The Immune System
The body is composed of protective substances to make it harder to invade or penetrate. For example, the major openings such as the nose, mouth and eyes are shielded with mucus and fluids to trap organisms from entering the different systems of the body.
The skin also creates protective materials to get rid of pathogenic intruders. The stomach's acid content including the tiny hairs located all over the body is also forms of protective barriers to remove or eliminate organisms who try to attack the body's health. However, when all these fail the immune system will be there to carry out a rescue or act as defenders.
The immune system is an organization of cells, organs and tissues that works together to guard the body from sickness and diseases. Its mechanism identifies any pathogen or harmful organisms from the body's own healthy biological structure and processes. These pathogens may come in the form of virus, parasites, fungi or bacteria. Additionally, the immune system also protects the body from the development of unhealthy structures or tumor cells. When the immune system becomes unsuccessful in keeping the body away from harmful organisms, it seeks them out and kills them. This process may involve the destruction of the infected cells of the body while ignoring the healthy ones.
The body's immune or defense system uses an army comprised of immune cells. These immune cells are the white blood cells or leukocytes that are produced in the bone marrow in large amounts. These immune cells are spread throughout the body from the blood to the lymphatic system. They can consume or destroy pathogenic organisms and infected cells. The immune cells have an exceptional characteristic to retain the information of previous attackers. When the immune cells detect the entrance of previous pathogenic elements, it automatically seeks and destroys them before they can even start affecting the cells or tissues of the body. On the other hand, immune cells still have a different type of defense team that is called antibodies. They function by releasing markers in the form of special proteins onto the destructive organisms for the other immune cells to detect and eventually destroy.
The Different Organs and Cells of the Immune System and their Functions
Bone Marrow – The bone marrow manufactures white blood cells, red blood cells, platelets, B cells, natural killer cells, immature thymocytes, and granulocytes.
In general, all cells of the immune system came from the bone marrow through the process of hematopoiesis. After this course of action, the produced cells from the bone marrow travel out to the different parts of the body where they can continue their growth and maturation.
Spleen – The spleen is composed of T cells, macrophages, B cells, natural killer cells, red blood cells and dendritic cells. This organ filters the blood and capture unfamiliar materials that are called antigens. Antigens can come from the external environment or made by the body. An immune response will take place when the antigen is detected to be foreign and possibly harmful. The immune response happens when the dendritic cells or macrophage brings the antigen to the attention of the B or T cells. The spleen also functions as the breeding ground for the B cells to produce large quantities of antibody and the area where aged red blood cells are destroyed.
Thymus – The thymus creates mature T cells from immature thymocytes. The thymus screens out potential T cells that can provide a harmful autoimmune response while the healthy T cells are secured for used by the immune system and are released to the bloodstream.
Lymph Nodes – The Lymph nodes filters lymph or also known as bodily fluids. They are located in the different parts of the body and are composed of B cells, T cells, macrophages and dendritic cells. The lymph nodes screen the fluids while draining them out from the majority of the body's tissues. After sorting out antigens or foreign substances, the lymph are released into the circulation. Captured antigens are given to the B and T cells where an immune response will take place.
The Cells of the Immune System and their Functions
T- Cells – T-cells can be found in the blood, reproductive tracts, lungs, liver and intestinal tracts. It boosts the immune response by activating other leukocytes or white blood cells to help in fighting infections. T-cells also detect and destroy particular tumor cells, parasites and viral-infected cells.
B-Cells – B-cells produce antibodies as a response to invaders and tumor cells.
Natural Killer Cells – NK cells kill abnormal growths such as tumor cells in the form of melanomas, parasites, viral-infected cells, and lymphomas.
Dendritic Cells – These cells can be found in the spleen, thymus, lymph nodes, and the bloodstream. They filter antigens and bring them to the lymphoid organs for an immune response.
Granulocytes – Granulocytes are made of the cells, basophils, neutrophils and eosinophils. They are a different form of white blood cells or leukocytes that destroy parasites and bacteria.
Macrophages – These cells consume foreign invaders and present them to the different defense cells for an immune response. They also play a vital role in regulating the different immune responses.