What Your Doctor May Not Tell You About Hypertension The Revolutionary Nutrition and Lifestyle Prog

Just behind the endothelium, inside the artery wall, lies the media, a layer of smooth muscle cells that contracts and relaxes on demand. The media squeezes the artery passageway to make it narrower, and relaxes the pressure to let it widen. It does this at the command of the endothelium, which constantly monitors the environment, checking out the blood pressure and other factors. When something isn't quite right, the endothelium sends out certain hormones and mediators to set things straight. For example, if the blood pressure is too high, the endothelium may release nitric oxide (NO for short). The NO tells the media to relax. When the media stops squeezing, the artery gets a little bit wider and the blood pressure falls to a safer level. On the other hand, if the endothelium notices that the blood pressure has dropped too low, it can release various contracting substances that order the media to constrict, thus raising the blood pressure. In addition to the contraction and dilation of blood vessels, the endothelium helps to control the function of the platelets, clotting elements in the blood. It also dictates the thickness and thinness of the blood, how white blood cells stick to the artery walls, the inflammatory process, the growth, thickness, and stiffness of the vascular muscle, and other important factors. Another important job of the endothelium is to help control oxidative stress. Oxidative stress is akin to biochemical thievery. Electrically unbalanced molecules in the body snatch electrons from other substances in order to balance themselves. This may make the thieving molecules "feel better," but the molecules that were "mugged" may not be able to function properly anymore, leading to weakness or destruction of body cells and tissues. The body manufactures antioxidants to prevent (or at least control) this kind of damage, and we also absorb various antioxidants from our food. Often, however, the thieving molecules are too much for the body to handle, and we suffer from oxidative stress that can damage the endothelium and encourage hypertension. In short, the thin layer of cells lining the inside of the arteries acts like a monitoring and correcting station, constantly working to ensure that the blood flows and behaves properly.