WASHINGTON, DC - JANUARY 20: U.S. President Donald Trump delivers his inaugural address on the West Front of the U.S. Capitol on January 20, 2017 in Washington, DC. In today's inauguration ceremony Donald J. Trump becomes the 45th president of the United States.
One-Way Valves in the Veins. One-way valves consist of two flaps (cusps or leaflets) with edges that meet. These valves help veins return blood to the heart. As blood moves toward the heart, it pushes the cusps open like a pair of one-way swinging doors (shown on the left).
exists and is an alternate of . Arteries do not have valves because the heart provides the pressure needed to send blood through the system. Veins have valves because venous pressure is often not great enough (as the blood must overcome gravity and other forces) to return the blood to the heart. <b>Arteries do not have valve</b><b>s</b> because the heart provides the pressure needed to send blood through the system. <b>Veins have valves</b> because venous pressure is often not great enough (as the blood must overcome gravity and other forces) to return the blood to the heart.