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Voiceover: So the two categories[br]that we assign to emphysema,

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the centriacinar and the panacinar,

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they're basically referring to geography.

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It's like saying, my city's flooded,

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and is it contained to the[br]central streets, the main street,

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or is it everywhere?

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So basically, it's asking,[br]"Where is the emphysema?"

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So a little Latin review, we have "pan,"

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which means everywhere,

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and "centri," so "center."

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Now, what on earth is an "acinar?"

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And basically, that's a[br]geographical term too,

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and this is an "acinus."

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To orient ourselves, let's draw the lungs.

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We have the trachea here,[br]and the two big bronchi,

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so you have your lobe of lung[br]here, and lobe of lung here.

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The bronchi are kind of[br]like your tree trunks,

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and as they start to branch off like this,

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the smaller airways here[br]are called "bronchioles,"

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and that's basically the[br]level we're at right here.

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Here is our bronchiole,[br]and the rest of this branch

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that I've drawn, is just[br]the rest of the airway.

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So here, we have our alveoli cluster.

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So there are many many countless branches

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of acini in the lungs, but this[br]is what one would look like.

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So that tells us centriacinar[br]versus panacinar,

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we're talking about[br]where, in this, are we?

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So in this normal acinus that I've drawn,

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you can see the tightly,[br]little coiled structures here

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in the alveoli, and along the airways too.

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This elastic, coiled shape is possible

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because of our protein, elastin.

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Elastin is cleaved by elastase,

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which is this protein inhibitor,[br]which is good usually,

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because we want the tissue to turn over,

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old ones to be eaten up.

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And this whole system is[br]controlled by Alpha 1-antitrypsin,

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which is a compound made[br]in the liver, and it's job

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is to regulate the amount of elastase.

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So, by inhibiting the elastase,[br]it inhibits the elastin,

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the antitrypsin lets[br]there be more elastin.

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So whether we're going to[br]have centriacinar here,

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or panacinar destruction of elastin,

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fully depends on the pathophysiology

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of why is there so much elastase?

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Why is elastin getting destroyed?

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So first, let's take a[br]look at centriacinar.

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And this is what it looks like,[br]so I've draw the same acinus

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that we have up there,

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but because of the lack of elastin in it,

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there're fewer of the walls to begin with.

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And, whatever walls there[br]are left, it's because

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it's so floppy, that's why[br]it looks bigger like that,

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it just doesn't hold that nice shape.

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So this is what we call[br]"centriacinar distribution,"

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as you can see, geographically,

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it's earlier, it's not everywhere.

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Centriacinar is really[br]related to inflammation,

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which is the first[br]pathophysiology of emphysema.

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Now inflammation recruits neutrophils,

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these white blood cells[br]that flight inflammation

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everywhere in the body.

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But when they get to the[br]lungs, the neutrophils

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make elastase, that's[br]the whole culprit here.

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So it's too much elastase,[br]from too much inflammation.

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And the way we'd get that,[br]most commonly, is from smoking.

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So even though, when you[br]see somebody smoking,

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and the smoke rising out of there

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looks like just some sort of gas,

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it's actually made of millions[br]of tiny little particles,

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that enter the lungs.

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They're all foreign,[br]they're all irritating,

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and the lung acts like a[br]filter, these smoke particles

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are big enough to get[br]trapped pretty early on.

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They're not small enough[br]to get through the filter,

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all the way to the end of the acinus,

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so they kind of stay in this[br]central acinar distribution,

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which then makes sense,[br]that central acinar

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is related to smoking,

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and the inflammation you get from that.

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So if you look at the lungs as a whole,

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centriacinar is early on,

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and near the larger-caliber[br]airways, like the bronchioles.

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Now the next one, panacinar.

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So panacinar is usually[br]not induced by some sort

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of external factor;

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this problem arises[br]out of the body itself.

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Here we have Alpha[br]1-antitrypsin deficiency.

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Remember, we said up there,[br]this regulates the amount

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of elastase, namely to[br]tone it down a little bit.

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So without it, the elastase[br]is really unchecked;

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it just goes nuts, and[br]eats up all the elastin

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in the tissues, everywhere.

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See this problem[br][unintelligible] earlier or later

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in the lungs,

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because it's inherent in all[br]the tissues of the lungs.

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So everywhere the elastin's[br]getting chewed up,

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everywhere there's elastic tissue.

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Just as a side note, Alpha 1-antitrypsin

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is made in the liver,

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and in this disease,[br]when there's deficiency,

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that means something in the DNA,

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and the gene encoding for it,

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there's a mistake.

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So, all the misfolded protein[br]can't leave the liver,

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leading to liver disease.

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But when we come to the lungs,

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we see panacinar emphysema.