The respiratory system

Essentially, all primary skin irritants include acids, alkalis, metals, salts, and solvents. Among organic acids one may include acetic acid, acrylic acid, carbolic acid, chloroacetic acid, formic acid, lactic acid, oxalic acid, and salicylic acid. Among inorganic acids one may list arsenious acid, chromic acid, hydrochloric acid, hydrofluoric acid, nitric acid, phosphoric acid, and sulfuric acid. Alkalis include butylamines, ethylamines, ethanolamines, methylamines, propylamines, and triethanolamine. One also may include ammonium carbonate, ammonium hydroxide, calcium carbonate, calcium cyanamide, calcium hydroxide, calcium oxide, potassium carbonate, potassium hydroxide, sodium carbonate (soda ash), sodium hydroxide (caustic soda), and sodium silicate. 

Many metal salts are well-known primary skin irritants. These substances include antimony trioxide, arsenic trioxide, chromium and alkaline chromates, cobalt sulfate, nickel sulfate, mercury chloride, and zinc chloride. In addition to the above industrial chemicals, several solvents are known to act as primary skin irritants among workers, such as, carbon tetrachloride (CCI4), chloroform, ethylene dichloride, epichlorohydrin, ethylene chlorohydrin, perchloroethylene, and trichloroethylene, in addition to cool tar solvents such as naphtha, toluene, and xylene. 

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The use of metered-dose valves in aerosol medical appHcations permits an exact dosage of an active dmg to be deHvered to the respiratory system where it can act locally or be systemicaHy absorbed. For example, inhalers prescribed for asthmatics produce a fine mist that can penetrate into the bronchial tubes (see Antiasthmatic agents). 

Pharmaceutical powder aerosols have more stringent requirements placed upon the formulation regarding moisture, particle size, and the valve. For metered-dose inhalers, the dispensed product must be deflvered as a spray having a relatively small (3—6 -lm) particle size so that the particles can be deposited at the proper site in the respiratory system. On the other hand, topical powders must be formulated to minimize the number of particles in the 3—6-p.m range because of the adverse effects on the body if these materials are accidently inhaled. 

Oxygen inhalators are used as a first-aid measure for a long Hst of emergencies, including heart attacks and suffocation, and as a result are carried routinely by rescue squads. Oxygen—helium mixtures have proved beneficial in asthmatic attacks, because these permit more rapid flow of gas into congested areas of the respiratory system. 

Because a filter sample includes particles both larger and smaller than those retained in the human respiratory system (see Chapter 7, Section III), other types of samplers are used which allow measurement of the size ranges of particles retained in the respiratory system. Some of these are called dichotomous samplers because they allow separate measurement of the respirable and nonrespirable fractions of the total. Size-selective samplers rely on impactors, miniature cyclones, and other means. The United States has selected the size fraction below an aerodynamic diameter of 10 /xm (PMiq) for compliance with the air quality standard for airborne particulate matter. 

B. Removal of Deposited Particles from the Respiratory System... 

The respiratory system has several mechanisms for removing deposited particles (8). The walls of the nasal and tracheobronchial regions are coated with a mucous fluid. Nose blowing, sneezing, coughing, and swallowing... 

Air pollution principally affects the respiratory, circulatory, and olfactory systems. The respiratory system is the principal route of entry for air pollutants, some of which may alter the function of the lungs. 

Hydrofluoric acid is highly corrosive to skin and mucous membranes. Even in fairly low concentrations, it causes painful skin burns and severe damage to eyes and the respiratory system. Exposure at higher levels results in destruction of tissues and death. No one in l e.xas City was exposed to more than trace concentrations of hydrofluoric acid. The acid vessel had a capacity of about 850 barrels of which a small fraction was released. 

Horsfield, K. (1986). Morphometry of airways. In The respiratory system Section 3. Mechanics of Breathing, Part 1vol. Ill (P.T. Macklem and J. Mead, Eds.), pp. 75-88. American Physio logical Society, Bethesda, Maryland. 

The aerodynamic particle diameter determines the fate of particles in the respiratory system. Coarse particles are deposited in the nose and nasopharynx. Smaller particles that pass the upper airway can be deposited in the bronchial region and lower airway. A size-selective deposition model and sampling of particles has been standardized both in Europe and internationally. The... 

Inhaled gaseous compounds are absorbed in all parts of the respiratory system whereas particle size determines how deep into the airways the parti cles will he transported in the airstrearn. Shortness of breath is a typical sign of a chemical exposure that has affected the lungs, and it may be evoked through iminunological mechanisms (e.g., formaldehyde, ethyleneoxide), or through toxic irritation (formaldehyde, isocyanates, sulfur dioxide, nitrogen dioxide, Frequently the mechanism depends on the concentration ol the com... 

Tracheobronchial region The middle region of the respiratory system, comprised of the trachea and the bronchi. 

In connection with their medicinal applications and activities to the respiratory system they showed antiallergic (83EUP80176 85USP4528288), antihistaminic [73BBA(304)693 85GEP(0)3427823 86EUP181282 ... 

Particles are present in outdoor air and are also generated indoors from a large number of sources including tobacco smoking and other combustion processes. Particle size, generally expressed in microns (10-6 m) is important because it influences the location where particles deposit in the respiratory system (U.S. Environmental Protection Agency 1995), the efficiency of particle removal by air filters, and the rate of particle removal from indoor air by deposition on surfaces. 

The oxides of nitrogen are somewhat sol in w, reacting with it in the presence of oxygen to form nitric and nitrous acids. This is the action that takes place deep in the respiratory system. The acids formed are irritants, causing congestion of the throat and bronchi, and edema of the lungs. The acids are neutralized by the alkalies present in the tissues, with the formation of nitrates and nitrites. The latter may cause some arterial dilation, fall in blood press, headache and dizziness, and there may be some formation of methemoglobin. However, the nitrite effect is of secondary importance... 

When kaolin or aluminum is administered widi die lincosamides, die absorption of the lincosamide is decreased. When the lincosamides are administered with the neuromuscular blocking drag (drag diat are used as adjuncts to anesthetic drag diat cause paralysis of the respiratory system) die action of die neuromuscular blocking drug is enhanced, possibly leading to severe and profound respiratory depression. 

Herpes zoster (shingles) is caused by the varicella (chickenpox) virus. It is highly contagious. The virus causes chickenpox in the child and is easily spread via the respiratory system. Recovery from childhood chickenpox results in the infection lying dormant in the nerve cells. The virus may become reactivated later in life as the older adult s immune system... 

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