专业术语—口腔生理学术语P4(英文详解)（在线收听）

    Polymers-large molecules made up of many joined units of a more simple molecule. Examples are polysaccharides and polypeptides.

    Polypeptides; -chains of amino acids joined by peptide bonds. They are not the size of proteins, but may be biologically very active. Some hormones are peptides, such as insulin which has 51 amino-acid residues. Peptides may also be powerful neurotransmitter substances.

    Polyphyodont - continuous replacement of teeth with many generations (from "poly" =many; "phylo" = generation and "dont" =teeth). See also diphyodont

    Polysaccharides - long molecules made of chains of sugars linked together. Examples are starch, glycogen and dextrans.

    Predentine - the extracellular matrix produced by odontoblasts, which becomes mineralised to form dentine. Similar in structure to osteoid.

    Procaryote - a cell in which the genetic material is dispersed throughout the cell in distinction to a eucaryote which has a nucleus and other organelles. Bacteria and blue-green algae are procaryotes

    Prognathic- a prominent lower jaw which may bring the lower teeth ahead of the upper teeth

    Proline- one of 20 amino acids common in proteins. It is a common amino acid of collagen and like lycine must be hydroxylated by ascorbic acid in order to allow the formation of hydrogen bonds which will hold the triple helix together.

    Proline-rich proteins - a group of proteins in saliva which have the ability to bind to calcium. They provide the protective layer of pellicle on the tooth surfaces by binding to the calcium in enamel. They also bind onto microorganism, providing a link between organism and the tooth surface. Proline rich proteins help to de-toxify tanins, which are potentially poisonous plant substances found in tea, and unripe fruit.