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| protective secretion of the mucus membranes; in the gut it lubricates the passage of food and protects the epithelial cells; in the nose and throat and lungs it can make it difficult for bacteria to penetrate the body through the epithelium | ||||
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| cement consisting of a sticky substance that is used as an adhesive | ||||
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| any of various substances (soluble in water) that exude from certain plants; they are gelatinous when moist but harden on drying |