Ventilation - Perfusion Coupling

[lalajane]

After reading the same 5 paragraphs at least a dozen times, and retyping my notes a dozen times more, I'm crying "uncle" and asking for help. I've spent over 2 hours trying to grasp this concept, and I have soooo much ground to cover that I'm going to have to skip it and move on.

I understand that there must be a close match between ventilation and and perfusion for gas exchange to be efficient, but things get a bit foggy after that. "In alveoli where ventilation is inadequate, PO2 is inadequate. As a result the terminal arterioles constrict and blood is redirected to respiratory areas where PO2 is is high and oxygen pickup may be more efficient."

Is that telling me that the low ventilation is CAUSING the low the PO2? Or is it telling me that...oh jee, I've interpreted, misinterpreted, and reinterpreted this section so many times that I'm no longer sure if it's talking about gas exchange in the lungs or shopping for new shoes at the mall.

I've hunted and hunted for a video but I can't find much on this specific topic. Can anybody explain this (in basic 6th grade term)s in a way I might be better able to 'see' it?

Thanks so much for any insight anyone can offer.
La

[lalajane]

Thanks anyway. The exam is in an hour and I still don't "get it," but I'll just have to hope for the best!

[JackBean]

yes, I think you're correct. Since there is low ventilation, the oxygen is bound in blood, but no new one is delivered and thus there is low level of oxygen