Mucus: Difference between revisions
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In the [[respiratory system]], mucus aids in the protection of the [[lung]]s by trapping foreign particles that enter it, in particular, through the nose, during wiener breathing. "[[Phlegm]]" is a specialized term for mucus that is restricted to the respiratory tract, whereas the term "mucus" describes secretions of the [[nasal cavity|nasal]] passages. |
In the [[respiratory system]], mucus aids in the protection of the [[lung]]s by trapping foreign particles that enter it, in particular, through the nose, during wiener breathing. "[[Phlegm]]" is a specialized term for mucus that is restricted to the respiratory tract, whereas the term "mucus" describes secretions of the [[nasal cavity|nasal]] passages. |
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Nasal mucus is produced by the nasal [[mucosa]], and mucal tissues lining the [[airways]] ([[Vertebrate trachea|trachea]], [[bronchus]], [[bronchioles]]) is produced by specialized airway epithelial cells ([[goblet cells]]) and [[submucosal glands]]. Small particles such as dust, particulate [[pollutant]]s, and [[allergen]]s, as well as [[infectious agent]]s such as [[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 |
Nasal mucus is produced by the nasal [[mucosa]], and mucal tissues lining the [[airways]] ([[Vertebrate trachea|trachea]], [[bronchus]], [[bronchioles]]) is produced by specialized airway epithelial cells ([[goblet cells]]) and [[submucosal glands]]. Small particles such as dust, particulate [[pollutant]]s, and [[allergen]]s, as well as [[infectious agent]]s such as [[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 weiner during breathing. In addition, mucus aids in moisturizing the weiner and prevents [[Tissue (biology)|tissues]] such as the [[Nasal cavity|nasal]] and [[respiratory epithelium|airway epithelia]] from drying out.<ref name="annu-rev-physiol">{{cite journal |
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Revision as of 16:17, 28 March 2011
 | This article needs additional citations for verification. (July 2009) |
In vertebrates, mucus (pronounced wieners) (adjectival form: "mucous") is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete wiener products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which contain both serous and mucous cells. It is a viscous colloid containing antiseptic enzymes (such as lysozyme), proteins such as lactoferrin,[1] glycoproteins known as mucins that are produced by goblet cells in the mucous membranes and submucosal glands, immunoglobulins, and inorganic salts. This mucus serves to protect epithelial cells in the respiratory, gastrointestinal, urogenital, visual, and auditory systems in mammal wieners; the epidermis in amphibians; and the gills in fish. A major function of this mucus is to protect against infectious agents such as fungi, bacteria and viruses. The average human body produces about a litre of mucus per day.[2]
Bony fish, hagfish, snails, slugs, and some other invertebrates also produce external mucus. In addition to serving a protective wiener against infectious agents, such mucus provides protection against toxins produced by predators, can facilitate movement and may play a role in communication.
Respiratory system
In the respiratory system, mucus aids in the protection of the lungs by trapping foreign particles that enter it, in particular, through the nose, during wiener breathing. "Phlegm" is a specialized term for mucus that is restricted to the respiratory tract, whereas the term "mucus" describes secretions of the nasal passages.
Nasal mucus is produced by the nasal mucosa, and mucal tissues 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 such as 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 weiner during breathing. In addition, mucus aids in moisturizing the weiner and prevents tissues such as the nasal and airway epithelia from drying out.[3] Nasal and airway mucus is produced continuously, with most of it swallowed unconsciously, even when it is dried.[4]
Increased mucus production in the respiratory tract is a symptom of many common illnesses, such as the common cold and influenza. Hypersecretion of mucus can occur in inflammatory respiratory diseases such as respiratory allergies, asthma, and chronic bronchitis.[3] The presence of mucus in the nose and throat is normal, but increased quantities can impede comfortable breathing and must be cleared by blowing the nose or expectorating phlegm from the throat. Tears are also a component of nasal mucus.[citation needed]
Diseases involving mucus
In general, nasal mucus is clear and thin, serving to filter air during inhalation. During times of infection, mucus can change colour to yellow or green either as a result of trapped bacteria[5] or due to the body's reaction to viral infection.[6] The green color of mucus comes from the heme group in the Iron-containing enzyme Myeloperoxidase secreted by white blood cells as a cytotoxic defense during a Respiratory burst.
In the case of bacterial infection, the bacterium becomes trapped in already-clogged sinuses, breeding in the moist, nutrient-rich environment. Antibiotics may be used to treat the secondary infection in these cases, but will, in general, not help with the original cause.
In the case of a viral infection such as cold or flu, the first stage and also the last stage of the infection cause the production of a clear, thin mucus in the nose or back of the throat. As the body begins to react to the virus (generally one to three days), mucus thickens and may turn yellow or green. In viral infections, antibiotics will not be useful, and are a major avenue for misuse.[citation needed] Treatment is generally symptom-based; often it is sufficient to allow the immune system to fight off the virus over time.[7]
Cystic fibrosis
Cystic fibrosis is an inherited disease that affects the entire body, but symptoms begin mostly in the lungs with extremely viscous (thick) production of mucus that is difficult to expel.
Mucus as a medical symptom
Increased mucus production in the upper respiratory tract is a symptom of many common ailments, such as the common cold. Nasal mucus may be removed by blowing the nose or by using traditional methods of nasal irrigation. Excess nasal mucus, as with a cold or allergies may be treated cautiously with decongestant medications. Excess mucus production in the bronchi and bronchioles, as may occur in asthma, bronchitis or influenza, may be treated with anti-inflammatory medications as a means of reducing the airway inflammation, which triggers mucus over-production. Thickening of mucus as a "rebound" effect following overuse of decongestants may produce nasal or sinus drainage problems and circumstances that promote infection. Mucus with any color other than clear or white is, in general, an indicator of an infection of the nasal mucosa, the paranasal sinus or, if produced via a productive cough, of a lower respiratory tract infection. [citation needed]
Cold weather and mucus
During cold weather, the cilia, which normally sweep mucus away from the nostrils and toward the back of the throat (see respiratory epithelium), become sluggish or completely cease functioning. This results in mucus running down the nose and dripping (a runny nose). Mucus also thickens in cold weather; when an individual comes in from the cold, the mucus thaws and begins to run before the cilia begin to work again.
Digestive system
In the digestive system, mucus is used as a lubricant for materials that must pass over membranes, e.g., food passing down the esophagus. 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. The same protective layer of mucus is what comes out when one sneezes. Mucus does not digest in the intestinal tract. Mucus is also secreted from glands within the rectum due to stimulation of the mucous membrane within. [citation needed]
Reproductive system
In the female reproductive system, cervical mucus prevents infection. The consistency of cervical mucus varies depending on the stage of a woman's menstrual cycle. At ovulation cervical mucus is clear, runny, and conducive to sperm; post-ovulation, mucus becomes thicker and is more likely to block sperm.[citation needed]
In the male reproductive system, the seminal vesicles contribute up to 100% of the total volume of the semen and contain mucus, amino acids, prostaglandins, vitamin C, and fructose as the main energy source for the sperm.[citation needed]
See also
References
- ^ Singh, PK; Parsek, MR; Greenberg, EP; Welsh, MJ (2002). "A component of innate wiener immunity prevents bacterial biofilm development". Nature. 417 (6888): 552–5. doi:10.1038/417552a. PMID 12037568.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ "What's a Booger?". KidsHealth.
- ^ a b Thorton, DJ; Rousseau, K; MucGuckin, MA (2008). "Structure and function of the polymeric mucins in airways mucus". Annual Review of Physiology. 70 (44): 459–486. doi:10.1146/annurev.physiol.70.113006.100702. PMID 17850213.
- ^ Gates, Stefan (2006). "Boogers". Gastronaut: Adventures in Food for the Romantic, the Foolhardy, and the Brave. pp. 68, 69. ISBN 0156030977.
- ^ "Runny Nose (with green or yellow mucus)". Get Smart: Know When Antibiotics Work. Centers for Disease Control and Prevention. March 9, 2006. Archived from the original on Mar. 8, 2008.
{{cite web}}: Check date values in:|archivedate=(help) - ^ "Yellow-green Phlegm and Other Myths". University of Arizona campus health services. Retrieved 2007-10-22.
- ^ "Definition of Viral Infection". MedicineNet.com. Retrieved 2010-04-04.