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Definition: Immune system from Encyclopedia of Alzheimer's Disease: With Directories of Research, Treatment and Care Facilities

The immune system is a constellation of organs and blood cells that work together to protect us from disease. Immune system organs include the bone marrow, lymph glands, spleen, appendix, tonsils, and adenoids. The key players of the immune system are white blood cells, primarily lymphocytes and macrophages. Immune system cells travel to locations in the body where they perceive a foreign threat, usually an infectious agent or an allergen. Here they release factors that result in inflammation. Immune system cells also produce antibodies to fight the foreign agent during a subsequent attack.

Immune System

From The Human Body Book: An Illustrated Guide to Its Structure, Function and Disorders
The adaptable system of body defences centres on specialized white blood cells called lymphocytes. These respond to invasion by varied microorganisms. The complexities of the system aim to create the condition of immunity, in which, after the first attack, the body is protected or resistant to future incursions by each particular type of microorganism. The lymph nodes (or “glands”) are vital to the body’s defence system – they produce and harbour immune cells (lymphocytes) that protect the body from disease. Lymph nodes are scattered throughout the body and also concentrated in groups (see illustration ). Each node is a mass of lymphatic tissue divided into compartments by partitions of connective tissue known as trabeculae. Lymph fluid from most tissues or organs flows through one or more lymph nodes, where it is filtered and cleaned, before draining into the venous bloodstream. Several smaller lymphatics (vessels) bring lymph to the node, and one larger vessel carries it away. The…
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Full text Article Explainer: How the human body first fights off pathogens (May 2018)

From The Conversation: An Independent Source of Analysis from Academic Researchers
Thermal scanner in use at Manila’s International Airport during a MERS outbreak in 2014.
People constantly encounter viruses, bacteria or parasites. Fortunately, our skin, the specialized lining of our guts and other parts of our body that are exposed to the outside world prevent them from entering. When a pathogen breaches this barrier, our body’s defences come into play. Those…
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Full text Article Lymph and Immune Systems

From The Human Body Book: An Illustrated Guide to Its Structure, Function and Disorders Full text Article Lymph and Immunity
Lymph and Immune Systems
Several systems of the body help to defend it against various hazards – such as the sun’s ultraviolet rays, excessive heat, harmful chemicals, physical damage, and the threat of microorganisms such as bacteria and viruses. However, the immune system, incorporating the lymphatic system, is the main…
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Full text Article immune system

From Library of Health and Living: The Encyclopedia of Men's Health
The organs, tissues, cells, chemicals, and functions that protect the body from infection and disease. The immune system's primary organs are the skin , thymus , spleen , bone marrow , and white blood cells . Other components of the immune system are the lymphatic system and secondary lymphoid…
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Full text Article Immune System

From The Gale Encyclopedia of Senior Health
The organs of the immune system are located...
The immune system is a complex network of cells, tissues, and organs that function cooperatively to protect the body (sometimes called the host organism within this context) from invasion by bacteria, viruses, parasites, fungi, toxins, and tumor cells (pathogens). When an immune system is healthy…
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Full text Article Immune System

From Gale Encyclopedia of Children's Health: Infancy Through Adolescence
The immune system is the mechanism that protects the body from foreign substances, foreign cells, and disease-causing microorganism (pathogens). The thymus, spleen, lymph nodes, antibodies, and white blood cells, including the B-cells and T-cells, are involved in the immune response, which aims to…
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Full text Article immune system

From The Penguin Dictionary of Science
A defence system found in organisms to protect against danger, including sterile injury, foreign organisms, such as ➤ viruses and ➤ bacteria , and cancer. The effector cells that form the immune system include the ➤ leucocytes , such as neutrophils and ➤ macrophages , which engulf and digest cell…
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Full text Article Immune System

From The Gale Encyclopedia of Fitness
The immune system is composed of cells, organs, tissues, and molecules that protect the body from disease. The term “immunity” comes from the Latin word immunitas . It is roughly divided into two branches, “innate immunity” and “acquired (adaptive) immunity.” These two branches may interact to…
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Full text Article Immune System

From The International Encyclopedia of Depression
Depression has been linked to a variety of chronic medical conditions, including heart disease, stroke, Alzheimer’s disease, diabetes, some cancers, obesity, arthritis, and osteoporosis. The prevalence of depression among patients with these conditions is generally higher than the prevalence of…
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Full text Article immune system

From Britannica Concise Encyclopedia
Cells, cell products, organs, and structures of the body involved in the detection and destruction of foreign invaders, such as bacteria, viruses, and cancer cells. Immunity is based on the system’s ability to launch a defense against such invaders. For the system to function properly, it must be…
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Full text Article Immune System

From Gale Encyclopedia of Nursing and Allied Health
Immune system.
The immune system is composed of cells, organs, tissues, and molecules that protect the body from disease. The term “immunity” comes from the Latin word immunitas . It is roughly divided into two branches, “innate immunity” and “acquired (adaptive) immunity.” These two branches may interact to…
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