Mucus ( MEW -k? s ) is a slippery water secretion that produced by, and covering the mucous membranes. This is usually produced from cells found in the mucous glands, although it may also come from a mixed gland, which contains serous cells and mucosal cells. It is a thick colloid containing inorganic salts, antiseptic enzymes (such as lysozyme), immunoglobulins, and glycoproteins such as lactoferrin and mucin, produced by goblet cells in mucous membranes and submucosal glands. Mucus serves to protect epithelial cells (which line the channels) in the respiratory, gastrointestinal, urogenital, visual, and hearing systems; epidermis in amphibians; and gills in fish, against infectious agents such as fungi, bacteria, and viruses. The average human nose produces about one liter of mucus per day. Most of the resulting mucus is in the digestive tract.
Reinforced fish, hagfish, slugs, slugs, and some other invertebrates also produce external mucus. In addition to serving protective functions against infectious agents, such mucus provides protection against toxins produced by predators, can facilitate movement and can play a role in communication.
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In the human respiratory system, mucus, also known as airway surface liquid (ASL), helps protect the lungs by trapping foreign particles that enter them, in particular, through the nose, during normal breathing.. Further differences exist between the superficial layer and the ASL cell layer, known as the mucous layer (ML) and the pericilliary fluid layer (PCL), respectively. "Sputum" is a special term for mucus limited to the respiratory tract, whereas the term "nasal mucus" represents nasal passage secretion.
Nasal mucus is produced by the nasal mucosa; and mucus lining the airways (trachea, bronchi, bronchioles) are produced by special airway epithelial cells (goblet cells) and submucosal glands. Small particles such as dust, particulate pollutants, and allergens, as well as infectious agents and bacteria trapped in nasal or nasal passages and are prevented from entering the system. This event along with the continuous movement of the respiratory mucous layer to the oropharynx, helps prevent foreign objects from entering the lungs while breathing. This explains why cough often occurs in those who smoke. The body's natural reaction is to increase the production of mucus. In addition, the mucus helps to moisten the inhaled air and prevent tissues such as nasal epithelium and airways drying out. Nasal mucus and respiratory tract are produced constantly, with most swallowing involuntarily, even when dry.
Increased mucus production in the respiratory tract is a symptom of many common diseases, such as the common cold and influenza. Hypersecretion of mucus can occur in inflammatory respiratory diseases such as respiratory allergies, asthma, and chronic bronchitis. The presence of mucus in the nose and throat is normal, but an increased amount can inhibit a comfortable breathing and should be cleaned by blowing the nose or sputum of expectation of the throat.
Diseases involving mucus
In general, clean and thin nasal mucus, serves to filter air during inhalation. During the infection period, the mucus may change color to yellow or green either as a result of trapped bacteria or due to body reactions to viral infections. The green color of mucus comes from the heme group in the myeloperoxidase enzyme containing iron secreted by white blood cells as cytotoxic defenses during respiratory eruptions.
In the case of bacterial infections, bacteria trapped in clogged sinuses, breed in moist and nutrient-rich environments. Sinusitis is an uncomfortable condition that may include congestion of the mucus. Bacterial infections in sinusitis will cause the mucus to change color and will react to antibiotic treatment; viral infections usually heal without treatment. Virtually all sinusitis infections are viral and antibiotics are ineffective and are not recommended for treating typical cases.
In the case of viral infections such as colds or flu, the first stage and also the last stage of the infection leads to thin and clear mucus production in the nose or back of the throat. When the body begins to react to the virus (generally one to three days), the mucus thickens and may turn yellow or green. Viral infections can not be treated with antibiotics, and are the main avenue for abuse. Treatment is generally symptomatic; often it is enough to allow the immune system to fight the virus over time.
Upper respiratory tract
Increased mucus production in the upper respiratory tract is a symptom of many common ailments, such as the common cold. Nasal mucus can be removed by blowing the nose or by using nasal irrigation. Excessive nasal mucus, such as colds or allergies, due to vascular swelling associated with vasodilation and increased histamine-induced capillary permeability, may be treated cautiously with decongestant drugs. Mucus thickening as a "rebound" effect after excessive use of decongestants can cause nasal or sinus drainage problems and conditions that increase infection.
During the cold, dry season, the mucus lining the nasal passages tends to dry out, which means the mucous membranes must work harder, producing more mucus to keep the cavity lined up. As a result, the nasal cavity can be full of mucus. At the same time, when the air is exhaled, water vapor in exhaling as warm air fills the cold outside temperatures near the nostrils. This causes an excess amount of water to build up inside the nasal cavity. In this case, excess fluid usually comes out externally through the nostrils.
Lower respiratory channel
Excess mucus production in the bronchi and bronchioles, as may occur in asthma, bronchitis or influenza, results from chronic airway inflammation, and therefore can be treated with anti-inflammatory drugs. Mucociliary clearance disorders due to conditions such as primary tardive ciliary may also cause its accumulation in the bronchi. Dysregulation of mucus homeotasis is a fundamental characteristic of cystic fibrosis, an inherited disease caused by mutations in the CFTR gene, which encodes a chloride channel. This defect causes changes in the composition of the electrolyte mucus, which triggers hypabsorption and dehydration. Low volume, thick, and acidic mucus has reduced antimicrobial function, which facilitates bacterial colonization. The depletion of the mucous layer ultimately affects PCL, which becomes dehydrated, sacrificing cilia function and destroying mucociliary clearance.
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Digestive System
In the human digestive system, mucus is used as a lubricant for materials that have to pass through the membrane, for example, food passing through the esophagus. Mucus is very important in the intestinal tract. It forms an important layer in the colon and in the small intestine that helps reduce intestinal inflammation by reducing bacterial interactions with intestinal epithelial cells. The mucus layer along the inner wall of the stomach is very important to protect the cell layer of the organ from the very acidic environment inside. Mucus is not digested in the intestinal tract. The mucus is also secreted from the glands in the rectum due to stimulation of the mucous membranes inside.
The reproductive system
In the human female reproductive system, cervical mucus prevents infection and provides lubrication during intercourse. Consistency of cervical mucus varies depending on the stage of the woman's menstrual cycle. In ovarian cervical mucus clear, watery, and conducive to sperm; post-ovulation, the mucus becomes thicker and more likely to block sperm. Several methods of Fertility Awareness depend on the observation of cervical mucus, as one of the three primary fertility marks, to identify the fertile time of a woman at the midpoint of the cycle. Awareness of women's fertile period allows couples to have intercourse to increase the chances of pregnancy. It is also proposed as a method to avoid pregnancy.
Nature of mucus
Melting swelling capacity
Mucus is able to absorb water or dehydrate through variations of pH. The mucus capacity develops from the mucin bottlebrush structure in which the hydrophilic segment provides a large surface area for water absorption. In addition, the tunability of swelling effects is controlled by the effects of polyelectrolyte.
Effect of polyelectrolyte on mucus
Polymers with charged molecules are called polyelectrolytes. Mucosa, a proteelectric proteoglycans, is a major component of mucus, which gives the effect of polyelectrolytes in mucus. The process of inducing this effect consists of two steps: the attraction of ion-counters and the compensation of water. When exposed in a physiological ion solution, the charged group in the polyelectrolyte attracts the opposing ion with the opposite charge, thus leading to a gradient of solute concentration. Osmotic pressure was introduced to equalize the concentration of solutes throughout the system by encouraging water to flow from low concentrations to high concentrations. In short, the influx and outflux of water in the mucus, managed by the effects of polyelectrolyte, contribute to the capacity of swelling of the mucus' melodic.
The pH-tunable magnification mechanism
The ionic content of mucin is mainly supplied by acidic amino acids including aspartic acid (pKa = 3.9) and glutamic acid (pKa = 4.2). The amino acid charge will change with the environmental pH value due to acid dissociation and association. Aspartic acid, for example, has negative side chains when pH values ​​are above 3.9, while neutral side chains are introduced as pH values ​​falling below 3.9. Thus, the amount of negative charge in the mucus is affected by the pH value of the surrounding environment. That is, the effect of polyelectrolyte from mucus is largely influenced by the pH value of the solution due to the variation in the charge of the amino acid residue on the spinal cord. For example, the residue that is charged to the mucin is protonated at the normal pH value of the stomach, about pH 2. In this case, there is almost no effect of polyelectrolytes, resulting in a compact mucus with small swelling capacity. However, a bacterium, Helicobacter pylori, tends to produce bases to increase the pH value in the stomach, which causes the deprotonation of aspartic acid and glutamic acid, ie from neutral to negative charge. The negative charge in the mucus is greatly increased, thereby inducing the effects of polyeletrolyte and swelling of mucus. This swelling effect increases the pore size of the mucus and decreases the viscosity of the mucus, allowing bacteria to penetrate and migrate to mucus and cause disease.
Filling selectivity
High selective mucal permeability plays an important role in a healthy human state by limiting the penetration of molecules, nutrients, pathogens, and drugs. The distribution of charge in the mucilage serves as a selective diffusion barrier charge, thus significantly affecting the transport of agents. Among the particles with various zeta potential surfaces, cationic particles tend to have low penetration depths, which are neutral with medium penetration, and the anionic has the greatest penetration depth. Furthermore, the effects of charge selectivity change when the mucus status varies, ie the original slime has a threefold higher potential to limit the penetration of the agent than the purified mucus.
See also
- Alkaline mucus
- Empty nose syndrome
- Mucoadhesion
- Mucophagy
- Slime snail
- Sniffle
- Spinnbarkeit
Note
References
Source of the article : Wikipedia
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