MEDICAL APPARATUS FOR MONITORING BLOOD PRESSURE, HEART BEAT, AND THE LIKE COMPRISING A SYSTEM HAVING INTERCHANGEABLE BINAURAL AND MONAURAL STETHOSCOPE HEAD SETS, TUBING, VALVES, AND A PLURALITY OF CHESTPIECES INCLUDING A SPHYGMOMANOMETER AND A PRECORDIAL CHESTPIECE TOGETHER WITH QUICK DISCONNECT JUNCTIONS WITH THE VARIOUS COMPONENTS OPERATIVELY INTERCONNECTED