Lecture
Toxic substances that have entered the blood are carried by it throughout the
body. The volume of circulating blood and the content of the poison in each organ
depend on its blood supply. Through the heart, lungs, brain, and liver
flows considerably more blood, and hence more medicinal substances and poisons contained in
it, than through other organs.
Toxic substances pass from the blood capillaries into the intercellular space, and then penetrate into cells through the membranes.
Most toxic substances are distributed unevenly among different organs and tissues. The distribution of substances in the body depends on their physical
and chemical properties (solubility in water, fats and other lipids, dissociation), the composition and functional characteristics of organs and tissues: Substances
well soluble in lipids (anesthetics, hypnotics, sedatives, chlorine-containing organic insecticides, etc.) readily penetrate
biological membranes, and are rapidly and selectively distributed to organs and tissues rich in
lipids and well supplied with blood (predominantly in the brain and bone marrow).
Barbiturates, especially short-acting thiobarbiturates (sodium
thiopental), first enter the brain, and then pass into the
plasma, from which they enter organs and tissues rich in lipids.
Predominantly fat-soluble poisons are deposited in adipose tissue.
(organic solvents, chlorine derivatives of hydrocarbons, etc.). Plumbum, barium, and fluorine, etc., are deposited in bone
tissue. Tetracycline-group
antibiotics are related to dental and bone tissue, in which they accumulate after entering the body. Aminazine (chlorpromazine) is localized predominantly in the brain, while benzene is localized in the bone marrow. In the skin
aurum and argentum are deposited. Elements such as bismuth, mercury, and arsenic accumulate in organs and tissues rich in proteins containing
sulfhydryl or other reactive functional groups. Mercury accumulates in the kidneys, causing necrotic changes in them.
Calcium ions and those of certain other metals bind with glycosaminoglycans (mucopolysaccharides) and mucoproteins contained in the intercellular fluid. In acute poisoning, mercury and arsenic are localized in the liver
and kidneys, while in chronic poisonings these elements can be deposited in the
nails, bones, and nervous tissue. In chronic arsenic poisoning, it
can also be detected in the hair.
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