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It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as cancer cells, parasitic worms, and also objects such as wood splinters, distinguishing them from the organism's own healthy tissue. Many species have two major subsystems of the immune system.
Each antibody binds to a specific antigen in a highly specific interaction analogous to a lock and key.. An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as bacteria and viruses, including those that cause disease.
This method of killing invading microbes by using the reactive oxygen-containing molecules is referred to as oxygen-dependent intracellular killing, of which there are two types. [12] The first type is the oxygen-dependent production of a superoxide, [14] which is an oxygen-rich bacteria-killing substance. [33]
An immune response is a physiological reaction which occurs within an organism in the context of inflammation for the purpose of defending against exogenous factors. These include a wide variety of different toxins, viruses, intra- and extracellular bacteria, protozoa, helminths, and fungi which could cause serious problems to the health of the host organism if not cleared from the body.
A hapten is a small molecule that can only induce an immune response when attached to a larger carrier molecule, such as a protein. Antigens can be proteins, polysaccharides, lipids, nucleic acids or other biomolecules. [4] This includes parts (coats, capsules, cell walls, flagella, fimbriae, and toxins) of bacteria, viruses, and other ...
Serum substances that aggregate bacteria and precipitate bacterial toxins: von Gruber and Durham (1896), Kraus (1897) Hemolysins: Serum substances that work with complements to lyse red blood cells: Jules Bordet (1899) Opsonins: Serum substances that coat the outer membrane of foreign substances and enhance the rate of phagocytosis by macrophages
The B lymphocyte activation pathway. B cells function to protect the host by producing antibodies that identify and neutralize foreign objects like bacteria and viruses. [7] B Cells are the major cells involved in the creation of antibodies that circulate in blood plasma and lymph, known as humoral immunity. Antibodies (also known as ...
The innate immune system is made of non-specific defensive mechanisms against foreign cells inside the host including skin as a physical barrier to entry, activation of the complement cascade to identify foreign bacteria and activate necessary cell responses, and white blood cells that remove foreign substances.