The Immune System
Your Immune System The main function of the immune system is to protect the host from harmful environmental factors such as microbes or chemicals, which preserves the integrity of the body. Components of your Immune System White blood cells are also called leukocytes. They circulate in the body in blood vessels and the lymphatic vessels that parallel the veins and arteries. White blood cells are on constant patrol and looking for pathogens. When they find a target, they begin to multiply and send signals out to other cell types to do the same. Our white blood cells are stored in different places in the body, which are referred to as lymphoid organs. These include the following: Thymus — a gland between the lungs and just below the neck. Spleen — an organ that filters the blood. It sits in the upper left of the abdomen. Bone marrow — found in the center of the bones, it also produces red blood cells. Lymph nodes —small glands positioned throughout the body, linked by lymphatic vessels. Immunity - 3 Types Innate immunity We are all born with some level of immunity to invaders. Human immune systems, similarly to those of many animals, will attack foreign invaders from day one. This innate immunity includes the external barriers of our body — the first line of defense against pathogens — such as the skin and mucous membranes of the throat and gut. This response is more general and non-specific. If the pathogen manages to dodge the innate immune system, adaptive or acquired immunity kicks in. Adaptive (acquired) immunity This protect from pathogens develops as we go through life. As we are exposed to diseases or get vaccinated, we build up a library of antibodies to different pathogens. This is sometimes referred to as immunological memory because our immune system remembers previous enemies. Passive immunity This type of immunity is “borrowed” from another source, but it does not last indefinitely. For instance, a baby receives [...]