The first part of the film explains how the arteries work. An intertitle says 'Pulsations of the heart are felt in the arteries', and blood is shown moving through an artery. An intertitle says 'A beef artery shows elastic structure', and a hand is shown holding a cow artery , squeezing it and filling it with water. Next, a demonstration shows that elastic tubes like arteries absorb unevenness of flow whereas rigid tubes do not. An intertitle then says 'The pressure of the blood in arteries can be measured', and a doctor is seen taking a male patient's blood pressure. An illustration shows where the artery is in the arm and how the blood pressure machine works; pressure is increased until the flow of blood stops, and then pressure is reduced until blood begins to flow again. At this point, blood pressure is read. The next part of the film explains how veins work. A hand is seen holding a cow's vein and filling it with water. When this is done, water shoots back out of the vein, and an intertitle explains 'Valves keep the blood from flowing backward in the veins', and the valves are shown in detail.