You can survive without food for weeks. You can live without water for days. But if you hold your breath (lungs) , severe discomfort sets in after mere seconds. And just four minutes of oxygen deprivation can cause brain damage and death. Yes, oxygen is the prime need of the human body!
You probably do not have much control over the quality of the air you breath. Nonetheless, you need air, and you need it now! How do you survive when the air is too cold or too hot or too dirty? How do you extract life - sustaining oxygen from such air, and how does the oxygen reach every part of your body? How do you rid your body of carbon dioxide, a gas? All of it happens thanks to your marvelously designed lungs.
The Lungs At A Glance
Your lungs are the two main organs of respiration. Ideally located inside your rib cage, they lie on either side of the heart. Your right lung has three sections, or lobes, and your right lung has two lobes. At first glance the texture of the lung tissue may appear to resemble a sponge.
The Lungs reach downward to the diaphragm, a powerful sheet of muscle that separates the chest cavity from the abdominal cavity. The diaphragm is the most important muscle of respiration, contributing to the constant inflation and deflation of the Lungs. From the diaphragm, your lungs extend all the way up into the base of your neck. A thin membrane covers each lung. This membrane, or pleura, also lines the inside of the chest wall. The space between the two layers of the pleural membrane is filled with a lubricating fluid. This fluid enables the Lungs and the rib cage to slide easily, without friction, during respiration.
Some 25 to 30 different types of cells in the Lungs have now identified by scientists. Various muscles and nerves, bones and cartilage, blood vessels, fluids, hormones, and chemicals all play key role of the functioning of the Lungs. Although certain aspects of the Lungs are still not fully understood by scientists, let us acquaint ourselves with some of the many features that are understood.
Lungs Being A "Tree" Of Airways
Your respiratory tract is essentially an interconnecting series of tubes and passage ways. Before air reaches your lungs, it has quite a journey to make. First, the air flows from your nose or mouth into the pharynx, or throat. The pharynx is used both for the swallowing of food and for breathing. To prevent food and drink from entering your airways, a small movable lid known as the epiglottis blocks the entrance when swallow.
The air then passes through the larynx, where your vocal cords are located. Next is the almost 4 1/2-inch - long trachea, or windpipe, reinforced by about 20 C- shape bands of cartilage spaced throughout its length. The windpipe then braces into two one - inch - long tubes known as the main bronchi. One bronchus enters the left lung, the other enters the right lung. Inside the Lungs these tubes further divide into more branches.
This branching occurs again and again inside the Lungs until a structure resembling a tree is formed, with trunk, branches, and twigs. Of course, at each branding the airways become thinner and thinner. The air then enters the small branches, a network of miniature vessels called bronchioles, each with a diameter of about one twenty -fifth of an inch. The bronchioles lead to even smaller ducts, which send the air alveoli. These airsacs are arranged in bunches and resemble hangings clusters of grapes or tiny balloons. It is here that the treelike system of airways ends and the air reaches its final destination.
The Final Threshold
When it reaches its final threshold, the air you breath is contained within the extremely thin walls of the alveoli. They measure only 0.00002 inch across. The paper used in this magazine is about 150 times as thick as the walls of the alveoli!
Each one of these tiny alveoli is covered with a web of blood vessels know as pulmonary capillaries. These capillaries are so narrow that only one red blood cell can pass through at time! And the walls are so thin that the carbon dioxide in the blood can seep through into the alveoli. The oxygen, in turn, passes in the opposite direction. It exists the alveoli to be absorbed by the red blood cells.
Each one of these red blood cells, or corpuscles, traveling in single file, remains in the pulmonary capillaries for about three fourths of a second. This is plenty of time for the carbon dioxide and the oxygen to exchange places. This movement of gases is by a process known as diffusion. The oxygenated blood then passes into larger veins in the Lungs, eventually reaching the left side of the heart, from which the blood is pumped throughout the body as the fuel of life. All told, it takes about one minute for all the blood in your body to pass through this intricately designed system!
Quality Control
As the air you breath passes through your nose and mouth, it is actually being processed by a quality - control station. When the air is too cold, it is quickly heated to an adequate temperature. When the air is too hot, it is cooled down. What happens when the air is too dry? The walls of your nose, nasal sinuses, throat, and other passageways are lined with a fluid called mucus. When you inhale dry air, moisture in the mucus evaporates into the air. By the time the air reaches the farthest point in your lungs, it has a relatively humidity of almost 100 percent. Interestingly, when you exhale, the air returns over half of its humidity to the mucus.
This quality - control system also includes a sophisticated air filter. During the course of one day, about 2,500 gallons of air pass through the Lungs. This air is often loaded with infectious agents, toxic particles, fumes, or other impurities. However, your system is designed to remove most of these contaminants.
Initially, the hairs and mucous membranes in your nose do their part in catching larger particles of dirt. Then, you have millions of microscopic, hairlike projections that grow on the walls of your airways. They are called cilia. Like paddles, they wave back and forth at a rate of about 16 times a second, pushing dirty mucus away from the Lungs. Your lungs also count on the services of special cells, called alveolar macrophages, designed to kill bacteria and trap dangerous particles.
Hence, the air you breath is conditioned and filtered before it reaches the most delicate tissues of your lungs. Indeed a marvel of design!
An Automatic System
Unlike food and water, oxygen can be drawn from the environment without any deliberate effort on your part. At a rate of some 14 breaths per minute, a healthy pair of lungs extracts oxygen from the air automatically. Even during sleep your lungs continue to work without your conscious supervision.
You also have the opinion of temporarily overriding this automatic system. Hence, you can deliberately control your breathing to some extent if you wish to do so. After all, would you want the mechanics of breathing to continue operating automatically while you swim under water? At a rate of 14 breaths per minute, would you have enough time to escape a smoke - filled room during a fire if you were unable to hold your breath? Of course, this automatic system cannot be bypassed for long periods of time. After some minutes at most, your lungs will inevitably return to their automatic mode.
But what activates the muscles to inflate or deflate your lungs during this automatic operation? The control center is located in the brain stem. Here special receptors monitor the level of carbon dioxide in the body. When there is an increase of carbon dioxide, messages are sent through a network network of nerves, which in turn activate the appropriate muscles of respiration.
This gives remarkable flexibility to your respiratory system. The Lungs can keep up with even abrupt changes in your activity. For example, during strenuous exercise, your body may use about 25 times as much carbon dioxide as it does when it is at rest. However, your lungs almost instantaneously adjust the frequency and the depth of your breathing in order to match your constantly changing oxygen requirements.
There are other sophisticated controls that enable the Lungs to function properly. For example, some muscles used for respiration are also used in other functions, such as swallowing and speech. These functions are kept in balance so that they rarely interfere with your breathing. And all of this is done without any conscious effort on your part. Yes, automatically!
Of course, many things may go wrong with the Lungs, especially when your resistance is low. To name just a few disorders, there are asthma, bronchitis, emphysema, lung cancer, pulmonary edema, pleurisy, pneumonia, tuberculosis, and number of bacterial, viral, and fungal infections.
But these disorders are not the result of faulty or inadequate design of the Lungs. Most lungs diseases result from exposure to pollutants, dusts, and vapors dumped into the environment by man. Millions today suffer from lung cancer, bronchitis, and emphysema because tobacco smoking and other self - inflicted abuses of the respiratory system.
Under normal circumstances, however, let me know how you cherish this awesome creation in the comments section.
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