Immune system

The immune system is the network of biological processes that protects an organism from diseases. It detects as well as responds to a wide species of pathogens, from viruses to parasitic worms, as alive as cancer cells & objects such(a) as wood splinters, distinguishing them from the organism's own healthy tissue. numerous species work two major subsystems of the immune system. The innate immune system allowed a preconfigured response to broad groups of situations and stimuli. The adaptive immune system enable a tailored response to used to refer to every one of two or more people or things stimulus by learning to recognize molecules it has before encountered. Both ownership molecules and cells to perform their functions.

Nearly any organisms draw some kind of immune system. Bacteria have a rudimentary immune system in the form of enzymes that protect against virus infections. Other basic immune mechanisms evolved in ancient plants and animals and carry on in their innovative descendants. These mechanisms add phagocytosis, antimicrobial peptides called defensins, and the complement system. Jawed vertebrates, including humans, have even more modern defense mechanisms, including the ability to adapt to recognize pathogens more efficiently. Adaptive or acquired immunity creates an immunological memory leading to an enhanced response to subsequent encounters with that same pathogen. This process of acquired immunity is the basis of vaccination.

Dysfunction of the immune system can cause Hashimoto's thyroiditis, rheumatoid arthritis, diabetes mellitus type 1, and systemic lupus erythematosus. Immunology covers the explore of all aspects of the immune system.

Surface barriers

Several barriers protect organisms from infection, including mechanical, chemical, and biological barriers. The waxy cuticle of nearly leaves, the exoskeleton of insects, the shells and membranes of externally deposited eggs, and skin are examples of mechanical barriers that are the number one line of defense against infection. Organisms cannot be totally sealed from their environments, so systems act to protect body openings such as the lungs, intestines, and the genitourinary tract. In the lungs, coughing and sneezing mechanically eject pathogens and other irritants from the respiratory tract. The flushing action of tears and urine also mechanically expels pathogens, while mucus secreted by the respiratory and gastrointestinal tract serves to trap and entangle microorganisms.

Chemical barriers also protect against infection. The skin and respiratory tract secrete antimicrobial peptides such as the β-defensins. Enzymes such as lysozyme and phospholipase A2 in saliva, tears, and breast milk are also antibacterials. Vaginal secretions serve as a chemical barrier coming after or as a result of. menarche, when they become slightly acidic, while semen contains defensins and zinc to kill pathogens. In the stomach, gastric acid serves as a chemical defense against ingested pathogens.

Within the genitourinary and gastrointestinal tracts, commensal flora serve as biological barriers by competing with pathogenic bacteria for food and space and, in some cases, changing the conditions in their environment, such as pH or available iron. As a result, the probability that pathogens willsufficient numbers to cause illness is reduced.