Some mucous membranes secrete mucus, a thick protective fluid. It contains numerous tubular mucous glands, which empty viscous alkaline mucus into the lumen. Lysozyme is abundant in secretions including tears, saliva, human milk, and mucus. In the pharynx, the pharyngeal glands secrete mucus. Inflammation of the lungs and excess mucus are common sources of breathing difficulties. The stool may contain blood, mucus, or pus. Maxillary antral washout involves puncturing the sinus and flushing with saline to clear the mucus. The whole burrowing process is aided by the secretion of lubricating mucus. This along with some stickiness provided by the secretion of mucus provides adhesion. Chronic bronchitis is a respiratory disease marked by overproduction of mucus and mucins. Symptoms typically include a chronic cough with mucus production. This, along with some stickiness from the secretion of mucus, provides adhesion. This appearance refers to the mixture of sloughed mucosa, mucus, and blood. CFTR is involved in the production of sweat, digestive fluids, and mucus. The most common clinical signs are haemorrhages of the skin and mucus membranes.