Water physiological action

In 1868 two Scottish scientists, Crum Brown and Fraser [4] recognized that a relation exists between the physiological action of a substance and its chemical composition and constitution. That recognition was in effect the birth of the science that has come to be known as quantitative structure-activity relationship (QSAR) studies a QSAR is a mathematical equation that relates a biological or other property to structural and/or physicochemical properties of a series of (usually) related compounds. Shortly afterwards, Richardson [5] showed that the narcotic effect of primary aliphatic alcohols varied with their molecular weight, and in 1893 Richet [6] observed that the toxicities of a variety of simple polar chemicals such as alcohols, ethers, and ketones were inversely correlated with their aqueous solubilities. Probably the best known of the very early work in the field was that of Overton [7] and Meyer [8], who found that the narcotic effect of simple chemicals increased with their oil-water partition coefficient and postulated that this reflected the partitioning of a chemical between the aqueous exobiophase and a lipophilic receptor. This, as it turned out, was most prescient, for about 70% of published QSARs contain a term relating to partition coefficient [9]. 

Physiological action Produces casualties when inhaled or absorbed Required level of protection Protective mask and clothing Decontamination STB slurry or DS2 solution hot soapy water M258A1, M280... 

Heller VG, Pursell L. 1938. Phenol-contaminated waters and their physiological action. J Pharmacol ExpTher 63 99-107. 

Action of Water on Metals and Metallic Compounds—Decomposition by Radioactive Substances and Ultra-violet Light- Water ns a Catalyst -Inllueiiee of Desiccation upon the Properties of Substances—Physiological Action. 

In their physiological action atropine and hyoscyamine are similar and exert what is termed a mydriatic action causing dilation of the pupil of the eye. This action may be produced eithef by external application or by taking internally. As little as i part atropine in 130,000 parts of water will exert a distinct action on the eye. They decrease body secretions and also affect the heart. Taken internally they are poisonous in as little as o.i gm. Tropine exerts no mydriatic action when applied to the eye but in large doses internally it does produce dilation. In addition to the use of these alkaloids in the pure form, extracts of belladonna are also used. 

Steroid hormones (e.g., cortisol and estrogen) are hydro-phobic and insoluble in water. These hormones circulate in plasma, reversibly bound to transport proteins (e.g., cortisol-binding globulin and sex-hormone binding globulin) with only a small fraction free or unbound available to exert physiological action.The half-life of steroid hormones is 30 to 90 minutes. Free steroid hormones, being hydrophobic, enter the cell by passive diffusion and bind with intracellular receptors either in the cytoplasm or the nucleus. ... 

VIP has a large number of ill-defined physiological actions, some of which are shared with other similar polypeptide hormones (secretin and GIF). It acts as a neurotransmitter in the central and autonomic nervous systems and causes vasodilation and relaxation of the smooth muscles of the circulatory and genitourinary systems and the gut. Other actions of VIP include an increase of water and electrolyte secretion from the pancreas and gut release of hormones from the pancreas, gut, and hypothalamus stimulation of lipolysis, glycolysis, and bile flow and inhibition of gastrin and gastric acid secretion. Most of the actions of VIP tend to be of short duration because of its rapid degradation. 

Comparison of SL between two varieties of alfalfa seed in distilled water and NaCI. The physiological action of the salt stressed germinating alfalfa seeds was restricted to some extent. SL of alfalfa seeds in NaCI was lower than in distilled water. In NaCI, the SL value of the seed decreased markedly, and the characteristic SL peak appeared 24 h later than for others treatments (Fig. 2). 

Mustard gas is a liquid which boils at 216°, freezes at 14°, and slowly hydrolyzes when in contact with water. It is the most toxic of the gases used in the war, and in addition is highly vesicant, as it produces painful burns at a high dilution. Its physiological action is thought to be due to the fact that it readily penetrates the cell-walls and then, as the result of hydrolysis, hydrochloric acid is formed. Its action is relatively slow and, as a consequence, the vapor can be breathed for some time without any apparent effect it is for this reason a source of great danger. 

Physiological action— The fat-soluble vitamins are required for the regulation of the metabolism of structural units, and each vitamin appears to have one or more specific roles. Collectively, the water-soluble B vitamins are primarily concerned with the transfer of energy. 

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