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.
Customer-service skills. Many fitness trainers and instructors must sell their services, motivating clients to hire them as personal trainers or to sign up for the classes they lead. Fitness trainers and instructors must therefore be polite, friendly, and encouraging, to maintain relationships with their clients.