Tissue damage, pathogens

Another reason for complexity of cell-activation mechanisms resides in the end response of neutrophils - that is, the delivery of cytotoxic products. Whilst these products are highly lethal towards pathogens, they can also attack and destroy host tissues, and this can have deleterious effects on tissue function. Complex intracellular signalling mechanisms to activate these cytotoxic pathways also guards against non-specific activation, which could lead to host tissue damage. 

Inflammation is a local and early response of a tissue to a noxious stimulus, such as physical injury or infection. It results in an increase in the number of immune cells in the area of damage or infection which kill pathogens, remove damaged or dead cells and initiate the healing process. The well-known characteristics of inflammation are redness, heat, swelling and pain. Redness is due to increased blood flow to the damaged area caused by vasodilation of small arterioles, which facilitates an increase in the number of immune cells in the damaged area and facilitates provision... 

Whereas the normally functioning immune response can successfully neutralize toxins, inactivate viruses, destroy transformed cells, and eliminate pathogens, inappropriate responses can lead to extensive tissue damage (hypersensitivity) or reactivity against self antigens (autoimmunity) conversely, impaired reactivity to appropriate targets (immunodeficiency) may occur and abrogate essential defense mechanisms. 

Exposure through breaks in the skin can result in the introduction of both toxins and pathogens. Toxins or toxic particles that are soluble in the blood plasma can be absorbed into the blood quite rapidly. For example, dermal exposure to chromic acid used in the electroplating industry can cause tissue damage, which then allows rapid uptake of hexavalent chromium ion and potential acute chromium intoxication. 

More expensive and costly to produce Potential for infection at site of injection Potential for sepsis Potential for thrombophlebitis Potential for fluid overload Potential for air embolism Potential for extravasation Psychological distress by the patient Require specialized equipment, devices, and techniques to prepare and administer drugs Potential for pain upon injection Potential for tissue damage upon injection Risk of needlestick injuries and exposure to blood-borne pathogens by health care worker Increased morbidity associated with long-term vascular access devices Disposal of needles, syringes, and other infusion devices requires special consideration... 

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