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

I am placed inside your chest cavity as two air sacks-or bellows-surrounded by your muscles. I took my first breath right after birth and I still keep working non-stop. Even while you are sleeping, I fulfill my function with the automatic command I receive from the respiratory center at the back of your brain. My close friend Heart started working even before me while you were in the womb. I was resting then; actually I hadn’t even formed fully. As all your needs like food and oxygen were met in the body of your mother-whose heart you occasionally break-I didn’t have to make extra effort to get air, being filled and emptied. Even if I had attempted to do so, I would have had no chance of succeeding; since you were contained in the amniotic fluid, an attempt to breathe could have caused you to drown.

The first breath I take after birth is critical and rather difficult, since the windpipe is still much narrower than normal. On the other hand, the number of my alveoli where oxygen exchange with the capillaries is realized is so high in relation to body size that it balances the situation. When I make my first move and fill with air, I put pressure on the arteries and veins. Then the vessel directly connecting my artery to my mother’s aorta is dismissed, the curtain between the valves is closed and the blood circulations are separated. If this curtain is not properly closed and a gap remains in between, the oxygen-rich blood and the used-up blood mix and result in the disease known as cyanosis-or “blue baby” syndrome. As these two kinds of blood mix, the tissues are not supplied with sufficient oxygen and the white parts of the skin and eyes assume a bluish appearance.

Turning blue-purple due to lack of oxygen in the tissues is the same for smokers. Cigarettes-my archenemy-contain hundreds of toxic substances, such as carbon monoxide, which combine with the hemoglobin in blood and prevent oxygen transfer. Therefore, the lips of smokers turn slightly purple. You need to be careful with the air you inhale. The windpipe which brings air into me is covered with a ciliated epithelial tissue which catches the dust brought along and sweeps it outside. While you are asleep, the vibrating cilia of this sweeper work throughout the night and in the morning you get rid of the outcome of their propulsion by clearing your throat. However, every draw of a smoker kills 800–1,000 of our ciliated epithelial cells. After some time, they become unable to sweep the toxins (carbon, sulfur, lead, etc) inhaled with the air. I can’t stand it anymore! The increased air pollution is already putting enough strain on us… this habit is just too much for a lung to handle! It is just… an open invitation for cancer! Sorry, Peter, I didn’t mean to be rude. I appreciate that you don’t smoke, but I wish those who do would realize how splendid a mechanism they are destroying.

Now let me tell you about what a work of art I am. As you also know, art in a structure becomes more meaningful with functionality. As is the case with my other friends with which I work in your body, I am perfectly made to fulfill my duty. In other words, never mind forming an organ like me as a consequence of molecules and cells accidentally coming together, even a single protein molecule in my structure does not come to existence through unconscious causes.

With every breath you take, the pressure of the oxygen within the air inhaled rises, so it passes through my membranes by diffusion and into the adjacent capillaries; there it combines with hemoglobin molecules. At the same time, the carbon dioxide passes through the same membranes into me, and I dispose of it. Both of these are easier said than done! You breathe 13–14 times a minute and the whole thing is repeated over and over. As I keep expanding and contracting during breathing, which you are unaware of most of the time, first of all I need to be very flexible. Together with this flexibility, my most important quality is having the largest possible surface area within the smallest volume. My surface area of around 100m2 (as large as a tennis court) is made to fit into your chest cavity in the form of thin membranes so that my large surface allows gas diffusion. These membranes need to be kept wet; a special fluid is secreted as a precaution and respiration is realized smoothly. Without this fluid, my membranes would just stick together, unable to carry out their duty.

You can compare the course of the air inhaled to that of a car passing from a highway onto increasingly smaller roads and in the end reaching a dead end in the small sacks named alveoli. The air coming in through the mouth and nose unites at the expressway named the trachea, or the windpipe, which is 15cm long and 2–3cm in diameter. Incidentally, I have a couple of things to tell you about the way you breathe. As a matter of fact, inhaling is the duty of the nose. I’m sure it also has a lot to say as well, but let me just mention a simple fact about it. Now, you should inhale through your nose, so that the air you take in gets warm, wet, and is cleaned from dust. If you try to breathe this way, you do not trouble me much, and reduce the risk of catching a cold or an infection of upper respiratory system. Inhaling through the mouth helps dust and germs get into me and you might contract various illnesses from bronchitis to pneumonia. Now you know why kids who have adenoids who sleep with their mouth open get ill so easily. Sorry, I couldn’t help speaking on behalf on the nose.

Well, what were we talking about before that? Oh yes! The ways through which the inhaled air passes. As the name suggests, the windpipe which makes the air reach me is a cylindrical tube surrounded by 16–20 cartilaginous rings. As it is placed beside the esophagus, one side of the rings is made of soft cartilaginous tissue instead of hard, so that they don’t hinder swallowing. The muscular tissue near these rings helps them widen and narrow during respiration or coughing. I sometimes warn you by making you cough. Maybe it seems to be a disturbance, but if I don’t push out air by coughing through the contracted windpipe, contaminants can clog me up and cause you to suffocate. Therefore, the burst of air-what you call a cough-is a great blessing to you.

The sound system at the tip of the windpipe is another wonder. The used air I send out vibrates the cords in that voice-box and produces such melodies, gives voice to such speech! The air divides into the two lungs. My two sides are not symmetrical; the one on the right is divided into three, and the one on the left into two. I think this was meant to make room for the neighbor on the left, the heart. In addition, if there’s any cancer growth in me, the diseased part can be taken out by an operation and I can keep on functioning. God knows the wisdom behind this form. After that, these main bronchi separate into 8–10 thinner branches, like highways connecting to narrower roads. This branching resembles a tree turned upside down. At the tips of these thin branches are the respiratory bronchioles resembling clusters of grapes. The small spheres which make up the cluster are the end of the road and are the most vital parts. These spheres named alveoli are made of very thin membrane and they are surrounded by a net of capillaries (picture 5). These are the functional spots where gas exchange is realized.

I hang in the thorax with veins and arteries all around. There are two layers of protective membrane over me. One of them is stuck on me, whereas the other is stuck on the ribs which form the chest cavity. There is a fine and slippery fluid in between these two layers and it neutralizes the friction every time I inflate and deflate. If it hadn’t been placed there, I would wear out and be damaged. As I inflate during inhalation, the chest cavity should expand simultaneously to make space for me. If it weren’t given a flexible form, I would fail to breathe and you would eventually die. Fortunately, the protective set of ribs and their connection with the spine are flexible enough to make me work comfortably. In addition, the dome-shaped muscular partition (diaphragm) separating the thorax from the abdomen contracts and pushes down the organs in the abdomen. Thanks to the simultaneously programmed movement of both the ribs and the diaphragm I inflate with air and expand.

Being in constant contact with the outer environment makes me susceptible to various diseases. Coughing is among the foremost signals I give in the case of disease, and sometimes-excuse me-I produce a mixture of blood and phlegm. Also, I may have difficulty in breathing and warn you with chest pain. You should be alert to my signals. If bacteria and viruses infect me, they might reproduce inside my air sacs, and cause stiffening and suppuration.

I am particularly sensitive to allergic disorders. When the straight muscles on the walls of my bronchi contact an alien substance, pollens for instance, the consequent histamine secretion makes my muscles contract. In addition, allergic diseases, which can affect blood vessels, affect me a lot since I happen to be one of the major organs contributing to blood circulation. As a result of the contraction of my bronchial muscles and difficulty in disposing of the mucus I secrete to defend myself, I have trouble with breathing-you call it asthma.

In addition to this, we can mention diseases like emphysema, acute or chronic bronchitis as problems I frequently face. Even your anger has a great impact on me. Breathing becomes more difficult immediately.

Peter, I’m sorry, it is not possible to summarize a work of art like me within a few pages, but I need to stop now… but please, keep away from polluted areas and cigarette smoke! Send me as much fresh air as you can. And even though you mostly take me for granted, like my other teammates, please reflect upon what a blessing I am.

Irfan Yilmaz is a professor of biology at Dokuz Eylül University, Izmir, Turkey.