What is the structure of the heart?

• A. A hollow, 4-chambered organ consisting of two atria and two ventricles
• B. A muscular, 3-chambered organ
• C. A gland-like organ with four lobes
• D. A solid, 2-chambered pump

Answer: (A)

The heart’s structure is defined by its hollow, muscular nature and its four chambers: two atria and two ventricles. The atria are the upper receiving chambers, and the ventricles are the lower pumping chambers. The right side handles blood returning from the body and sends it to the lungs, while the left side receives oxygenated blood from the lungs and pumps it to the rest of the body. This four-chamber setup, with two atria and two ventricles, is what makes the heart a four-chambered organ.

Other descriptions don’t fit human anatomy: a three-chambered heart exists in some animals, but not humans; a gland-like organ with four lobes describes a different tissue type; a solid, two-chambered pump doesn’t capture the heart’s hollow chambers or its complete structure.