It is here in the aviolar sacs that oxygen is exhanged with the bloodstream for carbon dioxide. Other chemical substances can also enter the bloodstream producing a variety of physiological effects.
There are three basic categories of physiological effects, irritants, aphyxiants, and poisons. Choose the appropriate buttons to explore these effects further.
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Irritants-
Substances which cause a corrosive inflammatory reaction in moist membranes. Especially in the eyes, skin and repiratory tract.
Often pulmonary edema(a filling of the lungs with fluid) can result from exposure to irritants. The aviolar capillaries pour out fluid in an attempt to replace lost moisture.
There are UPPER,LOWER and WHOLE repsiratory irritants. Upper irritants are very water soluble and affect the nose, mouth and throat. Lower irritants affect the far reaches of the lungs and are less water soluble. OFTEN THERE IS NO SIGINIFICANT WARNING PROPERTY OF A CHEMICAL TO AVOID OVEREXPOSURE.
Some examples of irritants-
UPPER- Ammonia, Sulfer Dioxide
LOWER- Nitrogen Dioxide, Acrolein
WHOLE- Chlorine
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Aphyxiants-
Aphyxiation is the primary cause of accidental injury and death in confined space entry. Aphyxiants prevent the body from recieving an adequate supply of oxygen causing Anoxia( a deficiency of oxygen in the tissues).
There are two type of aphyxiants-Simple
and Chemical
Simple aphyxiants produce no direct physiological effect, but at high concentrations simply exclude oxygen
A minimum oxygen concentration in air of 19.5% is desirable for safe confined space entry. Before entering a confined space, it is required to monitor oxygen concentrations with a calibrated and functioning oxygen analyzer to ensure that oxygen is present above 19.5%.
Chemical Aphyxiants can cause anoxia even if sufficient oxygen is present. Carbon monoxide will bind to the bloods hemoglobin about 200 times more readily than oxygen. So at low concentrations of 100 ppm or greater Carbon monoxide can be considered dangerous. It excudes
oxygen by preferential attachment to the blood.
Other chemicals such as aniline or nitrobenzene will cause oxygen to bind tightly to the blood and inhibit its release to the blood stream.
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Systemic Poisons-
Systemic Poisons affect organ tissues and systems within the body. A typical systemic poison may affect one or more of the following systems as an example:
Central Nervous System
Liver
Kidneys
Other systems may also be affected. Central nervous system depressants are substances which impair transmission of nerve impulses. Examples are Isoproyl Alcohol, Acetone, and Carbon disulfide
Hydrocarbons exhibit this tendancy more than other classes of chemicals.
The liver can be considered the detoxification center of the body. Most toxins, heavy metals, organic poisons such as carbon tetrachloride are retained in the liver and can produce chronic damage because the liver has no means of destroying these materials.
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