MEDICAL PHYSIOLOGY

Detailed explanation-1: -The upper chambers, the right and left atria, receive incoming blood. The lower chambers, the more muscular right and left ventricles, pump blood out of the heart.

Detailed explanation-2: -There are four chambers: the left atrium and right atrium (upper chambers), and the left ventricle and right ventricle (lower chambers).

Detailed explanation-3: -The atrium was formerly called the ‘auricle’. That term is still used to describe this chamber in some other animals, such as the Mollusca. They have thicker muscular walls than the atria do.

Detailed explanation-4: -The upper chambers of the heart are called atria which always receive blood.