An internal medicine physician is a personal physician who provides long-term, comprehensive care in the office and the hospital, managing both common and complex illness of adults, and the elderly. Internists are trained in the diagnosis and treatment of diseases affecting the heart, blood, kidneys, joints and digestive, respiratory and vascular systems. They are also trained in the essentials of primary care medicine, which incorporates an understanding of disease prevention, wellness, substance abuse, mental health, and effective treatment of common problems of the eyes, ears, skin, and nervous system.