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.
This is called maintaining homeostasis. The hypothalamus also maintains homeostasis in lots of other ways, such as by controlling your blood pressure. The hypothalamus also controls many of your hormones. It does this by being a sort of gatekeeper for other glands that release hormones. When your hypothalamus senses a change in your body, it will tell the right gland how to help correct that change.