Immune System, group of cells, molecules, and organs that act together to defend the body against foreign invaders that may cause disease, such as bacteria, viruses, and fungi. The health of the body is dependent on the immune system’s ability to recognize and then repel or destroy these invaders. The ability of the immune system to mount a response to disease is dependent on many complex interactions between the components of the immune system and the antigens on the invading pathogens, or disease-causing agents.
white blood cells only make up about 1 percent of blood, but their small number belies their immense importance. They play a vital role in the body’s immune system—the primary defense mechanism against invading bacteria, viruses, fungi, and parasites. They often accomplish this goal through direct attack, which usually involves identifying the invading organism as foreign, attaching to it, and then destroying it. This process is referred to as phagocytosis. White blood cells also produce antibodies, which are released into the circulating blood to target and attach to foreign organisms. After attachment, the antibody may neutralize the organism, or it may elicit help from other immune system cells to destroy the foreign substance. There are two varieties of white blood cells, namely lymphocytes and phagocytes, both of which interact with one another and with plasma proteins and other cell types to form the complex and highly effective immune system.
... of white blood cell, and two major classes of lymphocytes are T cells and B cells. T cells are critical immune system cells that help to destroy infected cells and ... destructive immune system cells such as macrophages, neutrophils, and T cells. Antibodies B cells are another critical type of immune system cell. They participate in the removal of foreign ...
Lymphocytes are specialized white blood cells whose function is to identify and destroy invading antigens. All lymphocytes begin as “stem cells” in the bone marrow, the soft tissue that fills most bone cavities, but they mature in two different places. Some lymphocytes mature in the bone marrow and are called B lymphocytes. B lymphocytes, or B cells, make antibodies, which circulate through the blood and other body fluids, binding to antigens and helping to destroy them.
Most contact between antigens and lymphocytes occurs in the lymphoid organs—the lymph nodes, spleen, and tonsils, as well as specialized areas of the intestine and lungs .Mature lymphocytes constantly travel through the blood to the lymphoid organs and then back to the blood again. This recirculation ensures that the body is continuously monitored for invading substances.
White blood cells are the mainstay of the immune system. Some white blood cells, known as phagocytes, play a function in immunity by surrounding, ingesting, and destroying invading bacteria and other foreign organisms in a process called phagocytosis (literally, “cell eating”), which is part of the inflammatory reaction. Phagocytes also play an important role in adaptive immunity in that they attach to invading antigens and deliver them to be destroyed by other components of the adaptive immune system.
When the body is first exposed to an antigen, several days pass before the adaptive immune response becomes active. Immune activity then rises, levels off, and falls. During following exposures to the same antigen, the immune system responds much more quickly and reaches higher levels. Because the first, or primary, immune response is slow, it cannot prevent disease, although it may help in recovery. In contrast, subsequent, or secondary, immune responses usually can prevent disease because the pathogen is detected, attacked, and destroyed before symptoms appear. This complete resistance to disease is called immunity and may be achieved through either active or passive immunization.
There are 2 main types of immunization-
My Audience will know the Importance of Immunizations. INTRODUCTION The Importance of Vaccine Preventable Diseases. ATTENTION GETTER "Fact Texas is ranked last in Immunization coverage rates among the 50 states"B. ESTABLISH THEME Un immunized kids are starting to become a risk factor in our Texas school, to a point where they are starting to exclude students from school activities. C. CREDIBILITY ...
1. Active Immunization
Active immunization occurs when a person’s own immune system is activated and generates a primary immune response. Active immunization can be triggered in two ways, either by natural immunization or by vaccination.
2. Passive Immunization-
passive immunization does not engage the person’s own immune system. Instead, the individual receives antibodies that were created in another person or animal. Such antibodies can be lifesaving when a disease progresses too rapidly for natural immunization to occur. For example, if a person who has not been immunized against tetanus bacteria is exposed to tetanus, the toxin produced by these bacteria would reach a deadly level before a primary immune response could begin. Administering antibodies against tetanus toxin quickly neutralizes the toxin and prevents death.
Passive immunization has two drawbacks: First, the person does not mount an active immune response, so the immunizing effect is temporary and the person is not immune after recovery. Second, if passive immunization is used repeatedly, it occasionally produces side effects.
Vaccination is intentional immunization against a particular disease by the use of vaccines, substances that are structurally similar to the actual disease-producing agents but that do not produce disease themselves. Most vaccines take one of two forms. The first type of vaccine, such as the vaccines for tetanus and whooping cough, contains chemically killed bacteria or other pathogenic organisms. The other type, such as the oral polio vaccine, contains weakened forms of living organisms that have been genetically selected so they do not produce disease.
Immune System Disorders-
Disorders of the immune system can range from the less serious, such as mild allergy, to the life threatening, such as more serious allergy, tissue rejection and immune deficiencies.
1. Tissue Rejection-
The immune system recognizes and attacks anything different from the substances normally present within an individual; even substances that are only slightly different, such as transplanted tissues and organs.
1. What signs and symptoms did Greg exhibit when he was in the house? Some signs and symptoms Greg experienced were thirst, dizziness, and turgor. 2. Was Mrs. Myron correct when she said that Greg was dehydrated? Which signs and symptoms are consistent with this notion? Mrs. Myron thought that it was not necessary to seek medical treatment. Do you think she was correct? I believe Mrs. Myron was ...
When an organ is transplanted, the MHC of the donor organ is recognized as foreign and attacked by the recipient’s immune system. To minimize the chances of tissue rejection, physicians seek transplant donors who share as many MHC genes as possible with the transplant recipient. Even then, most transplant recipients are given drugs to suppress their immune response and prevent rejection of the transplant.
2. Immune Deficiency-
Deficiencies in immune function may be either inherited or acquired. Inherited immune deficiencies usually reflect the failure of a gene important to the generation or function of immune system components.
An infectious agent resulting in fatal immune deficiency is the human immunodeficiency virus (HIV).
This virus causes acquired immunodeficiency syndrome (AIDS) by infecting and eventually destroying helper T cells. Because helper T cells regulate all immune responses, their loss results in an inability to make adaptive immune responses. This complete lack of immune function makes individuals with AIDS highly susceptible to all infectious agents.