Mucus << MYOO kuhs >> is a thick, clear, slimy fluid found in the nose, mouth, and other organs and passages that open to the outside of the body. It is made up mostly of a compound of protein and sugar. This fluid is produced by cells in the mucous membranes and covers the surfaces of the membranes.
Mucus performs two principal duties. It provides lubrication for material which must pass over the membranes, such as food passing down the esophagus (food tube). It also catches foreign matter and keeps it from entering the body. The mucous membranes of the nose, sinuses, and trachea (windpipe) are covered with fine hairlike structures known as cilia. The cilia contain microscopic muscles that enable them to rhythmically move back and forth. The motions of the cilia cause the mucus to carry bacteria and dust up the trachea to the nose and throat where it can be swallowed or blown out.
See also Cold, Common; Cystic fibrosis; Membrane; Mouth; Nose.
