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The second and third lines of defense operate by making changes to the buffers, each of which consists of two components: a weak acid and its conjugate base. [5] [13] It is the ratio concentration of the weak acid to its conjugate base that determines the pH of the solution. [14]
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.
Complement proteins are proteins that play a role in the non-specific immune responses alongside these non-specific immune cells to make up the first line of immune defense. [4] The non-specific immune response is an immediate antigen-independent response, however it is not antigen-specific. Non-specific immunity results in no immunologic memory.
A scanning electron microscope image of a single neutrophil (yellow/right), engulfing anthrax bacteria (orange/left) – scale bar is 5 μm (false color). The immune system is a network of biological systems that protects an organism from diseases.
The innate immune system is an alternate defense strategy and is the dominant immune system response found in plants, fungi, prokaryotes, and invertebrates (see Beyond vertebrates). [ 2 ] The major functions of the innate immune system are to:
In the first line of defense, inhaled bacteria are trapped by mucus and are swept toward the pharynx and are swallowed. [1] Bacteria which penetrate the mucous layer are dealt with a second line of defense which includes antimicrobial peptides that are secreted by the surface epithelium of the respiratory tract which kill many strains of ...
The mononuclear phagocyte system is part of both humoral and cell-mediated immunity. The mononuclear phagocyte system has an important role in defense against microorganisms, including mycobacteria, fungi, bacteria, protozoa, and viruses. Macrophages remove senescent erythrocytes, leukocytes, and megakaryocytes by phagocytosis and digestion.
The glia limitans also acts as a second line of defense against anything that passes the blood–brain barrier. However, because the astrocytes surrounding the vessels are connected by gap junctions, it is not considered part of the BBB and material can readily pass between the foot processes.