Immune System

The immune system is a system of biological structures and processes within an organism that protects against disease. To function properly, an immune system must detect a wide variety of agents, from viruses to parasitic worms, and distinguish them from the organism's own healthy tissue.

Pathogens can rapidly evolve and adapt to avoid detection and neutralization by the immune system. As a result, multiple defense mechanisms have also evolved to recognize and neutralize pathogens. Even simple unicellular organisms such as bacteria possess a rudimentary immune system, in the form of enzymes that protect against bacteriophage infections. Other basic immune mechanisms evolved in ancient eukaryotes and remain in their modern descendants, such as plants and insects. These mechanisms include phagocytosis, antimicrobial peptides called defensins, and the complement system. Jawed vertebrates, including humans, have even more sophisticated defense mechanisms, including the ability to adapt over time to recognize specific pathogens more efficiently. Adaptive (or acquired) immunity creates immunological memory after an initial response to a specific pathogen, leading to an enhanced response to subsequent encounters with that same pathogen. This process of acquired immunity is the basis of vaccination.

Disorders of the immune system can result in autoimmune diseases, inflammatory diseases and cancer. Immunodeficiency occurs when the immune system is less active than normal, resulting in recurring and life-threatening infections. In humans, immunodeficiency can either be the result of a genetic disease such as severe combined immunodeficiency, acquired conditions such as HIV/AIDS, or the use of immunosuppressive medication. In contrast, autoimmunity results from a hyperactive immune system attacking normal tissues as if they were foreign organisms. Common autoimmune diseases include Hashimoto's thyroiditis, rheumatoid arthritis, diabetes mellitus type 1, and systemic lupus erythematosus. Immunology covers the study of all aspects of the immune system.

Read more about Immune System:  History of Immunology, Layered Defense, Surface Barriers, Innate Immune System, Adaptive Immune System, Disorders of Human Immunity, Other Mechanisms, Tumor Immunology, Physiological Regulation, Manipulation in Medicine, Manipulation By Pathogens

Other articles related to "immune system, immune, system":

... is a biotechnology company developing and manufacturing products that use the immune system for predicting and managing human health ... protected, FDA-approved cellular assay of immune system function, trademarked as ImmuKnow, that measures the vitality of a patient's immune system from a single drop of blood ...
Immune System - Manipulation By Pathogens
... The success of any pathogen depends on its ability to elude host immune responses ... them to successfully infect a host, while evading detection or destruction by the immune system ... enzymes that digest the barrier, for example, by using a type II secretion system ...
La Jolla Institute For Allergy And Immunology - Research - Automimmune Research
... which can be triggered when the body's immune system begins to attack healthy cells ... requires an understanding of how to turn off an immune system attack, which might seem an unusual goal ... After all, most immune onslaughts are aimed at viruses, bacteria or other biological invaders to the body ...
Long-term Effects Of Benzodiazepines - Symptoms - Immune System
... with resultant long-lasting disturbances to behaviour, endocrine function and immune function ...
Cancer In Cats - Treatment - Treatment Methods - Medical Based Treatment
... works on the premise that many cancers occur because of a defect in the organism's immune system ... It asserts that the tumor would have been suppressed, had the organism's immune system been functioning normally ... external procedures, it stimulates the animal's own system to fight the cancer ...

Famous quotes related to immune system:

    The moral immune system of this country has been weakened and attacked, and the AIDS virus is the perfect metaphor for it. The malignant neglect of the last twelve years has led to breakdown of our country’s immune system, environmentally, culturally, politically, spiritually and physically.
    Barbra Streisand (b. 1942)