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
Given name by the parents at birth. In informal situations, given names are often used in a familiar and friendly manner. In more formal situations, a person's surname is more commonly used—unless a distinction needs to be made between people with the same surname. The idioms "on a first-name basis" and "being on first-name terms" refer to the familiarity inherent in addressing someone by their given name. By contrast, a surname (also known as a family name, last name, or "gentile" name), which is normally inherited, is typically shared with other members of one's immediate family. Regnal names and religious or monastic