what does mucus do in the respiratory system
Mucus In the human respiratory system, mucus, also known as airway surface liquid (ASL), aids in the protection of the lungs by trapping foreign particles that enter them, in particular, through the nose, during normal breathing.[3] Further distinction exists between the superficial and cell-lining layers of ASL, which are known as mucus layer (ML) and pericilliary liquid layer (PCL), respectively.[4] "Phlegm" is a specialized term for mucus that is restricted to the respiratory tract, whereas the term "nasal mucus" describes secretions of the nasal passages.
Mucus In the human digestive system, mucus is used as a lubricant for materials that must pass over membranes, e.g., food passing down the esophagus. Mucus is extremely important in the intestinal tract. It forms an essential layer in the colon and in the small intestine that helps reduce intestinal inflammation by decreasing bacterial interaction with intestinal epithelial cells.[16] A layer of mucus along the inner walls of the stomach is vital to protect the cell linings of that organ from the highly acidic environment within it.[scientific 1] Mucus is not digested in the intestinal tract. Mucus is also secreted from glands within the rectum due to stimulation of the mucous membrane within.[citation needed]
Mucus Nasal mucus is produced by the nasal mucosa; and mucus lining the airways (trachea, bronchus, bronchioles) is produced by specialized airway epithelial cells (goblet cells) and submucosal glands. Small particles such as dust, particulate pollutants, and allergens, as well as infectious agents and bacteria are caught in the viscous nasal or airway mucus and prevented from entering the system. This event along with the continual movement of the respiratory mucus layer toward the oropharynx, helps prevent foreign objects from entering the lungs during breathing. This explains why coughing often occurs in those who smoke cigarettes. The body's natural reaction is to increase mucus production. In addition, mucus aids in moisturizing the inhaled air and prevents tissues such as the nasal and airway epithelia from drying out.[5] Nasal and airway mucus is produced continuously, with most of it swallowed subconsciously, even when it is dried.[6]
Wastewater If the wastewater contains human feces, as is the case for sewage, then it may also contain pathogens of one of the four types:[2][3]