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
Aonghus (given name) "Onnust", "Hungus". According to historian Alex Woolf, the early Gaelic form of the name, "Oengus", was borrowed from the British Pictish "Onuist", which appears in British as "Ungust". Woolf noted that these names are all derived from the Celtic "*Oinogustos". Linguist John Kneen derived this name from two Celtic elements the following way: "*Oino-gustos", meaning "one-choice". Woolf also stated that between about AD 350 and AD 660, the Insular Celtic dialects underwent changes which included the loss of the final syllables and unstressed vowels, which affected "*Oinogustos" thus: "*Oin<del>o</del>gust<del>os</del>". Aonghus (given name) Aonghas is a masculine given name in Irish