Atrium (heart) 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 that term is still used to describe this chamber in, for example, the "Mollusca", but in humans that name is
Hypoplastic right heart syndrome Expression of these genes expression is regulated by various processes, including transcription and growth factors, as well as proteins like fibrillin, Wnt, BMP2, BMP 4, BMP5, BMP7, which aid in different heart development features like the valves and septum, and other substances, such as retinoid and folic acid.[5] Crucial steps in heart formation are development of the ventricles and atrium formation, as well as septation and valve formation. Any disturbances of such processes may lead to various congenital heart diseases and defects that could be initiated by various genetic, epigenetic or environmental factors. The most common heart malformations from genetic