Immune System

        The role of the Immune System is to protect the human body against infection. Cells have special proteins on their plasma membrane surfaces which are able to able to identify foreign invaders and separate the invaders from body’s proteins. Overall, its job is to maintain a dynamic equilibrium in the body. This is when an organism maintains stability, or the internal and external environments of an organism are in homeostasis. Many organisms maintain homeostasis by negative feedback mechanism. When conditions of the body change, the feedback system is triggered. When one change occurs in a system, another change will occur in another part of the system to correct the first change. Once the first change is corrected, the second system will alert the other system to shut down and the second system will also shut down following it. Many diseases result from the breakdown of an organism’s ability to sustain equilibrium. The cause for diseases lies in microbes, which are harmful. Pathogens are disease-causing microbes that include bacteria, worms, etc. Disease can also be caused by a genetic mutation in the body. One cell may have a genetic mutation that causes it to behave normally and unfortunately, these cells may start to divide uncontrollably which can spread this mutation to other parts of the human body. This is known as Cancer. These cancer cells start taking over “normal cells” and cancer can become life threatening. Factors such as radiation, smoking, and an unhealthy diet can lead to cancer. Our bodies try to protect us from invading pathogens and diseases with the help of the immune system. The immune system prevents harmful microbes from getting into the body by blocking their entry. The skin and secretions of the body help to block harmful microbes from entering the body. Sometimes though, some of these microorganisms may enter, and then the immune system must destroy them. Invaders are destroyed by special cells in the body engulfing the microorganism, or by being marked for destruction. The immune system is made of up of specialized white blood cells. Every day, billions of monocytes and granulocytes are released from bone marrow into the blood. Monocytes circulate in the blood for about 24 hours, and then they migrate to different organs such as the liver, and lymph tissues. After monocytes migrate, they are known as macrophages, which is a type of a white blood cell. Macrophages aid in antigen processing. Antigens are foreign macromolecules that don’t belong to the host organism. Antigens help to get rid of a pathogen, with the aid of an antibody. Antibodies later on also destroy the antigen. Macrophages also aid in phagocytosis, which is the process of engulfing large particles of food, which is another way that antigens are destroyed. The two major cells of the immune system are the lymphocytes; also known as the B cells and the T cells, which are also white blood cells. The two cells have very different functions: the B cell patrol the blood and the lymph for any pathogens and produce specific antibodies that go against harmful microbes, like antigens. The T cells respond to the call of B cells when they are alerted that invaders have passed the barrier. Antibodies have a chemical structure that matches them with certain antigens. Once this match is made, the invading pathogen is destroyed. Most of the immune system’s function is to distinguish between the foreign proteins, and the body’s proteins. To battle pathogens, many vaccines have been given to prevent them. Vaccines are weakened pathogens or its antigen that is injected into an organism. Vaccines are given to organisms to provide immunity for a particular pathogen. Antigens are recognized by the immune system and when that happens, the invading antigens cause antibodies to be created to fight against the pathogen. The cells that created the antibodies become “memory cells.” For this reason, if the same pathogen happens to invade the body again, the cells can automatically take out the pathogen before they have a chance to cause any symptoms. This is an example of how vaccines provide active acquired immunity. There are also many types of immunity to disease that a person can acquire. Acquired immunity can either be active or passive. In active immunity, the person is directly exposed to the pathogen or antigen. In this type of immunity, the person produces their own antibodies against the disease. In passive immunity, a person must get antibodies from another organism. They do not use their own antibodies to go against the disease. Innate immunity is when a person is born with immunity to a certain disease.  There is no relationship of exposure between the person and the pathogen. Unfortunately, there is a weakness in overusing antibiotics. As antibiotics are used more often, the immune system slowly weakens. An example of an immune system disorder is HIV {human immunodeficiency virus}, which damages the immune system by destroying the T cells, which leaves the person at a vulnerable state with pathogens. HIV causes AIDS which puts the person’s life in risk. A disease that can kill a person with AIDS can probably be defeated by the immune system of a healthy person. Therefore, overusing antibiotics is not recommended as it weakens the immune system over time. Depending on different people, immune systems can overreact to different antigens that are mostly harmless to other people. These reactions that different people have are known as allergies. An allergic reaction is really a strong response to an allergen such as pollen, animal fur, foods, etc. Symptoms of an allergic reaction are as harmless as sneezing and coughing to something harmful like not being able to breathe or wheezing. These symptoms are caused by histamines, which are the body’s release of substances. These symptoms are actually the body’s way of trying to get rid of an invading antigen. In conclusion, the immune system’s job is to protect the body from harmful pathogens and invading antigens and maintain homeostasis in the body.