What is an active site and what is its relationship to an enzyme? an active site in an enzyme is the area that breaks the bond in its substrate. E.g. a maltose molecule's glycocide bond is broken by the active site in a maltase enzyme.
The caffeine in a cup of coffee might help your small blood vessels work better. Credit: Â© jogyx / Fotolia. The caffeine in a cup of coffee might help your small blood vessels work better, according to research presented at the American Heart Association's Scientific Sessions 2013.
A morning cup of coffee stimulates the adrenal glands to release âfight-or-flightâ adrenal hormones. This raises your heartbeat, dilates your pupils, tightens the muscles, raises your blood pressure, slows blood flow to the stomach, and releases glucose into the bloodstream.