# The Organ Systems/Immune

Immune System
Function of System:
Defends the body against infectious organisms and other invaders.
How it aids in homeostasis:
The immune system aids in homeostasis by preventing pathogens from disrupting the body's normal functions. It achieves this in various ways, including adaptive immunity when the body encounters a new pathogen, innate immunity, secreting acids onto the skin, and using mucus membranes to breakdown bacteria.
Image of the system:
Name and function of Major Organs:
The key primary lymphoid organs of the immune system are the thymus and bone marrow, and secondary lymphatic tissues such as the spleen, tonsils, lymph vessels, lymph nodes, adenoids, and skin and liver. Leukocytes (White blood cells) act like independent, single-celled organisms and are the second arm of the innate immune system. The innate leukocytes include the phagocytes (macrophages, neutrophils, and dendritic cells), basophils, and natural killer cells. These cells identify and eliminate pathogens and are also important mediators in the activation of the adaptive immune system.
The cells of the adaptive immune system are special types of leukocytes, called lymphocytes. B cells and T cells are the major types of lymphocytes and are derived from hematopoietic stem cells in the bone marrow. The lymphatic system is a part of the circulatory system, comprising a network of conduits called lymphatic vessels. The lymphatic system has multiple functions such as the transportation of white blood cells to and from the lymph nodes into the bones. Lymphocytes A lymphocyte is a type of white blood cell in the vertebrate immune system. The three major types of lymphocytes are T cells, B cells, and natural killer (NK) cells. T cells (thymus cells) and B cells (bursa-derived cells) are the major cellular components of the adaptive immune response. Leukocytes Cells of the immune system involved in defending the body against both infectious disease and foreign materials. Five different and diverse types of leukocytes exist. Each leukocyte has a specific job and function to fight off different germs and diseases. The first and largest type of leukocyte is called Neutrophils. Neutrophils are some the very first to attack bacteria when it is detected in the body. Interestingly, the pus found around an infection is dead Neutrophils. Basophils are the second and smallest type of Leukocyte. Basophils fight off foreign objects in the body such as animal hair, grass, dust, and mold. Basophils are also responsible for swelling, asthma attacks, hives, etc. The third type is Eosinophils. These leukocytes mainly focus on bacteria and parasites. Eosinophils aid in allergic reactions, trapping harmful intruders and disrupting unfamiliar activities. Eosinophils are special in the fact that they can attack any invader without having to know what it is and have been known to help rebuild tissues and organs. Next, are Lymphocytes. Lymphocytes are in charge of locating altered cells in the body (such as cancer cells or infected cells) and fighting them. T cells and B cells are a type of Lymphocytes that are involved in building antibodies against germs. T cells and B cells will be able to recognize these germs and readily attack them if they are to invade the body again. Finally, Monocytes are the leukocyte that moves around the body to infected areas. Monocytes divide into cells known as macrophages to break down the foreign invader. Any part of the invader that is left behind is given to lymphocytes to build antibodies in case the foreign invader ever invades the body again.
Reference sources (APA):
CELLS AND ORGANS OF THE IMMUNE SYSTEM In-text: ("Cells And Organs Of The Immune System") Your Bibliography: "Cells And Organs Of The Immune System". Boundless. N.p., 2017. Web. 12 Apr. 2017.
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