B - full version without watermark 720x576 (check terms and conditions at The version with watermark is for free to embed. Blood pressure is the pressure exerted by circulating blood on the walls of blood vessels. The pressure of the circulating blood decreases as it moves away from the heart through arteries and capillaries, and toward the heart through veins. When unqualified, the term blood pressure usually refers to brachial arterial pressure: that is, in the major blood vessel of the upper left or right arm that takes blood away from the heart.