Several years ago a siege of bronchitis caused me to suffer with a severe cough that in turn resulted in sudden shortness of breath, gasping for air and likely my demise. Fortunately, a trip to the emergency room, a Medrol dosepack and two inhalers solved my problem. Since then I no longer take the simple act of breathing for granted.

I have developed an acute interest in anything related to the process of respiration and the associated anatomy. My research led to a number of facts I was unaware of or had forgotten. For example, I learned that absence of breath is the major way to certify or determine that someone is dead. In Renaissance times a feather would be placed on the lips to see if air was moving in and out of the lungs.

A human breathes about 20 times per minute, taking in 13 pints of air during that time. Breathing brings air (oxygen, nitrogen and traces of carbon dioxide) into the blood, which circulates it throughout the body. Air then passes through the larynx and trachea, where it is directed to the chest cavity. In the chest, the trachea splits into two bronchi, which lead to the lungs. Each lung consists of more than 100,000 small airways, more than 200 million alveoli, and has a surface area greater than that of a tennis court. Oxygen passes into the alveoli and diffuses through capillaries into the bloodstream, where red blood cells carry it to all parts of the body. At the same time, blood from the veins releases carbon dioxide into the alveoli, and it is expelled. Everything inhalable — from tobacco smoke to indoor and outdoor air pollutants, vapors to medications directly delivered to the lungs — has an effect on the the lung itself, and, if entering the bloodstream, other organs.

Breathing through the nose has a number of advantages. It acts as a filter and retains particles in the air, such as pollen. The nose also adds moisture to the air to prevent dryness in the lungs and bronchial tubes, and it warms cold air to body temperature before it reaches the lungs.

I was not aware that the nose produces nitric oxide, which improves the lungs’ ability to absorb oxygen. Nitric oxide enhances the ability to transport oxygen throughout the body, including inside the heart, and relaxes vascular smooth muscle, which allows blood vessels to dilate. Moreover, nitric oxide has antifungal, antiviral, antiparastic and antibacterial properties and helps the immune system fight off infections.

The average person breathes around 30,000 times during a 24-hour period. As newborns we draw our first breaths automatically, perhaps 40 times per minute, and it slows to closer to half that rate as we age. Fortunately we are hardwired to continue this labor reflexively, even in our sleep.

The effort of breathing consumes roughly 3 percent of our metabolic energy at rest, all in order to pull the equivalent volume of air the size of a grapefruit into our lungs. This process traps trillions of air molecules within our chests like fish in a net. Only a few of them, the oxygens, are what we are after. An average adult uses nearly 2 pounds of them every day, and this particular breath will help to keep us alive for the next few minutes. Your lungs are not the only route that oxygen takes to your blood, however. You also breathe a little through your eyes. So vital are these oxygen particles that the cells in the transparent surfaces of your eyes absorb them directly from the atmosphere to supplement the meager supply that your blood vessels send to them, as do many of the cells of your skin.

Unlike eating or drinking, you have to inhale oxygen continuously because, apart from the inflatable bags of your lungs, you can’t safely hold much of it inside of you. Even if you could purify and compress a lot of it into some internal storage space, you wouldn’t want to. Left unguarded within your body, oxygen can attack and damage your cells, and it is toxic in high doses. According to Curt Stager, in his book titled “Your Atomic Self: The Invisible Elements that Connect You to Everything Else in the Universe,” "Oxygen levels must be consumed in controlled sips, using it immediately and efficiently, and then take more from the sea of atoms that surrounds you."

Max Sherman is a medical writer and pharmacist retired from the medical device industry. can be reached by email at maxsherman339@gmail.com.