Lungs

The thing about lungs—and most of our health for that matter—is that when they’re working well, we barely notice them. It’s only when they’re threatened by something like a global respiratory pandemic that we start to notice just how talented these organs actually are.

Lungs are responsible for bringing in oxygen, which our blood ferries off to our cells to convert into energy. They take out some of the trash, too. As our cells make their own fuel, they spit out carbon dioxide. Our blood carries that gas back to the lungs, where we exhale it out without a second thought. Without this ability, the acidity of our bodies would increase rapidly, which would damage our organs and could ultimately be fatal—just like it would if we didn’t have oxygen.

And yet, for organs with a job that necessitates vital consistency, lungs are also the internal organ with the single most exposure to the perils of the outside world. This makes them exceedingly difficult to transplant; only about 15% of all donated lungs can actually be used for recipients because of the damage they can acquire through death (humans tend to aspirate as part of the dying process, for example) or through living (smoking and air pollution aren’t great for them either).

If anything, Covid-19 has made it even clearer that our lungs are precious. Although they can temporarily be replaced with ventilators, nothing on Earth quite measures up to their ability to fill our cells with what they need and toss what they don’t. Let’s take a deep breath and explore these fascinating organs.

5: The number of spongy lobes your lungs are made of (three on the right lung and two on the left, so your heart can snuggle in)

480 million: Number of air sacs, called alveoli, in one set of lungs

~2,100 square feet (~195 square meters): Surface area all the alveoli within your lungs can cover—think a singles tennis court

7: Number of seconds it takes for any inhaled substances (nicotine, pollution, etc) to reach the brain

1.5 pints (750 cubic centimeters): Lung capacity of the average man (for women, it’s around 0.8 pints or 393 cc)

6 minutes: Time actor Tom Cruise can allegedly hold his breath, after training for an underwater scene in Mission: Impossible – Rogue Nation

11 minutes, 54 seconds: Time Branko Petrović, a Serbian diver, held his breath underwater (using static apnea rules—there are several different types of breath holding types) to set a world record in 2014

Reader, it’s not pretty.

The problem isn’t so much how Covid-19 damages the lungs, but rather how the body reacts to the infection. One aspect of this overreaction comes from macrophages, which patrol the lungs looking for trouble and are kicked into high gear when SARS-CoV-2 enters the cells that make up the alveoli, says Matthew Woodruff, an immunology researcher at Emory University. These cells are part of the innate immune system’s fast but more generalized response to an infection. Such an approach sacrifices specificity; rather than targeting the virus, these cells simply cause a massive inflammatory scorched earth response, which can lead to fluid in the lungs that inhibits the alveoli from completing their usual gas exchange. This pneumonia can lead to acute respiratory distress syndrome, or ARDS, which requires treatment with a ventilator and has about a 50% lethality rate.

Covid-19 can be severe in people of all ages (the above photo is of an infected lung from a patient in her 20s who ultimately needed a double-lung transplant), but it’s most deadly in older adults. Even the healthiest older adults are at a natural disadvantage because of all their time on Earth, explains Candace Brown, a professor of gerontology at the University of North Carolina, Charlotte. The interstitial muscles around the rib cage and diaphragm are weaker, making it already harder to breathe, and if pre-existing conditions like COPD may already be straining the respiratory system, that’s not a great outlook.

But Covid-19 is not content to pose a threat to just the respiratory system—the novel coronavirus has turned its attention to plenty of other parts of the body. It can damage the heart and blood vessels, causing deadly blood clots or strokes. It can damage the intestines, causing dehydrating diarrhea. It can even cause neurological symptoms, ranging from mild confusion and brain fog to seizures in the sickest patients.

“What this virus does is it starts as a viral infection and becomes a more global disturbance to the immune system and blood vessels—and what kills is exactly that. Our hypothesis is that Covid-19 begins as a respiratory virus and kills as a cardiovascular virus.”

—Mandeep Mehra, professor of medicine at Harvard Medical School, as told to the Washington Post in May 2020

In 2015, the World Health Organization reported that 92% of the world’s population was breathing unhealthy air, which contains more than 10 micrograms of particles per cubic meter. A rare bright spot of the global pandemic is that lockdowns have kept people out of cars, decreasing the total amount of global air pollution in the past few months.

360 million years ago: Early land-dwelling creatures develop lungs.

2600 BC: Chinese physicians identify a condition that causes “noisy breathing.”

400 BC: Greek physician Hippocrates coins the term “asthma,” and notices that asthma attacks seem to be related to the sufferer’s environment.

50 AD: Roman scientist Pliny the Elder suggests that drinking a wild horse’s blood or boiled donkey milk could treat asthma. He was wrong and also gross.

1500s: Italian physicians hypothesize that the lungs’ purpose is to cool the air surrounding the heart, which would counteract anger (good thought!) and that they could convert air into energy (less good thought!).

1878: German physicians note tumors in the lungs, but consider it an extremely rare condition.

1930s: Lung cancer cases skyrocket globally. Scientists hypothesize that environmental factors like pollution are to blame.

1950s: Scientists start to treat asthma with metered doses of epinephrine, a precursor to modern inhalers.

1963: American physician James D. Hardy performs the first lung transplant; the patient survives for 18 days after the procedure.

1969: Scientists outline how cigarette smoking is to blame for much of the rise in lung cancers.

1981: The use of the immunosuppressant cyclosporine dramatically increases survival rates after lung transplants.

2018: American scientists grow lungs in a lab and transplant them into pigs, which were euthanized two months after the procedure; lab-grown lungs could ease the wait time for those waiting for a transplant, but this work isn’t ready for clinical trials just yet.

You’ve probably heard that deep breathing can help you relax, but did you know that scientists have actually seen it work (in mice)? In 2017, researchers from Stanford published work showing that by snipping out a select group of neurons responsible for arousal, mice were unable to become stressed, and their breathing stayed deep, slow, and steady.

It’s one thing to say that lungs take oxygen in and expel carbon dioxide, and another thing to show how it works. This will happen up to 60 times in your own body during the time it takes to watch Emma Bryce’s three-minute animated video for TED Ed.

Your lungs can’t get all the credit for keeping you alive. They’d be useless without the muscles that surround them. In reptiles, breathing occurs with the help of muscles lining the rib cage that squeeze and relax the lungs. In mammals, it comes with the help of a diaphragm. This tiny, involuntary muscle sits at the base of the lungs; we flex it to inhale, and relax it to exhale. This little muscle allows mammals to take more powerful breaths, which may have ultimately contributed to our evolution to be warm-blooded—an energetically expensive way to go through life. Writing for the New York Times, Carl Zimmer will take you deeper into diaphragm.

Consultants are only as healthy as their clients, so when a global recession hits, how do consultants keep their heads above water? If they’re smart, they’ll present themselves as essential pandemic-fighting experts and adapt as quickly as they can to a new way of meeting, advising, and networking.

But can they do all that and more without their trusty whiteboards?

This week’s field guide shows us what we can learn from how the consulting industry is coping with the ultimate challenge.