3 More Facts About The Lungs

In an earlier post, I presented “6 Interesting Facts About The Respiratory System.” In this post, I’d like to present 3 more interesting facts about the respiratory system. Ready! Here we go!

1. Your airways are unique

Like fingerprints, every set of lungs is unique.1 From the trachea, they branch into two bronchi. One leads to the right lung and the other to the left lung. Bronchi branch out into smaller and smaller airways. The smallest ones are called bronchioles.

If you look at a diagram of a set of airways, they sort of look like an upside down tree with all its branches. When you plant a tree, you have no way to predict where branches will develop. This is the same as the airways inside your lungs. How they branch out is different from one person to the next.

COPD is often referred to as a heterogeneous disease. This means that it affects each of us in different ways. So, since all our airways are unique, this might help explain this heterogeneous nature of COPD.

2. You have a lot of alveoli

The smallest bronchioles are called respiratory bronchioles.2 These are surrounded by small, grape-like clusters called alveoli. These are balloon-like structures that expand when you inhale and recoil to their natural shape when you exhale. This is where gas exchange occurs.

Alveoli are clustered this way to increase the surface area where oxygen can come into contact with capillary blood. So, let’s put this into perspective. In total, the average adult human has about 300 million alveoli. If you take all your alveoli and spread them out, you will come up with a surface area of 140 m2.2

That, my friends, is the size of a tennis court. That is a lot of surface area.

Okay, so let’s put this into COPD perspective. Throw in emphysema (that nasty disease) into a set of lungs. Emphysema destroys alveoli. So, now you spread alveoli out and you get less surface area. You might get half a tennis court. You might get an air hockey table. So, this kind of puts into perspective how emphysema can make you feel so short of breath.

3. Airway cells are tightly packed for good reason

All tissues of your body consist of cells. Every cell has a cell wall and a nucleus. Lining the walls of your airways are specialized cells. They are called ciliated pseudostratified columnar epithelium.3

Stratified means cells are lined up in different layers. Pseudo means they look stratified but really aren’t. Ciliated means they contain cilia for moving mucus to your upper airway. Epithelium simply means they are surface cells. They make up the surface of the airway walls.

Airway epithelial cells are actually neatly lined up. But, they just look stratified because they are so tightly squeezed together. Because they are squeezed so tight, their nuclei aren’t lined up in an orderly fashion. This gives the appearance of different layers.

So, have I bored you yet. Well, now we’re getting to the good stuff. What’s interesting here is: Why are they so tightly squeezed together? It’s another natural mechanism for keeping us healthy. It’s to prevent germs we inhale from getting in between cells and causing infections. And I think that’s pretty cool.

If you want to see a picture of what I just described, check out my post on our sister site, Asthma.net about the anatomy of airway walls.

Our bodies are all unique

Okay, so I officially succeeded at boring you. That’s okay. Sometimes I bore myself with all this new wisdom. Still, it’s neat to know. It’s neat how nature works. It’s neat how nature makes us all different. It’s neat how nature gives us so much surface area inside our chests. And it’s neat how nature works in such subtle ways to keep us healthy.

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