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.
Brain stem. The brain stem controls your lungs and heart and blood pressure. It sits at the top of the spine and receives messages from the rest of the body. In some ways this is the most important part of the brain because it keeps you alive.halamus. There are lots of interesting things that go on in the very middle of the brain, which is made of smaller parts known as the limbic system. The hypothalamus and pituitary gland control things like your body temperature, how fast you grow and tells you when you are thirsty.