Aromatherapy involved inhaling pleasant smells and is a non-medicinal form of treatment for various psychological disorders. A nice smell triggers hormones of happiness (serotonin, dopamine, oxytocin, and endorphin) and helps overcome depression by stimulating the brain. A smell disorder is a malfunction that might even indicate neurological and psychological illnesses. One of the most crucial parts of the brain that is impacted by Parkinson’s or Alzheimer’s is the region that specializes in sense of smell. We mostly fail to notice what a blessing it is to be able to smell until we lose it. Otherwise, we are exposed to thousands of different smells every day.

Even minor issues with the nose can cause major inconveniences. Nasal congestion lessens the quality of everyday life: it is hard to sleep with a congested nose; even if you manage to fall sleep, the quality of sleep drops significantly.

The magnificent functions of the nose are as follows:

1. Sense of smell enables us to identify beneficial and harmful things and keep away from harmful ones. The nose helps spread the feeling of peace and happiness produced by nice smells that influence the spirit through the brain (olfaction).
2. The nose helps protect the respiratory passage from diseases by moistening and heating the inhaled air as it is carried to the lungs and cleaning foreign objects from the lungs with the mucus it secretes (inspiration and regulation).
3. It regulates the resonance of sound vibrations formed in the vocal cords, thereby virtually acting as loudspeakers (phonation).

These functions are miraculous, and yet we never contemplate them or their perfect engineering.

The nose: our body’s air-conditioning device

Before inhaled air reaches our lungs, it passes a turbulent current through the nose, which is by all means a perfect air-conditioning device and air filter.

Air that enters the nasal cavities through the nostrils flows through inner nasal canals to the nasopharynx (upper-frontal pharynx). It then flows down the pharynx to the larynx and finally to the lungs. Inside the nostrils are hairs that trap and filter dust, sand, pollen, and little bugs. Cleaned of these particles, air then passes through canals (meatus), which are anatomical engineering wonders in each nostril, and over turbinal structures (conchae) (Figure 1).

The exterior of these scroll-shaped canals in the nasal cavity are lined with a moist layer that secretes the fluid called mucus. Thanks to the magnificent architecture of the air conditioning chimney made up of these canals and folds, particles of dust are retained by this mucosa membrane. On this membrane there are also thin hairs (cilia) which constantly wave to and fro. This movement carries particles of dust not toward the lungs but toward the nostrils, which are then expelled when the person sneezes or blows the nose. If it were not for this precisely built structure, the inhaled air would directly go to the lungs without undergoing cleaning.

The inner working of the nose also heat or cool air, as necessary. The mucosa that lines the inside of the nose is rich in capillaries and mucus secretion. As inhaled air travels through the nose, it both warms up by absorbing heat from the blood in the mucosa veins and gains moisture by absorbing it from the mucosa. For example, when a person inhales through air from a room where the temperature is 20-22°C (68-71°F), the air heats up to 32-35°C (89-95°F) and becomes 95-98% moist by the time it reaches the larynx. If the same person breathes in through the mouth in the same room, the inhaled air can warm only up to 28–30°C (82-86°F) and reach a moisture point of 80-85%.

Without the nose, air would not be heated, moistened, and purified. The dusty, dirty, or cold air we inhale would directly go to the lungs, which would cause frequent illnesses in them and the upper respiratory tract.

How do we smell?

The nose is created with the ability to distinguish about ten thousand different smells. Its magnificent architecture is a perfect means of transport that facilitates the sense of smell in our brain, which is the real center of smell in our body. As this sense of smell function in our body, we take pleasure out of it in our soul.

The “smell molecules” communicated through the air first reach the receptors in the “olfactory epithelium” in the upper region of the nose that is equipped with a multitude of nerve cells. The stimulus that is converted into an electrical signal in this epithelium is conveyed to the smell center in the brain through olfactory nerves (Figure 2). All this process the smell molecules go through in the nose and the brain interact and impact with our soul in such a subtle way that we take delight and even be healed.

The sense of smell in certain animals (especially in dogs, moths, and some fish species) is hundreds of times more sensitive than in humans. For these animals, it is crucial for finding food and their survival.

The inability to perceive smells, or “smell blindness” (also called “anomia” in medicine), can be temporary or permanent depending on the underlying factor. Anomia is usually temporary in cases of the flu, cold, bad sinus congestion, or allergies. A decrease in olfactory sensitivity (hyposmia) can also be caused by nasal congestion, enlarged adenoids, nasal polyps, nasal deviations, or concha bullosa, which prevent air currents from reaching the olfactory region. The sense of smell usually recovers when these anatomical abnormalities are corrected; only in cases when duration of sinusitis is prolonged, namely when it becomes chronic, does loss of smell become permanent.

The impact of the nose on our voice quality

We can feel the effect of our nose on our voice quality, such as when the voice changes due to congestion or closing the nostrils with our fingers. Experienced physicians can immediately diagnose nasal congestion from the way a patient talks. Life is indeed an ordeal for people who cannot breathe easily through their noses.

Air cleared of germs

Nasal mucus is a slightly acidic secretion that carries an antibody called “immune globulin A” (IgA). Its slight acidity as well as the antibody in it allows the mucus to eliminate various germs, and the respiratory tracts are thus protected against perilous sources of illness.

The tiny sweeping hairs that line the interior of the nose can break down or stop working altogether because of certain germs, particularly viruses that cause the flu, filthy and dry air, sulfur dioxide, carbon monoxide, and cigarette smoke. Because nasal cleaning is disrupted, disease-inducing microorganisms can easily cause upper respiratory tract inflammation and other serious infections.

 The nose’s role in taste

Smell is crucial for a better perception of taste. Indeed, when there is a problem with the function of smell, a person’s sense of taste suffers, too. Nice smells have a favorable impact on the sense of smell. If we could not detect the bad smell of a rotten, harmful food item, we would not be able to stop ourselves from eating it and harming our body.

The importance of smell is highlighted in religious traditions. It is reported that the Prophet Muhammad, peace be upon him, mentioned putting on pleasant perfumes among other things that were the traditions of the messengers of God. Clippings from mush, camphor, amber or aloeswood were also burnt in the Prophet’s home for their pleasant scents.

Humans rarely consider their sense of smell. In fact, we tend to take it for granted. But through the nose’s perfect design, we are to smell and taste so much of the world around us, which is surely an everyday miracle.

Figure 1: The magnificent design of the anatomy of the nose

Figure 2: The awe-inspiring structure of the olfactory region

We have to breathe in order to live. The oxygen, which is essential for us, is cleansed and its heat and moisture are regulated as it passes turbulently down the narrow channels of the nose. Thus, the air we breathe is made ready for service to the alveolus in the lungs. In this way, approximately fifteen square meters of air, which is inhaled with 23,000 breaths daily, is processed in the nose.

The area behind the nostrils has been equipped with an acclimating system that is astonishingly sensitive and which scientists have difficulty explaining. This system not only regulates the heat and moisture of air, but at the same time, it possesses a mechanism that perceives harmful molecules in the contents of the air and gives an alarm. By stimulating the nose’s mucosa, this alarm mechanism shows activity by evacuating with the speed of a hurricane the air in the lungs via the nose and mouth-this is what we call sneezing. As a result of sneezing, the harmful matter that entered the body with the inhaled air is expelled from the body.

How and why do we sneeze?

It is a Divine blessing that we do not become ill frequently in spite of the millions of microorganisms that enter our body everyday mainly through the air we breathe. The microbes that enter our noses with the air we breathe are caught together with dust by tiny hairs here called cilia. Those that escape here are asked for a password by the anti-bacterial mucus secretion emitted by the epithelium tissues in our noses. In order for smells to be perceived by the nerve cells of molecules, the thickness of mucus must be around .06 mm. If the mucus layer were thicker, our sense of smell would be decreased, and if it were thinner, the defense system would weaken and cilia would be easily harmed. In addition, with its content and density, this secretion is responsible for filtering foreign particles in the air and for moisturizing the air to make it suitable. Because it is dangerous for things to pass this point, the body’s alarm that we call sneezing kicks in and microbes are expelled in this way. Sneezing is one of the most important defense mechanisms of the upper respiratory system. When the thresholds of the special nerve cells in the nose are stimulated, the signals reach the brain and the sneezing reflex kicks in. The mucus tissues are stimulated, mucus is secreted and the capillaries widen. Meanwhile an itching or tingling sensation is felt in the nose. As a result of the warning coming from the brain to the head, neck and stomach muscles, air is closed into the area where the vocal chords are and pressure is greatly increased in the lungs. Later, while the air is suddenly and loudly forced out, the foreign matter in the nose and respiratory path are thrown out. Because the nerves responsible for sneezing are also connected to the eyes, tears are usually secreted during sneezing and at this time the eyes involuntarily close.

In addition to the discomforts of the flu, the common cold, and bronchitis causing sneezing, external factors like nose polyps, flying pollen, dust, perfume, animal hairs and even suddenly looking at the light can also cause it. Because some people are sensitive to certain factors, they can be affected faster and they will sneeze. Some are more amenable to sneezing during certain periods. For example, it has been determined that pregnant women are more inclined to sneeze due to the hormonal change they are experiencing. It has also been established that the members of some families sneeze consecutively in certain numbers (3-5 times); this situation supports the idea that sneezing attacks can be hereditary. It is known that men sneeze more than women and that white people sneeze more than black people. One out of five people sneeze when they look at a bright light while walking in the dark. Due to the sudden reflection of light, the pupil of the eye contracts and the emission of tears increase. This emission reaches the upper division of the nose cavity by means of the tear ducts and, stimulating the mucus tissue in the nose, it triggers sneezing. In illnesses such as the common cold, the mucus in the nose quickly triggers sneezing because it is more sensitive.

Beware of cluster bombs

Sneezing is one of the rare moments when the body desires a situation different from its normal functioning. Sneezing and coughing lead to a movement of air strong enough to break the mucus bond, and as a result, droplets are formed. It has been established that the speed of air and the particles in it while being expelled from the mouth at this time is close to 100 miles per hour. Those who carry the viruses of illnesses like the flu scatter about close to one hundred million microorganisms during sneezing-like a cluster bomb. From 2,500–5,000 droplet seeds can remain in the air for hours in the cloudlet that has been formed. As the diameter of the droplet seeds decreases, their period of staying in the air increases. The diameter of droplet seeds that remain in the air for a long time and cause the spread of illnesses is between one and five microns.

Rather than food and drink, tuberculosis spreads by deep respiratory movements like sneezing and coughing via droplets loaded with bacillus. Dispersing in the air into smaller particles, the droplets are inhaled by healthy people by means of the respiratory path.

If necessary precautions are not taken in regard to a viral infection, it can spread throughout the world in one month, because the droplets carrying the virus can travel forty meters when you sneeze, six meters when you cough, and two meters when you talk. For this reason, illnesses like the flu which spread with droplets are frequently seen during the winter. For one person sneezing several times in places where there are crowds of people means that the virus spreads to hundreds of people within a few minutes.

Is sneezing beneficial?

The movement of cilia in the upper respiratory path is very important in regard to the health of the lungs. They hold the harmful matter coming with the air, trigger the sneezing reflex, and together with mucus, prevent them from entering the lungs, thus performing a very important protective duty. The expulsion from the body of matter that is probably harmful together with the air in the lungs is a blessing that provides a person with a great benefit. Consequently, formerly natural powders like black pepper known as snuff were breathed into the nose in order to sneeze. While sneezing, the brain and cardiovascular veins expand and tear and sinus ducts open; thus, the dead air we normally cannot exhale is forced from our lungs.

When sneezing, a high amount of pressure is generated in the body, especially in the stomach area and brain. Due to this pressure, a lot of blood goes to the cardiovascular veins, and in fact, serious situations like fainting can occur during sneezing attacks. However, sneezing is beneficial to a healthy heart. Fully closing the mouth and holding the breath while sneezing can bring about bursting and tearing in the lungs. The ribs can even break with an intense and unbalanced sneeze. If a person tries to stifle the sneeze after the sneeze reflex has occurred by closing his mouth and nose, he can harm the brain and bring on paralysis or when the pressure increases in the capillaries in the brain, bleeding can occur. In this situation, people, especially those who have undergone an operation, can be seriously harmed. In addition, veins in the eyes can expand and rupture. When sneezing is triggered, a person should relax and not prevent the sneeze.

In addition to providing protection against harmful things that have entered the respiratory system, sneezing is a reflex that is a means for relaxation, relief and invigoration of the body. If this reflex had not been put in the body, it would be difficult to escape many harmful things that would give discomfort. During sneezing, the rest period after diastole of the heart increases. This is probably the reason why we say, “Bless you” when someone sneezes. Prophet Muhammad, peace and blessings be upon him, said, “One of the six rights of a believer over another is to make a prayer when he or she sneezes,” and “One of the times when prayer is accepted is at the moment of sneezing.” It was related that the Prophet, peace and blessings be upon him, “covered his face with his hands or a cloth when he sneezed and he lowered his voice.”

We are being reminded of the value of our health which God bestows upon us anew each time we sneeze. Sneezing is a cloud of mercy not only for us, but also for those who witness this moment with prayer and with whom we share feelings of gratitude.

Adem Arikanli is a freelance writer from Turkey with an interest in health and biology.

Mucus is a viscoelastic gel-like material. It has been used to describe the coating and/or lining layers of vertebrates (e.g. fish, mammals) and invertebrates (e.g. coelomates, molluscs) (Rose, 1992). As noted earlier, in mammals the term mucus is restricted to the material covering the epithelial surfaces and providing an interface between the external environment and the epithelial layers. In vertebrates, this interface provides lubrication, maintenance of tissue hydration, and cytoprotection against proteases – a group of enzymes that break down the bonds amoung aminoacids – pH extremes, chemical irritants, and biological agents. Whereas invertebrate mucus has additional biological functions, like navigation, locomotion, and structural support (Denny, 1989). In the human both, the importance of these biological functions may vary depending on the location of the mucus: for example, in the respiratory tract, to clear the airways of inhaled particles: in the eyes, to prevent corneal surfaces from drying: in the reproductive tract, to protect the uterine cavity and control the survival and penetrability of the spermatozoa. However, there is one important function common to all systems, namely the maintenance of the mucosal water balance.

The composition of mucus

It is important to know something about the biological composition of mucus. In humans, this viscoelastic gel usually contains more than 90% water, 0.5-5% high molecular weight glycoproteins, termed mucins, and also a large number of other components such as electrolytes, lipids, plasma proteins and nucleic acids. Mucins are extremely large and heavily glycosylated molecules that consist primarily of a non-globular, thread-like polypeptide backbone and 0-linked oligosaccharide side chains. Within the mucin producing cells the molecules are found, without water, within large membrane-bound granules that fill the upper part of the cell. It appears likely that the mucins are the major determinants of mucus behaviour, and non-mucin constituents such as DNA, lipids and proteins are, when present, likely to influence the properties of the gel (Carlstedt, 1988). However, acidic mucopolisaccharides and glycoproteins are the major macro- molecular components of mucus in other animals, such as marine snail mucus (Rose, 1992).

In general, the gel forming mucin macromolecules have an oligomeric structure and are assembled from subunits via disulphide bonds. They can be fragmented into subunits by reduction of these disulphide bonds (Thornton. 1995). On the basis of their sensitivity to proteases it is believed that mucins typically contain two different types of domains that are highly glycosylated regions (rich in serine and threonin) and ‘naked’ hydrophobic regions that have lower substitution with carbohydrates. Where when and how does such a complex substance get synthesized, assembled and secreted? And what can happen if the process goes wrong or gets out of balance?

In the gastrointestinal tract

One of the common places where mucus has many vital functions is the gastrointestinal tract. The main site of production of intestinal mucin is the goblet (mucous) cell. However; there is a small amount of mucus production in columnar cells (intestinal epithelial cell). Mucus secretion is probably under both neural and hormonal control. However, little is known about exocytosis in which the membrane of the granules fuses with the apical plasma membrane, thereby releasing its contents.

In this tract, mucus forms a protective layer between the epithelial surface and the luminal compartment, and has been indicated in the mechanical protection of the gastrointestinal epithelial cells from bile acids, pH extremes, digestive enzymes, biological agents such as bacteria, virus and parasites, and mechanical damage. Also, in the stomach, mucus provides a mixing and diffusion harrier which protects the stomach wall from the damaging effects of the secreted hydrochloric acid which plays a big part in the digestion of our food. Bicarbonate ions are secreted into the unstirred mucus layer to help neutralize the acid and limit its harmful effects (Flemstrom, 1987). We are unaware of this function of mucus generally; however, when someone has a stomach or duodenal ulcer, or any types of gastritis, they have to take some anti- acidic drugs and so become aware of their neutralizing mucus blanket.

We know little about the involvement of gastrointestinal mucus in disease. It is suggested that there is a selective loss of a ‘specific’ mucin subpopulation in ulcerative colitis which is an inflammatory intestinal disease (Podoisky & Isselbacher, 1984). Many recent studies indicate that mucins secreted by colorectal carcinoma are immunologically and biochemically different from those in normal colon and adenomatous colon in which there is epithelial benign tumour and/or tumours in the colorectum (Gendler eta1., 1990; lass et al., 1994). Moreover, it has been shown that some components of mucus can be employed as a marker for colonic carcinoma and pre-cancerous conditions (Guang & Abdulkalam. 1995).

In the respiratory tract

Another common place for mucus is the respiratory tract, where mucus is produced by submucosal glands and by goblet cells interspersed among the ciliated respiratory epithelial cells. The cilia are like tiny hairs and are very numerous on epithelial cells of the upper respiratory tract. There maybe 250 or more cilia on the surface of a ciliated epithelial cell, arranged in regular rows. The ciliated epithelial cells, together with a thin mucus layer, constitute the mucociliary transport system designed to clear the airways from foreign particles such as dust, pollen, bacteria or other harmful particles. When we inhale these harmful particles into the lungs, a local stimulation of mucus secretion is evoked. The mucus blanket surrounds the particle and is moved by the cilia which beat in a rhythmical, wave-like manner into the trachea and from there it is swallowed to the gastrointestinal tract. In this propelling the gel towards the pharynx (the upper part of the trachea), the tips of the cilia interact with the mucus layer so that the energy can be passed from the cilia to the mucus blanket. If something goes wrong with the ciliated epithelium or the epithelium is depleted of mucus, this transport may not necessarily occur.

Although in healthy individuals goblet (mucous) cells represent on average 1/10 of ciliated cells, in a chronically obstructed airway (when diseases such as bronchitis, asthma, bronchorrhea and cystic fibrosis are present) the number of the goblet cells and of the submucosal glands increases markedly. In these particular diseases, hyperplasia of goblet cells, hypertrophy of submucosal glands and the hypersecretion of mucus are the prominent features of the pathological process. The most common inherited disease where mucus is very important is cystic fibrosis. This disease appears in about 1 in 2000 people born in Europe and America, although 1 in 20 people carry the defective gene. In this case mucus is stickier than normal and so the abnormally sticky mucus cannot be easily removed from the lungs. Instead of acting as the means for removing bacteria, the mucus becomes a breeding medium for them and the complications of the resulting infection ultimately lead to early death. 

In the reproductive tract

Besides the gastrointestinal and respiratory tracts, mucus is very important also in the reproductive tract. The cervical canal, the entrance to the upper reproductive tract, is filled with mucus whose biological functions are to protect the genital tract from infection and to control the survival and penetrability of the spermatozoa (male germ cell). The amount and physical properties of mucus vary during the ovulatory cycle. At ovulation, when the woman produces ova from her ovary, there is an increased hydration of mucus which results in a watery secretion with high spermatozoal penetrability and low viscoelasticity (Wolf et al., 1978). In contrast, during the luteal phase, the second part of the menstrual cycle, the mucus is scant, contains less water and provides an effective barrier to the spermatozoa (Carlstedt et al., 1988). During pregnancy a large mucus plug blocks the cervical canal in order to protect the uterine cavity including the baby from any external effects. If the composition of the mucus changes during the early stages of the pregnancy, this mucus plug may become defective and the pregnancy may result in abortion or premature birth. It has been shown that high levels of cell-surface MUC1 (a mucin gene product) inhibit both cell-cell and cell-matrix adhesion that is important in human embryo implantation and this occurs in the mid-secretory phase of the menstrual cycle (Aplin & Hey, 1995). Moreover, the changing of mucus composition may be an important factor in infertility, because it controls the survival and penetrability of the spermatozoa. Also, there is the same significant alteration in the biochemical characteristics of the mucus in endometrial carcinoma.

Alterations in mucus composition

As mentioned earlier, there are some notable alterations in the biochemical characteristics of mucins in many diseases. For example, in chronic obstructive respiratory disease excess mucus is present in airways. In cancer, one frequently finds abnormal carbohydrate structures on mucins that can serve as surrogate markers for tumour progression. Also, mucin peptide epitopes that are normally covered with carbohydrates become uncovered and can serve as markers. Since membrane mucins can function as anti-cell adhesion molecules, and their over expression in cancer may facilitate tumour dissemination and therefore metastases. However, there is still a lot of work to be done to understand biosynthesis, secretion and functions of the mucus, especially mucins, in healthy people or in diseased conditions. How is it that mucus can change in response to environmental influences, bacterial attack, or hormonal balance? What is the relationship between mucus and the progression of cancer or such kind of life-threatening diseases? It is clear that mucus is susceptible to almost infinite and rapid modification. When we understand how this capability is employed and controlled, we may be one step nearer to controlling sonic life-threatening diseases, such as cystic fibrosis, cancer, or some abnormal conditions, like infertility and miscarriage.

As a conclusion we can say that mucus may appear a sticky, tiresome, messy nuisance hut it is obvious that a life without mucus would he extremely uncomfortable. It is a gift of the Creator to all living beings, and a miracle, many of whose wonderful mysteries remain to he discovered. 

References

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• Carlstedt I. (1988) Mucus Gylcoproteins: Structure and Macromolecular Properties, Lund University Press, Lund,
• Denny M.W, (1989) ‘Intervertebrate mucus secretions: functional alternatives to vertebrate paradigms’. Symp. Soc. Exp. hal. 43, p. 337.
• Flemstrom (3. (1987) Physiology of Gastrointestinal Tract, Raven Press, New York, pp. 1011-29.
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• cloning and expression of human tumour-associated polymorphic epithelial mucin’. .J Biol. Chem. 265, pp. 15286-93.
• Guang Y.Y. & Abdulkalam MS. (1995) ‘A new monoclonal antibody, CMU1O, as a marker for colonic carcinoma and precancerous conditions’. Arch, Pathol. Lab. Med., 114, Mayc pp. 454-60.
• Jass JR., Robertson A.M. (1994) ‘Colorectal mucin histochemistry in health and disease: a critical review’, Pathol. Int,. 44, pp.487-504.
• Podolsky D. & Isselbacher K.J. (1984) Gastroenterology, 87, pp.99 1-8. Rose MC. (1992) ‘Mucins: structure, function, and role in pulmonary diseases’. The Am. Physiol. Soc., pp. L413-L429.
• ThorntonD.J., Howard M., Devine P.L.,. Sheehan J.K. (1995) ‘Methods for separation and deglycosylation of mucin subunits’. Analytic Biochemistry. 227, pp.162-7.
• Wolf DR Blasco L., Khan M.A., Litt M. (1978) , Fertil. Steril. 30, pp.163-9