Blood Pressure (BP) is the pressure exerted by the blood against the walls of the blood vessels, especially the arteries. It varies with the strength of the heartbeat, the elasticity of the arterial walls, the volume and viscosity of the blood, and a person’s health, age, and physical condition.
The importance of blood pressure is that it effectively provides a store of energy, generated by the heart, available to cause blood to flow through the working tissues. It is actually the flow of blood, providing oxygen and nutrients and removing waste products including carbon dioxide, which is really the important factor, but without pressure there would be no flow. Humans, being upright bipedal animals, have a particular problem in supplying blood to all parts of the body. Due just to gravity, pressure in arteries supplying the head is about 100mm Hg less than that in arteries in the feet. The fact that the brain must have an adequate arterial pressure places a limitation on the range of effective pressures in the upright person.
