1530s, a running (usually at full speed), a course (especially of the sun, etc., across the sky), from Middle French carriere road, racecourse (16c.), from Old ProvenÃ§al or Italian carriera, from Vulgar Latin *(via) cararia carriage (road), track for wheeled vehicles, from Latin carrus chariot (see car).
Noun. 1. tricuspid valve-valve with three cusps; situated between the right atrium and the right ventricle; allows blood to pass from atrium to ventricle and closes to prevent backflow when the ventricle contracts. right atrioventricular valve.
Veins have valves to prevent blood from flowing backwards and pooling, whereas arteries pump blood at higher pressures, which naturally prevents backflow.