Part of the show Naked Science Q&A and the Science of Happiness
Peter in Essex asked:
If someone has an amputation, do they get high blood pressure because there's less body space for the blood to move around in?
What we usually find is that they have lower blood pressure, paradoxically. If you lose, say, a leg, then there's less blood that needs to be pumped out of the heart and into the main blood vessels in order to get it around the body. You obviously have a big chunk of your body missing and it doesn't need any blood, and so your heart is doing less work. As a result, your blood pressure tends to drop a little bit. If you have people who've lost both their legs, they often have lower blood pressure because they've got fewer areas of tissue that need to be reached by the blood and so the average blood pressure in the vessels is lower.