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ventilation perfusion coupling

Discussion in 'MCAT Study Question Q&A' started by Transformers, Aug 6, 2009.

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  1. Transformers

    Transformers 10+ Year Member

    Jul 12, 2007
    I was curious. I realize that if alveoli are poorly ventilated (low O2 and high CO2), arterioles constrict to shunt blood to better oxygenated areas and that high O2 and low CO2 in alveoli cause dilation of arterioles to allow for greater blood flow.

    I was curious about what signals cause bronchioles to dilate and constrict. For example, if tissues are highly metabolic and venous blood vessels are delivering more CO2 back to the alveoli, do bronchioles dilate to allow greater diffusion of CO2 out of the lungs? (thus, a signal such as epinephrine might trigger such effect on the bronchioles)...would this be correct? What other oxygen/CO2 conditions trigger constriction/dilation of bronchioles?

    Last edited: Aug 6, 2009
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  3. Charles_Carmichael

    Charles_Carmichael Moderator Emeritus 7+ Year Member

    May 10, 2008
    Are you confusing vasodilation with bronchodilation? It's just your second paragraph starts talking about bronchioles while your first one is talking about arterioles.

    There would be bronchodilation in response to sympathetic stimulation. For example, bronchodilators used to treat asthma, COPD, etc. include B2 (sympathetic adrenergic receptors) agonists such as albuterol, etc. I'm not entirely sure how much of an effect local metabolism has on bronchioles since local metabolism should affect what's in the blood stream (ie. inside blood vessels) rather than what's out of it.

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