（单词翻译:单击）
Prostaglandins - are members of a class of hormones1 known as the eicosanoids. They are released by cells which have been damaged and have a powerful ability to sensitise nerve endings causing tenderness to the damaged area, and to cause vasoconstriction by contracting the smooth muscle of arterioles. They belong to a group of compounds which have a similar effect on nervous tissue, known asneuropeptides.
Proteins - usually very large molecules2, from 10,000 to 200,000 amino acids, which form the structural3 component4 of a cell'smatrix. and cytoskeleton. All enzymes5 are proteins.
Proton - the positively6 charged elements of the nucleus7 of an atom. A hydrogen atom without its electron amounts to a single proton charge.
Pulp8 - the dental pulp is a connective tissue trapped inside the fully9 formed tooth with just one entry and exit for nerves and vessels10, at the apex11 of the root. The characteristic cell of the pulp, is the odontoblast, which lines the walls of the pulp chamber12 and is able to form dentine throughout life.
Pulpitis - inflammation of the dental pulp caused by irritation13 from chemical, physical or bacterial14 injury, usually transmitted to the pulp via the dentine. It is important for the clinical management of the tooth, to decide whether the pulpitis is reversible, that is will it resolve if the irritation is removed, or whether it has been damaged beyond its capacity to repair.
Pyrophosphate - inhibitors of mineralisation, they may offer up phospate ions in the presence of alkaline phosphatase. Crystals of calcium15 pyrophosphates are found in abnormal calcification16 of soft tissue, such as the disc of the TM Joint17.
