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Code - the code of nucleotides is written in "words" of three letters using an"alphabet" of four "letters". These four components of the code are adenine, thymine, cytosine, and guanine.
Collagen - the most common protein found in the body. It has a fibrous structure and makes up the main organic component of bone and dentine, and the fibres of tendons and ligaments.
Collagenase - an enzyme produced by fibroblasts which breaks down collagen fibres. The fibroblast recycles the component amino acids, and secretes5 new collagen fibres. This process of remodelling occurs throughout life. Osteoclasts also secrete4 collagenases in order to remove bone matrix. Several bacteria are able to secrete collagenases and are thus able to break down and penetrate7 through collagen fibres in the periodontal ligament.
Colonies - communities of organisms which have taken up residence in a habitat .
Competency - the ability of a cell to respond to messengers which could cause it to differentiate8 into a more specialised cell. Some cells, like pericytes remain competent throughout life, whereas others, such as the oral epithelium, are only able to form an tooth bud during the 12th to 16th week of foetal development.
Composite - a material made from two or more different types of material which contribute different properties. For example bone is a combination of a resilient fibres of collagen in a brittle9 matrix (hydroxyapatite).
Compressive strength - ability to withstand a crushing force.
Condylar process - the vertical extension of the mandible which ends in the condyle head, the moveable part of the temporomandibular joint.
Connective tissue - one of the four main types of collections of cells (tissues) which consists of cells in a matrix of ground substance and fibres. Some connective tissues support structures like blood vessels and glands. Others are more structural, like bone, tendons and cartilage.
Contralateral - the opposite side as distinct from ipsilateral. Often used to refer to the teeth, joint or muscles on the opposite side from the chewing side.
Coronoid process - the vertical extension of the mandible anterior to the condyle to which the temporal muscle attaches.
Cortical-bone - the outer layer of bone which is dense16 and made up of lamellae.
Covalent bond - a strong bond between atoms formed by sharing outer electrons. When an atom has 8 outer electrons it is stable. Those which naturally have 8, like neon and argon gasses are quite unreactive. The carbon atom has 4 outer electrons and therefore needs 4 extra electrons to be stable. Four hydrogen atoms make a good partnership1 for carbon,(CH4, C2 H6 ... etc) hence hydrocarbons,(saturated with hydrogen atoms) are quite stable, insoluble and unreactive. One oxygen atom (outer shell has 6 electrons) and two hydrogen atoms (H2O) also makes a stable arrangement, although not as stable as the hydrocarbon, family as the water molecule is a little unbalanced, providing hydrogen bonds and other unusual properties of biological importance, such as its ability to hold other molecules in a solution.
Cusps - peaks or raised areas of a tooth which usually fit into a fossa on the opposing tooth.
Cytokines -chemical messengers that allow neighbouring cells to communicate with each other. They are paracrine messages as distinct from endochrine or hormonal messengers. There are several main families of cytokines including growth factors , neurotransmitters, , lymphokines and many others. The method of communication involves detection of the chemical message, a ligand , by receptor proteins (for example an integrin on the cell membrane of the receiving cell. The result of the message is a shift in the level of gene expression or the expression of new genes and altered cell behaviour. Cytokines are complex as they sometimes inhibit and/or facilitate the actions of each other.
Cylasm - the contents of the cell, not including thenucleus.
Cytoskeleton - a system of fine filaments which cross the cell in all directions, helping11 toand keep or change its shape. There are three main types of filaments; in order of decreasing size they are, microtubules, microfilaments and intermediate filaments.
Cytotoxins - products released by bacteria which are toxic to other living cells.