Breathing – it happens automatically, keeps you alive, and no doubt you rarely think about it. But scientists do – they’re the pondering type – and that’s why they’ve figured out the answer to a niggling question about breathing control. They knew that sensors in the brain’s breathing centre – the retrotrapezoid nucleus (RN) – detect rising carbon dioxide (CO2) levels in the blood and trigger the lungs to inflate. They also knew that high CO2 causes acidity, which can damage tissues, especially the brain. Here was the niggle: to protect itself, the brain dilates its blood vessels to increase flow and wash out CO2, but in the RN this would be counterproductive, reducing the signal to breath. So, what happens there? It turns out that, unlike other blood vessels in the brain, those in the RN constrict in response to CO2, increasing the molecule’s concentration, ensuring its detection, and thus prompting a timely inhalation.
Written by Ruth Williams
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