The body has mechanisms to alter or maintain blood pressure and blood flow. There are sensors that sense blood pressure in the walls of the arteries... My WebMD Sign In, Sign Up
Perhaps while we're not watching, the denizens of Dark Shadows carry-on, caught in another inter-dimensional wing of Collinwood. If you peer out the corner of your eye, you may catch a glimmer of this shadowy activity, perhaps in Dark Shadows Collection 14, or Dark Shadows Collection 22.
Clubs and amusement parks use special black light paint that glows different colors. You can also buy fluorescent black light bubbles, invisible black light ink, fluorescent black light carpet and even fluorescent black light hair gel. Ordinary highlighters work well as black light pens..