cells and tells them to make antibodies by secreting a protein. A helper t-cell also activates the killer t-cell. The last major t-cell is the memory t-cell. If you get sick, the memory t-cell will remember the antigen and will the immune system be able to defeat the same disease faster. The next cell is the Natural Killer Cell. These cells are lymphocytes that destroy viruses by releasing a protein that makes the affected cell “program” itself for death. The process it destroys itself is called apoptosis. (Kidshealth.org)
Another type of cells that protect your body is the Phagocytes. Phagocytes are types of...