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
Which? Which? Which? is a brand name used by the Consumers' Association, a registered charity (No. 296072) and company limited by guarantee (No. 580128), which is based in the United Kingdom. It exists to promote informed consumer choice in the purchase of goods and services by testing products, highlighting inferior products or services, raising awareness of consumer rights and offering independent advice. The association owns several businesses, including "Which? Financial Services Limited" ("Which? Mortgage Advisers"), "Which? Legal Limited" and "Which? Limited", which publishes the "Which?" magazine. The vast majority of the association's income comes from the profit it makes on its