{HEAD ~ The valves} regulate {TAIL ~ fluid flow} to the second chamber in accordance with electrical signals from the heart 
regulate
{ HEAD ~ The valves } regulate { TAIL ~ fluid flow } to the second chamber in accordance with electrical signals from the heart
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH