What term refers to one of the heart's two upper chambers?

The term that refers to one of the heart's two upper chambers is "atrium." The heart is divided into four chambers: two atria (the upper chambers) and two ventricles (the lower chambers). The atria receive blood coming into the heart; the right atrium collects deoxygenated blood from the body, while the left atrium collects oxygenated blood from the lungs. This fundamental structure is essential for the heart's function, as it helps facilitate the flow of blood through the heart and into the ventricles, which then pump the blood to the lungs and the rest of the body.

The other terms in the options refer to different anatomical features: "ventricle" refers to the heart's lower chambers, "aorta" is the main artery that carries oxygenated blood from the heart to the body, and "coronary" relates to the coronary arteries that supply blood to the heart muscle itself. Understanding these distinctions is crucial for comprehending the anatomy and physiology of the cardiovascular system.