Why bronchial circ. dumps deoxygenated blood in2 L. atrium?

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phuturephysician
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Why bronchial circ. dumps deoxygenated blood in2 L. atrium?

Post by phuturephysician » Thu Jan 29, 2009 8:09 pm

Now that I have your attention, let me proceed. I have searched extensively for this answer and I am having no luck.

Why does the bronchial circulation dump deoxygenated blood into the left atrium?

Thanks. Hope you can help.

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mith
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Post by mith » Thu Jan 29, 2009 8:45 pm

what do you mean why? that's how the system works.
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Re: Why bronchial circ. dumps deoxygenated blood in2 L. atrium?

Post by phuturephysician » Thu Jan 29, 2009 10:29 pm

Deoxygenated blood is being pumped into the left atrium which contains oxygenated blood. Mixing deoxygenated blood with oxygenated blood doesn't seem logical. I know that this amount of deoxygenated blood from the bronchial circulation is a small portion of the total systemic return, but I want to know why this occurs.

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mith
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Post by mith » Fri Jan 30, 2009 7:02 am

You're not talking about the human heart are you?
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Post by miloshic » Fri Jan 30, 2009 2:16 pm

In human heart, oxygenated blood goes into left atrium by vena pulmonalis, but deoxygenated blood comes into R atrium, then goes into R ventricle, and finally leaves heart going through arteria pulmonalis.
In Chondrychthyes and Osteichthyes(fishes), for example, there is no oxygenated blood going through their heart. In Amphibians, there are two atriums, but one ventricle, but still oxygenated blod goes into left, and deoxygenated into right atrium.
Reptiles - only crocodiles have, just like Aves(birds) and Mammalia, two atriums, and two ventricles. And again, oxygenated blood goes into left atrium, deoxygenated into right atrium.
So, I don't know where you found that incorrect information :)

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Re: Why bronchial circ. dumps deoxygenated blood in2 L. atrium?

Post by phuturephysician » Fri Jan 30, 2009 6:42 pm

Yes, this is the human heart. Bronchial circulation (feeding the lungs themselves) does indeed dump deoxygenated blood into the left atrium. I know that this is not a significant issue, it just makes me curious. I have found no real answers to explain this.

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Post by mith » Sat Jan 31, 2009 12:06 am

aaah, I see what you mean now, my apologies for not reading closely.
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Post by mith » Sat Jan 31, 2009 4:04 am

I think I'd say that it's because the lung system evolved before the septum evolved in the heart separating it. In the case of the frog, everything from the lung just gets dumped into the atria.
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Re: Why bronchial circ. dumps deoxygenated blood in2 L. atrium?

Post by phuturephysician » Sun Feb 01, 2009 8:47 pm

Mith, I've explored that option. There are some that believe that it is a remnant of the ductus arteriosus, but animals like opossums never have an ductus arteriosus and have the same setup for venous return...

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