ABOUT YOUR IMMUNE SYSTEM
The immune system is the body’s defence against infectious diseases. It is very important to build a strong immune system in order to activate immune response, so that it can attack foreign substances that invade the body system that causes disease. A strong immune system does a great job of keeping people healthy and preventing infections.
The immune is made up of a network of cells, tissues, and organs that work together to protect the body. One of the most important key player cells involved are white blood cells, also known as leucocytes, which come in two basic types that can combine to seek out and destroy disease-causing substances.
Leucocytes are produced or stored in many locations in the body, namely the lymphoid organs including the thymus, spleen, and bone marrow. There are also clumps of lymphoid tissue throughout the body, primarily as lymph nodes that house the leucocytes.
The two basic types of leucocytes include phagocytes, cells that engulf invading organisms; lymphocytes, cells that allow the body to remember and recognize previous invaders and help the body destroy them. The most common type of phagocytes is neutrophil, which primarily fights bacteria. Doctors usually order a blood test to see if a patient has an increased number of neutrophils if they are worried about a bacterial infection. There are also two kinds of lymphocytes, namely B lymphocytes and T lymphocytes. Lymphocytes start out in the bone marrow and either stay there and mature in B cells, or they leave for the thymus gland, where they mature into T cells. B lymphocytes and T lymphocytes have separate functions: B lymphocytes are like the body’s military intelligence system, seeking out their targets and sending defences to lock onto them. T cells are like the soldiers, destroying the invaders that the intelligence system has identified.
How do immune system work? When antigens (foreign substances that invade the body) are detected, several types of cells work together to recognize them and respond. These cells trigger the B lymphocytes to produce antibodies, which are specialized proteins that lock onto specific antigens. Once produced, these antibodies stay in a person’s body, so that if his or her immune system encounters that antigen again, the antibodies are already there to do their job. This is how immunizations prevent certain diseases. An immunization introduces the body to an antigen in a way that doesn’t make someone sick, but allow the body to produce antibodies that will then protect the person from future attack by the germ or substance that produces that particular disease.
Although antibodies can recognize an antigen and lock onto it, they are not capable of destroying it without help. That’s the job of the T cells, which are park of the system that destroys antigens that have been tagged by antibodies or cells that have been infected or somehow changed. (Some T cells are actually called “killer cells”.) T cells also are involved in helping signal other cells like phagocytes to do their jobs. Antibodies can neutralize toxins too and activate a group of proteins called complement, which assists in killing bacteria, viruses, or infected cells.
All of these specialized cells and parts of the immune system offer the body protection against disease. This protection is called immunity.
Humans have three types of immunity, innate, adaptive, and passive:
Innate immunity, also known as natural immunity is a type of general protection. Everyone is born with innate immunity. It also includes the external barriers of the body, like the skin and mucous membranes (like those that line the nose, throat, and gastrointestinal tract), which are the first line of defense in preventing diseases from entering the body. If this outer defensive wall is broken (as through a cut), the skin attempts to heal the break quickly and special immune cells on the skin attack invading germs.
The second kind of protection is adaptive (or active) immunity, which develops throughout our lives. Adaptive immunity involves the lymphocytes and develops as people are exposes to diseases or immunized against diseases through vaccination.
Passive immunity is “borrowed” from another source and it lasts for a short time. For example, antibodies in a mother’s breast milk give a baby temporary immunity to diseases the mother has been exposed to. This can help protect the baby against infection during the early years of childhood.
With that said, everyone’s immune system however is different. We can see some people never seem to get infections, whereas others seem to be sick all the time. As people grow older, they usually become immune to more germs as the immune system comes into contact with more and more of them. That’s why adults and teens tend to get fewer colds than kids- their bodies have learned to recognize and immediately attack many of the viruses that cause colds. However, this varies from person to person.
Problems of Immune system
Immune system can go haywire sometimes, which could be in the form of immunodeficiency disorders, autoimmune disorders, allergic disorders and cancers of the immune system.
What we’re more interested in looking at is the cancers of immune system. Cancer happens when cells grow out of control. This can include cells of the immune system. When normal cells turn into cancer cells, some of the antigens on their surface may change. If the immune system notices the foreign antigens, it launches the body’s defenders, including killer T cells, NK cells, and macrophages. But the immune system cannot patrol everywhere to provide body wide surveillance, flushing out and eliminating all cells that become cancerous. Tumours develop when the system breaks down or is overwhelmed. For example, Leukaemia involves abnormal overgrowth of leucocytes while Lymphoma involves the lymphoid tissues.