Protection against foreign bodies

Fig. 25 Protection against foreign bodies by a combination of metal detectors and magnetic drum separator...

The cornea serves as a protective layer of the eye and is comprised of several layers. The epithelium is the initial layer (0.1 mm). The multicellular epithelium consists of 56 layers of cells, and these layers pose a barrier to drug penetration. The tight jimctions prevent movement of drugs from the lacrimal fluid into the eye, while the stromal layer, because of its hydrated nature, hinders the movement of lipophilic drugs. These defense mechanisms of the eye protect it against foreign bodies, and consequently they affect drug... 

No protection of equipment against ingress of solid foreign bodies. 

Protection against ingress of large solid foreign bodies (diameter greater than 50 mrn). 

Biological systems possess a number of mechanisms for protection against toxic foreign compounds, some of which have already been mentioned. Thus, metabolic transformation to more polar metabolites, which are readily excreted, is one method of detoxication. For example, conjugation of paracetamol with glucuronic acid and sulfate facilitates elimination of the drug from the body and diverts the compound away from potentially toxic pathways (see chap. 7). Alternatively, a reactive metabolite may be converted into a stable metabolite. For example, reactive epoxides can be metabolized by epoxide hydrolase to stable dihydrodiols. 

Protective These proteins that protect the body. Some form part of the bodies immune system defending the body against foreign molecules and bacteria. Others, such as the blood clotting agents thrombin and fibrinogen, prevent loss of blood when a blood vessel is damaged. 

A certain problem of electrical installations with a high degree of ingress protection against solid foreign bodies and water is the exchange of internal... 

The hallmark of the immune system is its ability to respond to an invasion of the body by microorganisms or toxic components in ways that afford protection against the detrimental effects that could occur. The responses of the immune system include both specific (adaptive immune system) and non-specific (innate immune system) components. These react in different ways to antigens, which are substances foreign to the host. For example, antigens can be protein or polysaccharide components of microorganisms, but also toxic substances produced by them. Components of innate and adaptive immunity are listed in Table 4.1. 

Antibodies are proteins made in the body in response to foreign substances such as bacteria or viruses. Interferon is an important antibody because it offers general protection against viruses (many antibodies target specific invaders). 

EN 60529 outlines an international classification for the sealing effectiveness of enclosures of electrical equipment against the intrusion into the equipment of foreign bodies (i.e., dust, tools, fingers) and moisture. This classification system utilizes the letters IP (Ingress Protection) followed by two digits. An X is used for one of the digits if there is only one class of protection i.e. IP X4 which addresses moisture resistance only. 

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