👉 Thymines are a group of tiny, muscular tubes that connect the lungs to the rest of the body. These tubes have one end on each side of the heart and two ends on each side of the diaphragm (the stomach). The walls of these tubes are lined with smooth muscle cells called myofibrils. They are responsible for breathing by moving air molecules through the lungs. Thymines also play an important role in the respiratory process, where they help to pump oxygen