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