## blood pressure and atmospheric pressure

The normal atmospheric pressure is 760 mm of Hg. But the normal human blood pressure is around 120/80 mm only. In that case how equilibrium of our body is achieved? For any vessel to retain its original shape its inside pressure and outside pressure should remain equal. If the outside pressure exceeds the vessel will be crushed inward and if the inside one exceeds it will blow up. In the case of our body, assuming it as vessel, how the pressure of atmosphere which is nearly six times higher than the blood pressure inside, could not crush the body inward?
Are there any other inward forces make up for the rest in order to counteract the atmospheric pressure? Also why do we not feel the atmospheric pressure acting on our body surface at all?
 Recognitions: Science Advisor The blood pressure measurments are "relative pressure", meaning the figures that you state are above atmospheric pressure.

Mentor

## blood pressure and atmospheric pressure

760+120=880

Think about it: the measurement is taken with a pressure measuring device open to atmosphere.
 Does it mean that the actual blood pressure is 880 mm of Hg? In that case it means the actual blood pressure is 120 mm higher than that of the outside pressure.If so how balance is achieved? If there is no balancing mechanism, I should feel as if my blood is pushing my body from inside!
 Mechanical strength of blood vessels. Not everything gets crushed because of a pressure difference. Think of, a can of fizzy drink, a high pressure hose pipe, gas/water pipes, an aeroplane. All are pressure containers. So just like a waterpipe with high pressure water rushing through it doesn't explode (usually) neither do blood vessels. Note that if blood pressure get's too high, your blood vessels can break.
 Mentor 120 mm is not a lot of pressure for a hose like your blood vessels to hold.

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