Unrelated to topic but I was in hospital recently and nurses came around to do vital,blood pressure oxygen temperature.i was having a high blood pressure. Often I lay with crossed legs but a nurse told me to uncross my legs and blood pressure went down. Why why cross legs increase blood pressure ?
I’d assume because one leg will inevitably be compressing the other, including arteries and veins?
Yes but they are measuring on your arm…
The whole thing is a circuit so increased pressure in one place means increased pressure everywhere in the circuit.
The pressure in your arm is not unrelated to or disconnected from the pressure in your legs. They are directly correlated. If the pressure in your legs goes up, so will the pressure in your arm, it’s the same system. The pressure in the entire system is what the arm measurement is supposed to show, that’s why they’re taking it. They usually don’t care about your arm specifically, they are trying to understand the whole system, including the pressure in your legs, which will be reflected in that same arm measurement. That’s the whole point, otherwise it wouldn’t be a good measurement.
Your blood vessels are a closed system. Imagine I fill a garden hose with water and cap it off at both ends, then kink the hose somewhere. Pressure will rise because it’s a closed system. It doesn’t matter if I kink it at one end or the other. Overall pressure will rise because I’ve removed some space somewhere.
Fill a rubber glove with water and tie the opening, now squeeze three of the fingers and observe what happens with the remaining ones
The cardiovascular system is effectively a very long bag of liquid, if you compress one area it can no longer hold the same volume of blood, that blood needs to go somewhere else, which increases the pressure in the other areas