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.
The four main valves in the heart are: 1  The two atrioventricular (AV) valves, the mitral valve (bicuspid valve), and the tricuspid valve, which are between the upper chambers (atria) and the lower chambers (ventricles). 2  The two semilunar (SL) valves, the aortic valve and the pulmonary valve, which are in the arteries leaving the heart. The mitral valve and the aortic valve are in the left heart; the tricuspid valve and the pulmonary valve are in the right heart. There are also the coronary sinus and the inferior vena cava valves.