Final answer:
The American Medical Association (AMA) is the national professional organization that advocates for physicians and their patients, aiming to improve medical practice and public health.
Step-by-step explanation:
The national professional organization that advocates for physicians and their patients is the American Medical Association (AMA). Founded in 1847, the AMA has played a critical role in the advancement of medicine and the professional development of physicians. This organization actively works on behalf of physicians to improve medical practice, enhance public health, and promote the betterment of the medical profession. Notably, the AMA has historically held significant prestige within the medical community, despite local chapters initially refusing to admit Black physicians, which led to the formation of the National Medical Association as an alternative representative body for Black physicians.