During venipuncture (taking blood test) a nurse will wrap a rubber band around your arm to prevent blood from squirting thru the opening created by a needle. 

  Remember, your "blood pressure" (120/80 or so) is a real pressure inside your cardiovascular system.  It will make your blood squirt out whenever there is an opening.  Sometimes, when an unexperienced medical student takes a blood test and forgets to apply a tourniquet, the blood may shoot across the room, a very frightening experience for the patient and the medical student.

Did You Know That...

Colds are caused by over 100 different viruses.  For this reason, it is much more difficult to find a vaccine for a cold, than it is for a flu.