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Anatomy and Physiology: Gas Exchange

Posted by Courtney Smith on Fri, Jul 12, 2013 @ 03:41 PM

You know what’s awesome? Breathing.

The act of breathing is an involved one—multiple structures across multiple systems are involved, and yet, like sight, we take it somewhat for granted. I'd wager that we take all of our involuntary actions for granted. Breathing, blinking, smelling, tasting, our heart beating, our stomach digesting—most of us never stop to think how lucky we are that this stuff happens without a hitch. But I digress. Back to breathing!

Do me a quick favor: breathe in once, nice and deep, and then exhale.

Done? Okay, good. In the maybe two seconds it took for you to complete that action, your respiratory system was hard at work turning that deep breath into usable oxygen and nutrients for the rest of your body. Pretty wild, huh?

Let's take a look at gas exchange through the lens of our latest app, Anatomy & Physiology. (This section I am showing from the app is FREE to download to your Android, PC, or Mac.)


respiratory a&p bronchi lungs bronchioles respiratory tree alveoli gas exchange

The lungs (purple structures within the thoracic cage) are organs that act as the site for gas exchange. Each lung is conical in shape, very elastic, and spongy in texture. The left lung is divided into two lobes: upper and lower. The right lung is divided into three lobes: superior, middle, and inferior.

 

respiratory a&p bronchi lungs bronchioles respiratory tree alveoli gas exchange

Within each lung is a respiratory tree, comprised of the bronchi and its branching subdivisions—the primary bronchi, which branches into the secondary bronchi, which branches into the tertiary bronchi, which branches into the bronchioles. The bronchi deliver oxygen-rich air to the lungs, where gas exchange occurs in tiny air sacs called alveoli. Exhaled air (oxygen-poor and carbon dioxide–rich) go the reverse way—from the ends of the bronchioles and back up.

 

respiratory a&p bronchi lungs bronchioles respiratory tree alveoli gas exchange

Alveoli (shown in this image from the app) are tiny air sacs in the lungs—1.5 million per lung!—encased within capillary networks. Oxygen diffuses from the alveoli into the capillaries, which carry it out of the lungs and to the rest of the body; carbon dioxide diffuses into the alveoli and is then exhaled out of the body.



respiratory a&p bronchi lungs bronchioles respiratory tree alveoli gas exchange

The respiratory membrane (shown in this illustration from the app) is the barrier through which oxygen and carbon dioxide are exchanged.
 
 

respiratory a&p bronchi lungs bronchioles respiratory tree alveoli gas exchange

In pulmonary circulation—circulation between the heart and lungs—the vasculature are flipped. While normally arteries bring oxygenated blood away from the heart to the rest of the body, the pulmonary arteries take deoxygenated blood away from the heart to the lungs for replenishment. The pulmonary veins, likewise, return oxygenated blood to the heart from the lungs. 

 

respiratory a&p bronchi lungs bronchioles respiratory tree alveoli gas exchange

Wanna test what you've learned? The images here are from Anatomy and Physiology, an awesome app available for your Android, iPad, PC, Windows Tablet, or Mac. A free PC or Mac trial is available. Want to check it out before downloading a trial? Watch the 90-second preview.

 

Want to learn more?


Additional references:
Watch an interactive lecture on the structures of the respiratory system: http://youtu.be/NRT1hOqniZ0
Read about common lung diseases: http://www.nlm.nih.gov/medlineplus/lungdiseases.html

Topics: anatomy and physiology

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