How to Tell Crystal From Glass. Here are some quick tips on how to distinguish classic crystal from plain glass. 1  Hold up a glass to the light. 2  If the glass acts as a prism and you see a rainbow you are holding crystal. 3  If not, it is just plain glass. 4  When struck, crystal produces a musical ring.
Blood pressure is controlled by tiny muscles that line the inside of your blood vessels. These muscles allow your arteries to operate like soft rubber tubes, that expand with each beat of your heart. When these muscles throughout the vascular system [the arteries and veins that carry blood] expand, blood pressure drops.
The kidneys help to regulate the blood pressure by increasing (when blood pressure falls) or decreasing (when blood pressure rises) the blood volume, and also by the renin-angiotensin system described above.The kidney-fluid system is the main method of the long-term control of blood pressure.he arterial blood pressure is the force causing blood to flow through the arteries, into the capillaries, then back to the heart via the veins. The left ventricle contracts (systole), ejecting blood into the aorta, creating a pressure pulse.