A Definition of the Immune System
To explain how the immune system functions, let’s start with describing what the immune system is and how it works. The immune system consists of a network of cells, proteins, tissues, and organs that work together to protect our bodies from infectious microorganisms including bacteria, viruses, and fungi. The main function of the immune system is to ward off invaders in order to protect the body from infection. In fact, when our bodies have an immune response, our immune systems attack the invaders that can harm our other body systems and cause illness or disease.
The organs that are involved with our immune system, called the lymphoid organs, affect growth, development, and the release of lymphocytes, or infection-fighting white blood cells. Lymphoid organs include the adenoids, appendix, blood vessels, bone marrow, lymph nodes, lymphatic vessels, spleen, thymus, and tonsils. All lymphoid organs are important to the immune response because they are involved in producing and activating lymphocytes, which are a key component of an effective immune system.
The immune system has several responsibilities, including protecting our bodies from infection through natural barriers and adapting itself to provide immunity against infection by remembering invaders from previous exposures. One function of the immune system is that it creates natural immunity through the body’s own barriers, like the skin, saliva, and mucus in the mouth, urinary tract, and on the surface of the eye. Natural immunity also is created when a mother passes antibodies to her child.
Natural immunity occurs when we are able to resist illnesses thanks to a healthy immune system. Natural immunity also is the reason behind infants’ immune systems having the ability to distinguish between self and non-self, so that his immune system only attacks harmful elements. Thus, infants fight several common illnesses because of natural immunity.
Acquired immunity is another function of the immune system. Over time, the body develops acquired immunity. Acquired immunity builds up when people get ill and the immune system’s memory cells learn to identify the illness, remember it, and fight it in future instances. Our immune systems acquire immunity as we are exposed to foreign microorganisms, toxins, and foreign tissues. Acquired immunity is the reason vaccines are effective; the immune system is exposed to the illness, produces antibodies against it, and then triggers the release of those specific antibodies when the body is exposed to the illness again.
Producing Excess Mucus
Mucus is a part of the body’s first line of defense against intruders. For example, when our bodies detect a common rhinovirus cold, our immune systems trigger membranes to produce excessive amounts of mucus to first prevent further intrusions and then to flush out the ones that already are in the body. So, the next time you get a runny nose, you should appreciate your immune system for doing its job. Image via Flickr by William Brawley
Increasing Body Temperature
You may have had a physician caution you about using medication to lower a low-grade fever, or a grandmother tell you that a mild fever is good for you. While these responses from our caregivers may not be what we want to hear when we aren’t felling well, they actually are correct. Your immune system increases your body temperature in an effort to damage invading microorganisms.
In fact, researchers from Roswell Park Cancer Institute found that higher body temperatures aid our immune systems in more successfully fighting infected cells. Dr. John Wherry, deputy editor of the Journal of Leukocyte Biology, said “this research report and several others are showing that having a fever is part of an effective immune response.” Keep in mind that the research supports being cautious about treating mild fevers, but it is important to treat fevers that are dangerously high.
Increasing Your Cough
Another function of the immune system is triggering an increased cough, to help your body clear your lungs. If you have an excess of mucus or other irritants on the surface of your respiratory tract, your body tries to expel them by propelling them upwards through coughs. Your cough is one more reason you should appreciate your immune system.
Overall, the many functions of the immune system are designed to protect our bodies from infections. The immune system’s cells attack invaders by engulfing bacteria, killing parasites, and killing cells infected by viruses. You may not always notice when your immune system is functioning to protect your health, but your next fever, runny nose, or cough is your immune response doing what it is supposed to do in an effort to keep you healthy.