where does right atrium pump blood when it contracts
Atrium (heart) The atrium is the upper chamber in which blood enters the heart. There are two atria in the human heart, which receive blood - the left atrium from the lungs, and the right atrium from the venous circulation. The atria receive blood, and when the heart muscle contracts, pump blood to the ventricles. All animals with a closed circulatory system include at least one atrium / auricle (humans have two atria).
Tricuspid valve The tricuspid valve, or right atrioventricular valve, is on the right dorsal side of the mammalian heart, between the right atrium and the right ventricle. The function of the valve is to prevent back flow of blood from the right ventricle into the right atrium.