18 Feb 2016 | 258,249 Views. You may not even associate this with your health, yet it can make a life or death difference. Ignore or defy it, and your risk of death before your 65th birthday jumps 25 percent. Here's the big takeaway message to tell your body for health and longevity.
1 Veins have valves which maintain the unidirectional flow of blood, even against gravity. 2  Since the venous pressure is low (7 mm Hg) the valves are of utmost value in the venous return. However, the valves are absent in: 3  The veins of less than 2 mm diameter.  The venae cavae.
How the heart valves work. 1  The mitral valve and tricuspid valve, which control blood flow from the atria to the ventricles. 2  The aortic valve and pulmonary valve, which control blood flow out of the ventricles.ow the heart valves work. 1  The mitral valve and tricuspid valve, which control blood flow from the atria to the ventricles. 2  The aortic valve and pulmonary valve, which control blood flow out of the ventricles.