Organ of the Week

October 22, 2017 Medicine Comments (0) 533

The Lung

I may have been a little overwrought. By lauding the kidneys over the lungs in the last post, it’s possible I’ve done the body-bellows a disservice. So I resolve to address this. Today we shall examine reasons why the lungs, if not winning first place in the organ stakes, at least get a solid participation certificate.

There’s the obvious reason we like lungs. The whole oxygenation thing. Goes without saying, that’s cool. Plus the reverse removal of carbon dioxide. Sure. Great. We get it.

And yep, they do that half-assed, kind of flashy job with acid-base equilibrium (not to harp on, but nothing on the kidneys). Compensation, buffering, yada yada.

But, if we’re going to applaud the air-bags, then we should appreciate their more eclectic functions. After all, who wants to be known as a work-horse when you can be avant-garde?

Following are several of the lung’s more glamorous responsibilities:

  • Clot filter. When any muck, clot, or alien sort of material starts a-rambling through the vasculature, the immense pulmonary capillary network acts as a mostly impenetrable mesh, a fine sieve, a Gandalfian passage prevention kind of scenario. Which has raised the fairly recent question, in the light of our drunkenly lavish use of imaging, whether small pulmonary emboli are, in fact, a normal phenomenon. Lung lint, as they are amusingly alliteratively named. And, you may recall, lungs are a rich exuder of tPA and heparin like substances – helping melt away the coagulated clumps.
  • Lung as pawn. First line of immunological defence. Unlike the pawn though, the lungs have a staggering arsenal of protective mechanisms: a mucous blanket, a muco-ciliary escalator escorting inhaled foreign bodies back out the way they came, ravenous macrophages swallowing everything even slightly alien in a liquid eighties pac-man style,  and hundreds of other immunomodulatory functions.
  • A dizzying array of metabolic functions – molecules passing through the lungs have a high chance of being modified, activated, broken down, gender-switched and so on. I suspect we have hardly a clue as to the depths of activity going on in the dead of the thorax when we are not watching.
  • And, for the most surprising piece of new lung knowledge in 2017, some intrepid researchers from San Francisco discovered that the lungs produce up to 10 million platelets per hour, dwarfing the sluggish production line of the bone marrow. (Ed. note. One of the principle researchers was Mark Looney. I submit this without comment) (and who am I kidding. I am the editor. I was just trying to deflect such an infantile addition).

But let us move on from such dry physiological periphrastic discourse.

I have a story about lungs. It is not very pleasant. I have previously written about the German student exchange I endured when I was 16. My host family were not overly keen on having an exchange student, and they were quite fond of laughing at my expense. We were out to lunch one day just south of Nürnberg, and I was given a menu off which to order. My linguistic skills were lamentable. I recalled ordering an item like pinning a tail, blindfolded, to a donkey. It was lüngerl (or something similar). The family sniggered. I was wary. The dish came out, gravy brown and chewy, like a tyre stewed for 3 days in a steaming bog. I persevered. They laughed. Friends, lung is not a gourmet food.

Allegedly respiration was first described by an Arab physician, Ibn al-Nafis, in 1243. In the first half of the 16th century, the role of the lungs was thought to be to cool the heat and rage of the heart. In the next century, William Harvey, that most sensible of chaps, finally started to work out what the dickens was going on with them. The real Dickens speaks of our organ in Oliver Twist: “It opens the lungs, washes the countenance, exercises the eyes, and softens down the temper, said Mr. Bumble. So cry away.”

The lungs of vertebrates are evolutionary relations of the gas bladders of fish; in their most rudimentary form a simple outpouching of the oesophagus, allowing storage of a gulp of air in oxygen poor situations. Spiders have what is known as book lungs, and if I had to choose a type of lung, that is definitely what I would go for. Lungfish are ugly. There, I’ve said it.

A surprising number of songs have ‘lungs’ in the title. This includes Florence and the Machine’s Between Two Lungs and Megadeth’s Into the Lungs of Hell (if you were looking for a night lullaby for your children).

Now this is not a post about pathology and disease. We’d never get out of here if it were (and I can hear you straining to do so already). But as a last word, let us take a look at the lungs of some of the great writers. They were a pack of wheezing, dyspneic artists if ever there were, coughing their bloody expectorations delicately into their lace handkerchiefs. Proust died of asthma complicated by pneumonia, Keats, Katherine Mansfield, the Brontes, Chekhov and legions more succumbed to TB, Updike was carried off by lung cancer, and Evel Knievel’s life was (surprisingly, and really inappropriately placed here) terminated by idiopathic pulmonary fibrosis.

Thus, I end with an apology to the lungs, demonstrated this by this week’s award.

 

 

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