![]() ![]() increased production of mucus, which can cause symptoms like a runny nose or a productive cough.swelling of affected tissues, such as the upper throat during the common cold or joints affected by rheumatoid arthritis.heat, either increased local temperature, such as a warm feeling around a localized infection, or a systemic fever.redness of the skin, due to locally increased blood circulation.The inflammatory response is characterized by the following symptoms: These cytokines include TNF, HMGB1, and IL-1. Cytokines produced by macrophages and other cells of the innate immune system mediate the inflammatory response. Neutrophils then trigger other parts of the immune system by releasing factors that summon additional leukocytes and lymphocytes. These cell death pathways help clear infected or aberrant cells and release cellular contents and inflammatory mediators.Ĭhemical factors produced during inflammation ( histamine, bradykinin, serotonin, leukotrienes, and prostaglandins) sensitize pain receptors, cause local vasodilation of the blood vessels, and attract phagocytes, especially neutrophils. PRR activation and its cellular consequences have been well-characterized as methods of inflammatory cell death, which include pyroptosis, necroptosis, and PANoptosis. At the onset of an infection, burn, or other injuries, these cells undergo activation (one of their PRRs recognizes a PAMP) and release inflammatory mediators, like cytokines and chemokines, which are responsible for the clinical signs of inflammation. These cells present receptors contained on the surface or within the cell, named pattern recognition receptors (PRRs), which recognize molecules that are broadly shared by pathogens but distinguishable from host molecules, collectively referred to as pathogen-associated molecular patterns (PAMPs). The process of acute inflammation is initiated by cells already present in all tissues, mainly resident macrophages, dendritic cells, histiocytes, Kupffer cells, and mast cells. It establishes a physical barrier against the spread of infection and promotes healing of any damaged tissue following pathogen clearance. Inflammation is stimulated by chemical factors released by injured cells. Inflammation is one of the first responses of the immune system to infection or irritation. P-glycoprotein (mechanism by which active transportation is mediated) Mucociliary escalator, surfactant, defensins Įndothelial cells (via passive diffusion/ osmosis & active selection). Peristalsis, gastric acid, bile acids, digestive enzyme,įlushing, thiocyanate, defensins, gut flora Sweat, desquamation, flushing, organic acids skin flora The flushing action of tears and saliva helps prevent infection of the eyes and mouth. Gut flora can prevent the colonization of pathogenic bacteria by secreting toxic substances or by competing with pathogenic bacteria for nutrients or cell surface attachment sites. In the gastrointestinal and respiratory tract, movement due to peristalsis or cilia, respectively, helps remove infectious agents. Lack of blood vessels, the inability of the epidermis to retain moisture, and the presence of sebaceous glands in the dermis, produces an environment unsuitable for the survival of microbes. Desquamation (shedding) of skin epithelium also helps remove bacteria and other infectious agents that have adhered to the epithelial surface. The epithelial surfaces form a physical barrier that is impermeable to most infectious agents, acting as the first line of defense against invading organisms. act as a physical and chemical barrier to infectious agents via physical measures such as skin and chemical measures such as clotting factors in blood, which are released following a contusion or other injury that breaks through the first-line physical barrier (not to be confused with a second-line physical or chemical barrier, such as the blood–brain barrier, which protects the nervous system from pathogens that have already gained access to the host).Īnatomical barriers include physical, chemical and biological barriers.activate the adaptive immune system through antigen presentation.identify and remove foreign substances present in organs, tissues, blood and lymph, by specialized white blood cells.activate the complement cascade to identify bacteria, activate cells, and promote clearance of antibody complexes or dead cells. ![]()
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