Capillary glucose (such as in blood glucose monitoring), hemoglobin, pH and lactate Capillary blood sampling is generally performed by creating a small cut using a blood lancet, followed by sampling by capillary action on the cut with a test strip or small pipe. Contrary to a popular misconception, William Harvey did not explicitly predict the existence of capillaries, but he clearly saw the need for some sort of connection between the arterial and venous systems. He wrote, "…the blood doth enter into every member through the arteries, and does return by the veins, and that the veins are the vessels and
Hemodynamics forces (e.g., during standing), and valves in veins, breathing, and pumping from contraction of skeletal muscles also influence blood pressure in veins. The relationship between pressure, flow, and resistance is expressed in the following equation: When applied to the circulatory system, we get: where A simplified form of this equation assumes right atrial pressure is approximately 0: The ideal blood pressure in the brachial artery, where standard blood pressure cuffs measure pressure, is <120/80 mmHg. Other major arteries have similar levels of blood pressure recordings indicating very low disparities among major arteries. In the innominate artery, the average reading is