*1.Is the only source of energy in the cardiac circuit the heart? Or
does artiole smooth muscle actually inject energy into the system,
and result in systemic increases in the pressure available in the
closed circuit?
 2. I don't think vascular compliance ie expansion of the artery walls due to volume filling results in any active injections of
energy into the system..it should simply transfer the energy
available to push fluid to elastic energy in the connective tissue
of the artery walls. Is this correct?
 3. Does vessel compliance partly determine the pressure the heart has to inject into the system?
 4. What is the relationship between compliance and flow if there is one?*