We live in a society where researchers are constantly learning new things about the human body, and this is especially true of the respiratory system. Here are ten interesting things about the respiratory system you might now know.
1. Tiny hairs lining your airways act like escalators.
When foreign invaders enter your airway, they get trapped in sticky mucus secreted by goblet cells. Cells lining airways have small hair-like structures (about 100 per cell) called cilia that move back and forth and move microbe containing mucus to the upper airway, where they are swallowed and destroyed by stomach juices. This system is so effective that inhaled particles are usually removed within 24 hours. 1,2
2. Your nose is a filter, heater, and a humidifier.
The nose has small bone-like shelves called turbinates that project from the lateral wall of your nose. Turbinates are lined with lots of blood vessels, heat from which warms air passing by to body temperature. They are also lined with goblet cells that secrete mucus, and these help to humidify air as it passes by. Inhaled particles and microbes are trapped in the sticky mucus and moved to the back of your throat by the “escalator” to be swallowed, where gastric juices destroy them.1,2
3. Some movements of the respiratory tract are non-respiratory.
When most of us think of respiratory we think of movements, such as inhaling and exhaling, in order to move gasses into and out of our lungs. However, some movements are non-respiratory. Examples of non-respiratory movements are crying, laughing, sneezing and coughing. Coughing and sneezing, by the way, are natural mechanisms for keeping your lungs clear of foreign substances and invaders you might unknowingly inhale. 2
4. Some air never leaves your lungs.
You have a small amount of air, called residual volume, that always stays inside your lungs. This is important because it prevents your smaller airways and alveoli (small balloon-like air exchange units) from collapsing. It keeps them open just a little bit so that the next breath comes easier, sort of like a small balloon that has already been blown up once or twice. So, after you exhale, you can always push more are out of your lungs, although you can never consciously get it all out. At a minimum, about 1,200 ml of air remains in your lungs. This is a good thing.1
The following are interesting things about the respiratory system that you may not know, and your respiratory therapists, nurses, and doctors might not know either. Trust me, I know because I’ve grilled many of my coworkers.
5. Bronchial muscles are not even needed.
Researchers have tried to come up with a physiologic purpose for the smooth muscles wrapped around airways, and they have come up with nothing but flawed theories. They have now concluded, so it seems, that there is no physiological purpose for them, other than to become inflamed, spasm, and squeeze airways to cause asthma and COPD symptoms. 3
6. Your lungs are not sterile, even in health.
When I was in respiratory therapy school I was taught that, under normal healthy conditions, lungs are sterile, or germ-free. We were essentially lead to believe that our immune systems were immaculately effective at keeping germs out of airways, most of the time. Turns out this wisdom was flawed.
Dickson and company recently published reports where they claim this myth is based on 130-year-old research that found no bacteria in healthy lungs. However, after performing the same tests with modern technology, bacteria was found. Here is some of what they said:
- “The notion that the lungs are sterile is still frequently stated in textbooks, virtually always without citation.”
- “While the lungs have historically been considered sterile in health…, subsequent studies have since demonstrated that the lower respiratory tract is replete with diverse communities of bacteria both in health and in diseased states.”
They do not, however, know the significance of these colonizations. However, it might be fair to assume that they are norma flora, or microbes that normally live inside our bodies that do not cause disease.
Now you are armed with better wisdom. Or, as they say, useless facts. But no wisdom that makes us smarter is useless. This is especially true when you can use it to impress someone.