Your blood pressure and breathing rate rise when you exercise and fall when you stop, so that the right amount of oxygen and nutrients are delivered to your muscles. The Belgian scientist Corneille Heymans (inset) won the Nobel Prize for Medicine 75 years ago for discovering a control mechanism for respiration – sensors in the carotid artery in your neck measure the pressure and oxygen content of blood and signal your brain to speed up or slow down heart beat and breathing. Earlier scientific drawings of the carotid region, like the one pictured, helped Heymans develop his theories. Since his 1938 award, many lives have been saved through our understanding of this reflex system and research continues today – for example, recent experiments on rats found that high blood pressure could be permanently reduced by interrupting the nerve connection between the carotid sensors and the brain.
Written by Mick Warwicker
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