Poison

From ArticleWorld

A poison is an organic or inorganic substance that causes injury, illness or perhaps death in an individual or organism that comes in contact with it. Poisoning can occur as a result of inhalation, ingestion, injection or absorption through the skin. Poisons that are injected subcutaneously by another organism are generally called venoms. Poisons often work by obstructing or inhibiting a biochemical reaction inside the body.

Basic Types

Scientists refer to some poisons as capable of causing acute poisoning which occurs very rapidly. Some neurotoxins paralyze an individual, including the muscles involved in breathing, resulting in death in seconds. High doses of injected potassium chloride will block cardiac muscle contraction and stops the heart almost immediately. Cyanide gas or ingestion blocks the functioning of the mitochondrial cellular respiration, leading to an immediate loss of cellular energy and death.

Other poisons cause chronic poisoning. Substances like mercury and lead cause poisoning by gradually accumulating in the body tissues causing tissue damage and cellular death. Symptoms emerge slowly and the individual doesn’t always recognize that they are being poisoned until the proper tests are done that prove the existence of toxic amounts of these metallic substances.

Mechanisms

Some poisons are toxic by themselves when taken into the body. Others need to be metabolized by the liver into a toxic metabolite which is actually the real poison. For example, methanol or “wood alcohol” is metabolized by the liver into formaldehyde which is poisonous.

Other toxic poisons affect the neurological system by attacking nerve cells and causing paralysis. Poisons that attack the heart include digoxin and digitoxin that can slow the heart or cause abnormal heart arrhythmias. Some poisons are directly caustic and destructive to tissues. Strong acids and bases will burn or dissolve tissue upon contact, leading to mucus membrane or skin damage.

Gases and vapors are dangerous to skin or when inhaled. Carbon monoxide is a poison that, when inhaled, replaces oxygen in the red blood cells leaving no room for oxygen so that the individual “suffocates” from lack of oxygen. Formaldehyde, phosgene and phosphine are gaseous vapors that attack the body when inhaled through the lungs.

Some pesticides cause poisoning by virtue of disrupting the citric acid cycle, disrupting electron transport in the cells or by being carcinogens. Many poisons are toxins that are derived from certain kinds of shellfish or from other kinds of food. Botulism is a poisoning caused by the botulinum toxin that is found in poorly processed foods.