eli5: If your leg gets amputated, how does your body know to not produce enough blood to replace what was lost?

Question

eli5: If your leg gets amputated, how does your body know to not produce enough blood to replace what was lost?

In: 2195

Answer 1

The kidneys sense blood pressure and try to keep that in a tight range, rather than the actual volume of blood. If pressure doesn’t drop in the remaining body (i.e. bleeding is kept to a minimum during the surgery), they barely register the change at all.