I am Joe’s right lung, and I claim the privilege of speaking since I am slightly larger than my partner in the left side of his chest. I have three lobed-sections while the left has only two. Joe would be surprised if he could see me. He thinks of me as a kind of hollow, pink football bladder hanging in his chest I am not much like that at all. I am not hollow–if you cut through me, I would look something like a rubber bath sponge. And I am not pink. I was when Joe was a baby. Now, a quarter of a million cigarettes plus half a billion breaths of dirty city air later, I am an unattractive slate gray with a mottling of black.
There are three separate, sealed compartments in Joe’s chest: one for me, one for the left lung one for his heart. I hang loose in my compartment, filling it completely, and weigh about 500 grams. I have no muscles and hence play a passive role in breathing. There is a slight vacuum in my compartment–so when Joe’s chest expands I expand. When Joe exhales, I collapse. It is simply a recoil mechanism. Let Joe puncture his chest wall in an accident and my vacuum is broken. I will hang loose doing no work, until healing takes place and the vacuum is reestablished.
Take a closer look at my architecture. Joe’s 10 centimeter-long windpipe divides at its lower end into two main bronchial tubes – one for me, one for my partner. Then branching begins in me – like an upside-down tree. First the larger bronchi, then the bronchioles 1/40 of a centimeter in diameter. These are simply air passages. My real work is done in my alveoli–grapelike bunches of minute air sacs. Flattened out, their tissue would probably cover a tennis court.
Each alveolus is covered with a cobweb of capillaries. Blood is pumped by the heart into one end of a capillary. Red cells pass through single-file–the passage taking about a second–and a remarkable thing takes place. Through the gossamer membrane of the capillary wall, the cells diffuse their cargo of carbon dioxide into my alveoli. At the same time, the cells pick up oxygen going the other way. It is a kind of gaseous swap shop–blue blood going in one end of the capillary, emerging refreshed and cherry-red– at the other.
Joe’s more important body organs – notably the heart–are under automatic control. Most of the time this is true of me, too, though I am under voluntary control as well. As a child, Joe had temper tantrums and would sometimes hold his breath until he turned a faint blue. His mother worried unnecessarily. Long before he got into any real trouble, automatic respiration would take over. He would start breathing whether he wanted to or not.
My automatic breathing control is in the medulla oblongata–the bulge where the spinal cord taps into the brain. It is an amazingly sensitive chemical detector. Laboring muscles burn oxygen rapidly and pour out waste carbon dioxide. As it accumulates, the blood becomes slightly acid. The respiratory control center detects- this instantly and orders me to work faster. Let the levels rise high enough, as when Joe does heavy exercise, and it orders deeper breathing as well one’s “second wind”.
Lying quietly in bed, Joe needs about nine liters of air a minute, sitting up requires 18; walking 27; running 56. Since Joe is a desk · worker, he has no large oxygen demands. Normally, he breathes about 16 times a minute–half a liter of air each time. (This only partially inflates me. I can hold eight times as much.) Even so, not all of that half-liter breath reaches me; one third of it shuffles aimlessly in and out of the windpipe and other air passages.
I like my air just about as moist and warm as that in a tropical swamp. Producing this very special air in the space of a few centimeters is quite a trick. The same tear glands that bathe Joe’s eyes, plus other moisture-secreting glands in his nose and throat produce as much as half a liter of day to humidify my air. Surface blood vessels along the same route – wide open on cold days, closed on warm days – take care of the heating job.
There is an almost endless list of things that can cause me trouble. Each day, Joe breathes in a variety of bacteria and viruses. Lysozyme in the nose and throat, a powerful microbe slayer, destroys most of these. And these that slip into my dark, warm, moist passages-a microbial happy hunting ground–I can usually handle. Phagocytes patrol my passages and simply wrap them- selves around invaders and eat them.
Dirty air, of course, is my biggest challenge. Other organs lead sheltered, protected lives but for all practical purposes I am outside Joe’s body–exposed to environmental hazards and contaminants. I am really quite delicate, and it is a wonder I am able to survive at all, having to deal with such things as sulphur dioxide, benzopyrene, lead, and nitrogen dioxide. Since some of them actually melt nylon stockings, you can guess what they do to me.
My air-cleaning process such as it is–begins with hairs in the nose, which trap large dust particles. Sticky mucus in nose, throat and bronchial passages acts as fly-paper to trap finer particles. But the real cleaning job falls to the cilia. These are microscopic hairs tens of millions of them–along my air passages. They wave back and forth like wheat in the wind, about 12-times a second. Their upward thrust sweeps mucus from lower passages to the throat, where it can be swallowed.
If Joe could watch my cilia under a microscope, he would see that if cigarette smoke or badly contaminated air is blown on them, the wind-in-the-wheat field action stops. A temporary paralysis sets in. Let this irritation continue lag enough and the cilia wither and die, never to be replaced.
After 30 years of smoking, Joe has lost most of his cilia, and mucus secreting membranes in his air passages have thickened to three times normal size. Joe does not know it, but he is in actual danger of drowning. If enough mucus drops down into my air sacs, it halts breathing just as effectively as a lungful of water. One thing saves Joe from this: his noisy inefficient smoker’s cough; which has replaced the quiet efficiency of the cilia. Joe might remember that it is the only cleaning method left to me–and be cautious about taking cough-suppressing drugs.
A large part of the time, Joe is asking me to breathe real garbage. Some of the particles clog my smaller passages, and some scar my tissues. The fragile walls of my alveoli lose elasticity. I do not collapse the way they should when I exhale. (Thus it is possible to breathe in but not out.) Carbon dioxide is trapped in them and they can no longer contribute oxygen to the blood or extract waste carbon dioxide. The result is emphysema-a fearsome trial in which each breath represents a fight for survival.
Although Joe does not know it, this has already happened to a few million of my alveoli. Since Joe has about eight times the lung capacity he needs for deskwork, he still has plenty of reserve. But lately he has noticed that even a small amount of exertion brings on breathlessness. I am warning him.
Joe should heed the old medical saying, “If you are aware that you have lungs, you are already in trouble,” and take a little better care of me. In the main, this means giving me better air to breathe. The big thing, of course, would be to give up smoking. Short of this, them are other things he can do. There is a small, reasonably priced machine, which circulates room air through a thin bed of activated carbon–the stuff used in gas masks-and cleanses this air of chemicals deadly to my tissues. One in Joe’s bedroom would give me some eight hours of protection, and another in his office would provide eight more.
A little more exercise and more sensible eating would be in order. Any general body exercise–climbing stairs, walking, jogging sports-forces me to breathe more deeply, which is all to the good. And there are exercises for me alone. Ordinarily, the best breathing is deep breathing–more air at a slower pace. Joe could practice abdominal breathing, the way babies and opera singers do: not by inflating the manly chest, but by dropping the diaphragm down. Then air is sucked into even my deepest alveoli.
Joe could also give me a housecleaning a few times each day. He thinks that with a normal exhalation I am empty. By no means. Let him blow out all the air he can via his mouth. Then if he will purse his lips, he can do quite a lot more blowing. If he does this while smoking, he will see something that should give him pause: smoke trailing out through his pursed lips that would normally be left in me to stagnate.
It all adds up to this: Most of my neighbor organs can absorb an enormous amount of abuse without complaint. I cannot. Nature has not equipped me with all the defenses I really need in today’s world. That is why a variety of lung diseases have reached epidemic proportions.
Boss Joe, take heed!
From Ratcliff, J.D. (1986). I Am Joe’s Body. New York, New York: Berkley/Reader’s Digest.