Atrium (heart) of blood occurs. In birds, mammals, and some other reptiles (alligators in particular) the partitioning of both chambers is complete. Atrium (heart) The atrium is the upper chamber in which blood enters the heart. There are two atria in the human heart – the left atrium connected to the lungs, and the right atrium connected to the venous circulation. The atria receive blood, and when the heart muscle contracts they pump blood to the ventricles. All animals with a closed circulatory system have at least one atrium/auricle (humans have two atria). The atrium used to be called the "auricle", and
Artificial heart valve require replacement (but typically less in younger patients). There are three major types of mechanical valves – "caged-ball", "tilting-disk" and "bileaflet valve " – with many modifications on these designs. The first artificial heart valve was the caged-ball, which utilizes a metal cage to house a silicone elastomer ball. When blood pressure in the chamber of the heart exceeds that of the pressure on the outside of the chamber the ball is pushed against the cage and allows blood to flow. At the completion of the heart's contraction, the pressure inside the chamber drops and is lower than beyond the