Poisons That Can Be Absorbed Through the Skin
poison, in biochemistry, a substance, natural or synthetic, that causes impairment to living tissues and has an injurious or fatal event on the trunk, whether it is ingested, inhaled, or captivated or injected through the skin.
Although poisons have been the subject area of practical lore since ancient times, their systematic study is often considered to accept begun during the 16th century, when the German-Swiss physician and alchemist Paracelsus first stressed the chemical nature of poisons. It was Paracelsus who introduced the concept of dose and studied the actions of poisons through experimentation. It was non until the 19th century, still, that the Spaniard Matthieu Orfila, the attending doc to Louis Xviii, correlated the chemical science of a toxin with the biological furnishings it produces in a poisoned individual. Both concepts continue to be key to an understanding of modernistic toxicology.
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Poisoning involves 4 elements: the poison, the poisoned organism, the injury to the cells, and the symptoms and signs or death. These four elements stand for the crusade, subject, consequence, and event of poisoning. To initiate the poisoning, the organism is exposed to the toxic chemical. When a toxic level of the chemical is accumulated in the cells of the target tissue or organ, the resultant injury to the cells disrupts their normal structure or role. Symptoms and toxic signs then develop, and, if the toxicity is severe enough, death may result.
This article considers humans every bit the primary subjects of poisoning. It kickoff discusses the actions of poisons on the body and then examines primary types of synthetic and natural poisons.
Nature of a toxic substance
Definition of a poison
A poison is a substance capable of producing agin effects on an individual nether appropriate conditions. The term "substance" is nigh always synonymous with "chemical" and includes drugs, vitamins, pesticides, pollutants, and proteins. Fifty-fifty radiation is a toxic substance. Though not usually considered to be a "chemical," most radiations are generated from radioisotopes, which are chemicals. The term "adverse furnishings" to a higher place refers to the injury, such as structural harm to tissues. "Appropriate conditions" refers to the dosage of the substance that is sufficient to cause these adverse effects. The dose concept is of import considering co-ordinate to information technology even a substance equally innocuous as h2o is poisonous if also much is ingested. Whether a drug acts as a therapy or every bit a poison depends on the dose.
Nomenclature of a poison
Poisons are of such diverse natures that they are classified by origin, concrete grade, chemic nature, chemical activity, target site, or use.
Classification based on origin
Poisons are of microbial, plant, animal, or synthetic origin. Microbial poisons are produced by microscopic organisms such as bacteria and fungi. Botulinus toxin, for example, is produced past the bacterium Clostridium botulinum and is capable of inducing weakness and paralysis when present in underprocessed, nonacidic canned foods or in other foods containing the spores. An example of a plant toxin is the belladonna alkaloid hyoscyamine, which is constitute in belladonna (Atropa belladonna) and jimsonweed (Datura stramonium).
Animal poisons are usually transferred through the bites and stings of venomous terrestrial or marine animals, the onetime group including poisonous snakes, scorpions, spiders, and ants, and the latter grouping including body of water snakes, stingrays, and jellyfish. Synthetic toxins are responsible for most poisonings. "Synthetic" refers to chemicals manufactured by chemists, such as drugs and pesticides, also as chemicals purified from natural sources, such as metals from ores and solvents from petroleum. Constructed toxins include pesticides, household cleaners, cosmetics, pharmaceuticals, and hydrocarbons.
Classification based on physical class
The physical grade of a chemical—solid, liquid, gas, vapour, or droplets—influences the exposure and absorbability.
Considering solids are generally non well absorbed into the blood, they must be dissolved in the aqueous liquid lining the intestinal tract if ingested or the respiratory tract if inhaled. Solids dissolve at unlike rates in fluids, however. For example, compared with lead sulphate granules, granules of pb are practically nontoxic when ingested, because elemental lead is substantially insoluble in water, while lead sulphate is slightly soluble and absorbable. Even different-sized granules of the same chemical tin vary in their relative toxicities considering of the differences in dissolution rates. For case, arsenic trioxide is more toxic in the course of smaller granules than is the same mass of larger granules because the smaller granules dissolve faster.
A poison in a liquid form tin be absorbed by ingestion or by inhalation or through the skin. Poisons that are gases at room temperature (e.chiliad., carbon monoxide) are absorbed mainly by inhalation, as are vapours, which are the gas phase of substances that are liquids at room temperature and atmospheric pressure level (e.1000., benzene). Because organic liquids are more volatile than inorganic liquids, inhalation of organic vapours is more mutual. Although vapours are generally absorbed in the lungs, some vapours that are highly soluble in lipids (due east.g., furfural) are also absorbed through the skin.
Aerosols are solid or liquid particles small plenty to remain suspended in air for a few minutes. Fibres and dust are solid aerosols. Aerosol exposures occur when aerosols are deposited on the peel or inhaled. Aerosol toxicity is usually college in the lungs than on the skin. An example of a toxic fibre is asbestos, which tin can crusade a rare form of lung cancer (mesothelioma).
Many liquid poisons can exist as liquid aerosols, although highly volatile liquids, such as benzene, seldom be as aerosols. A moderately volatile liquid poison can be equally both an aerosol and as a vapour. Airborne liquid chemicals of depression volatility exist only as aerosols.
Classification based on chemic nature
Poisons tin be classified according to whether the chemical is metal versus nonmetallic, organic versus inorganic, or acidic versus alkali metal. Metal poisons are oft eliminated from the trunk slowly and accumulate to a greater extent than nonmetallic poisons and thus are more likely to cause toxicity during chronic exposure. Organic chemicals are more soluble in lipids and therefore can usually pass through the lipid-rich cell membranes more readily than can inorganic chemicals. Every bit a result, organic chemicals are more often than not absorbed more extensively than inorganic chemicals. Nomenclature based on acidity is useful because, while both acids and alkalis are corrosive to the eyes, skin, and intestinal tract, alkalis generally penetrate the tissue more than deeply than acids and tend to cause more than severe tissue impairment.
Classification based on chemic activity
Electrophilic (electron-loving) chemicals attack the nucleophilic (nucleus-loving) sites of the cells' macromolecules, such every bit deoxyribonucleic acid (Dna), producing mutations, cancers, and malformations. Poisons too may be grouped co-ordinate to their ability to mimic the structure of certain of import molecules in the cell. They substitute for the cells' molecules in chemical reactions, disrupting important cellular functions. Methotrexate, for example, disrupts the synthesis of DNA and ribonucleic acid (RNA).
Other classifications
Unlike the classifications described to a higher place, at that place is usually no predictive value in classification past target sites or by uses. Such classifications are done, however, to systematically categorize the numerous known poisons. Target sites include the nervous system, the cardiovascular organization, the reproductive organization, the immune system, and the lungs, liver, and kidneys. Poisons are classified past such uses as pesticides, household products, pharmaceuticals, organic solvents, drugs of abuse, or industrial chemicals.
Source: https://www.britannica.com/science/poison-biochemistry
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