A naturally occurring chemical that performs a wide range of biological roles. It is involved in the laying down of memories in the BRAIN; in killing viruses, bacteria and cancer cells; and in helping to control blood pressure. NO, comprising a nitrogen atom attached to an oxygen one, is one of the smallest of biologically active compounds as well as having such diverse functions. The chemical is a muscle relaxant and is important in maintaining the heart and circulation in good condition. NO is also the toxic agent released by macrophages (see MACROPHAGE) to kill invading germs and spreading cancer cells. It acts as an essential NEUROTRANSMITTER and protects nerve cells against stress. Researchers are studying how it might be used to treat diseases, for example by using it as an inhaled gas in certain respiratory conditions.
An ingredient of many skin preparations that has a mild astringent action and a soothing effect. Zinc oxide is used to treat painful, itchy, or moist skin conditions and to ease the pain caused by haemorrhoids and insect bites or stings. It also blocks the ultraviolet rays of the sun (see sunscreens).... zinc oxide
Also known as laughing gas, this is (at ordinary pressures) a colourless, sweetish-smelling gas. It is used with oxygen to provide relief of pain (see ANALGESICS; PAIN) and mild ANAESTHESIA during childbirth, during painful dental procedures, and at the site of major accidents. It has a rapid action and the effects do not last for long.... nitrous oxide gas
a strong corrosive mineral acid, HNO3, the concentrated form of which is capable of producing severe burns of the skin. Swallowing the acid leads to intense burning pain and ulceration of the mouth and throat. Treatment is by immediate administration of alkaline solutions, followed by milk or olive oil.... nitric acid
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