I’m warning you; if you stop now, you will die! No, I’m not making a threat against your life for choosing not to read this article. I am talking about breathing. We rarely pay attention to it, but from twelve to twenty times a minute, hour after hour, day after day, we breathe. In fact, I can think of no act more integral to our physical being than that of respiration. Respiration begins at the protrusion from your face that you refer to as your nose. And although it is said that there is nothing “as plain as the nose on your face,” there is nothing “plain” about the human nose.
For example, when you go to sleep after a long day, your nose continues working, and actually plays a large role in movement. If you fall asleep lying on your right side, your right nostril will become clogged by drainage after a few hours. But, in such a case the nose will send out a silent signal to the brain in two hours that will stimulate movement and prompt you to turn over. This movement, in turn, will prevent your muscles from being cramped in the morning.
ITS ROLE IN RESPIRATION
The nose has little room to boast about its structural design. The nose is simply a cavity in the face stuck in between the brain and the mouth. One might say that we have two “noses,” since the nose is divided into two parts by a septum—a wall of cartilage.
One of the most important functions of the nose involves cleaning and conditioning the air so that it can be used in a safe fashion by the lungs. Every day, the nose must process about 500 cubic feet of air—about the size of a prison cell. A person’s lungs can even take in air from, say, Russia in wintertime, in which case the nose humidifies the air, since lungs require air that is fresh, clean, and warm—75 to 80 percent saturated, with a temperature in the 90s. To humidify air, the nose secretes approximately a quart of moisture a day. This moisture is sticky liquid called mucus. The hairs in the nostrils play a role in cleaning the air, but it is the mucus that bears the brunt of the labor. The mucus acts like a sort of flypaper, trapping particles and microorganisms that make it past the hairs. Obviously, the nose cannot allow this film of mucus to stagnate, so it provides a new cover every twenty minutes. To remove the old mucus, the nose is equipped with thousands of microscopic hairs that whip the film back to the throat so that it can be swallowed. The industrious cilia make about ten swipes per second.
It is no simple task for the nose to warm air as it enters the body. To accomplish this task, the nose has shelf-like protrusions from the nostril walls, called turbinates, that act as radiators. These tiny turbinates are covered with erectile tissue that possesses a relatively large blood supply, which provides the warmth for the incoming air.
THE NOSE—ITS ROLE IN SMELLING
“It” can save your life from a flaming fire, or it can help you to have an even greater appreciation for home-cooked meals. What could I be talking about? I am talking about your sense of smell, or olfaction, as scientists prefer to call it. Smells register in your brain, and then alert you of things that are pleasurable, unpleasant, or dangerous. This sense allows you to smell the smoke from a fire, and it permits you to enjoy the aroma of your grandmother’s homemade apple pie.
The olfactory system, which consists of the nose and sinuses, is designed to detect a variety of thousands of chemicals. The average person’s nose can detect over four thousand different scents. How is the nose able to detect odors? There is a patch of yellow-brown tissue about the size of a penny on the roof of each nasal cavity. Each patch has about ten million receptor cells, plus six to eight tiny sensory hairs that project from each cell. All of this is connected to the brain, which is just about an inch away. The brain processes the data and registers them for future use, eventually possessing the capability of matching various odors as being sweet, bitter, flowery, or any one of thousands of other scents.
THE RESPIRATORY SYSTEM
In essence, the role of the respiratory system is to take in oxygen and send it to the blood. Respiration is the process by which the body exchanges oxygen for carbon dioxide gas. The respiratory and the circulatory system form a tag team in a two-phase effort. The first phase is inhalation, by which air from outside the body is brought into the lungs. Oxygen from the lungs then passes into the heart, which pumps the oxygen-filled blood throughout the body. In the second phase of respiration, the bloodstream carries carbon dioxide to the heart, where it is pumped into the lungs and exhaled.
Air, which contains about 21% oxygen and 78% nitrogen, enters the body through the nose. The upper respiratory tract consists of the nose and the pharynx, or throat. The lower respiratory tract includes such things as the larynx, the trachea (which splits into bronchi), small branches of the bronchi called bronchioles, and the lungs (spongy, sac-like organs).
Breathing is dependent upon the activity of a group of specialized nerve cells in the medulla of the brain that comprise what is called the respiratory center. Impulses are sent down into the spinal cord and then into the phrenic nerves, causing contraction of the diaphragm and allowing inhalation to occur. Ventilation of the lungs is the result of contraction of the diaphragm.
Just before breathing in, the pressure inside the lungs is the same as the atmospheric pressure. The intercostal muscles contract, causing the rib cage to move upward and outward; simultaneously, the diaphragm contracts and is pushed downward. At the end of each breath, the diaphragm and intercostal muscles relax, and the diaphragm and chest wall return to their normal state. This fall of chest volume, combined with elasticity in the lungs, forces air to return to the atmosphere. During normal breathing, the diaphragm moves from one-half to one inch. But after your brisk morning jog, to choose just one example, the diaphragm will move three to four times more than usual (which causes the “heaving” feeling in your chest).
When air is inhaled, it travels down the back of the throat, the pharynx. The pharynx is approximately five inches long, and is lined with a protective mucous membrane that removes impurities from the air. The pharynx also includes the tonsils, which are flabby tissues containing white blood cells that fight diseases. Air then proceeds through the larynx. The larynx also prevents food and drink from entering the air passage so that choking does not occur.
Next, air descends through the trachea—a firm tube held open by crescents of tough cartilage arranged with one rung on top of the other. The trachea forks into two air pathways called bronchial tubes. One tube leads to the left lung, and the other leads to the right. As the bronchial tubes pass through the lungs, they divide into smaller air passages called bronchioles. These bronchioles branch into small balloon-like sacs called alveoli.
Alveoli are surrounded by a network of tiny blood vessels called capillaries. Oxygen taken in through the respiratory tract is here filtered and released into the bloodstream. The oxygen flows through capillaries to larger vessels that carry the freshly oxygenated blood to the heart where it is distributed to the rest of the body. Carbon dioxide is concentrated much higher in the capillaries than in the alveoli, which results in carbon dioxide diffusing into the alveoli. Exhalation forces the carbon dioxide back through the respiratory vessels and outside the body, and the process starts all over.
By examining the complexity of the respiratory system, we can see evidence of an Almighty Maker—Whom we should praise for having created us. The Bible reminds us: “Let everything that has breath praise the Lord” (Psalm 150:6). Indeed!
Ratcliff, J.D. (1975), I Am Joe’s Body (New York: Berkeley Publishing), pp. 35-40.
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