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.
Gyms and other types of health clubs offer many different activities for clients. However, trainers and instructors often specialize in only a few areas. The following are some types of fitness trainers and instructors: Personal fitness trainers work with a single client or a small group. They may train in a gym or in the clientsâ homes. Personal fitness trainers assess the clientsâ level of physical fitness and help them set and reach their fitness goals.