The pulmonary vein sends the oxygen-rich blood back to the heart, according to NLM. The systemic circulation is the portion of the circulatory system is the network of veins, arteries and blood vessels that transports blood from heart, services the body's cells and then re-enters the heart, the Mayo Clinic noted.he systemic circulation is the portion of the circulatory system is the network of veins, arteries and blood vessels that transports blood from heart, services the body's cells and then re-enters the heart, the Mayo Clinic noted.
Fitness trainers and instructors lead, instruct, and motivate individuals or groups in exercise activities, including cardiovascular exercise (exercises for the heart and blood system), strength training, and stretching.They work with people of all ages and skill levels.roup fitness instructors organize and lead group exercise sessions, which can include aerobic exercise, stretching, muscle conditioning, or meditation. Some classes are set to music. In these classes, instructors may select the music and choreograph an exercise sequence.
About 1 out of 10 fitness trainers and instructors were self-employed in 2014. Fitness trainers and instructors work in facilities such as health clubs, fitness or recreation centers, gyms, and yoga and Pilates studios. These may be standalone centers or centers maintained by other types of establishments for their employees or for members of civic and social organizations.