Which of the following organs is NOT part of the excretory system?

The heart is not part of the excretory system. The excretory system primarily consists of organs that are involved in the removal of waste products from the body, such as the kidneys, which filter blood to produce urine, and the lungs, which expel carbon dioxide, a metabolic waste. The skin plays a role in excretion as well, helping to remove waste through sweat. In contrast, the heart's main function is to pump blood throughout the body, facilitating the delivery of oxygen and nutrients while also aiding in the transport of waste products for elimination by other organs. Thus, it is not involved in the direct process of excretion.