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Chapter 16: The Respiratory System

The Respiratory System . The respiratory system, when viewed from a toxicological perspective, is important in that itProvides an early warning detection system via olfaction for many airborne toxicantsProvides an exposure pathway for systemic exposures to many toxicantsIs a direct target of toxi

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Chapter 16: The Respiratory System

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    1. Chapter 16: The Respiratory System

    2. The Respiratory System The respiratory system, when viewed from a toxicological perspective, is important in that it Provides an early warning detection system via olfaction for many airborne toxicants Provides an exposure pathway for systemic exposures to many toxicants Is a direct target of toxicity from exposures to many airborne chemicals and from some that have been orally consumed Is an important organ system for many xenobiotic biotransformations

    3. The Respiratory System, cont. The respiratory system is subjected to frequent assault by airborne environmental contaminants. The average adult inhales approximately 12 kg of air daily, although this value may increase dramatically with physical activity or exertion. Compared with average daily food (1.5 kg) or water (2 kg) intake, it is obvious that inhaled air is a major source of potential exposures to environmental toxicants.

    4. The Respiratory System, cont. At times, the concentration of airborne chemical contaminants increases to levels immediately dangerous to life and health: The accidental release of 40 tons of methyl isocyanate in Bhopal, India in 1984 A short-term inversion of smoke and sulfur dioxide in London, England in 1952 resulted in thousands of deaths, principally among the sick and elderly.

    5. The Respiratory System, cont. These episodes illustrate the danger that concentrated air pollution may pose. They also offer additional insight into the potential hazards posed by lower concentration chronic exposures and their role in the pathogenesis and exacerbation of respiratory disorders like chronic bronchitis and bronchial asthma.

    6. The Respiratory System The respiratory system is responsible for: maintenance of life through gas exchange many nonrespiratory functions like: immune system maintenance Metabolism of endogenous substances like angiotensin Metabolism of environmental pollutant

    7. The Respiratory System, cont. The respiratory system plays an important role in: Recognition of xenobiotics Metabolism of xenobiotics Detoxification of xenobiotics elimination of xenobiotics The surface epithelium of the respiratory system is an interface exposed to external contaminants via inhaled breath.

    8. The Respiratory System Inhaled air contains: A variety of nonessential gases Vapors Aerosols Particulates All of these may possess the capacity to induce local injury or systemic injury. The respiratory system can provide a route for systemic toxicants in addition to those that target the system directly. For example, nitrogen dioxide can cause pulmonary fibrosis upon inhalation without producing systemic toxicity.

    9. Systemic Toxicities Through Respiratory Exposure

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