The term 'heart line' refers to the two major vessels that carry blood away from the heart: the AORTA and the ARTERY. The AORTA is a five-letter word, and the ARTERY is a six-letter word. The AORTA is the largest ARTERY in the body, carrying oxygenated blood away from the left ventricle of the heart to the rest of the body. The ARTERY is a smaller vessel that carries oxygenated blood away from the right ventricle of the heart to the lungs. Together, these two vessels form the heart line, providing oxygenated blood to the entire body.