From The Bureau of Labor Statistics:

Medical Administrative Assistants perform various administrative tasks to keep the offices of physicians, podiatrists, chiropractors, and other health practitioners running smoothly. They update and file patients’ medical records, fill out insurance forms, and arrange for hospital admissions and laboratory services. They also perform tasks less specific to medical settings, such as answering telephones, greeting patients, handling correspondence, scheduling appointments, and handling billing and bookkeeping. Medical administrative assistants work in well-lighted, clean environments. They constantly interact with other people and may have to handle several responsibilities at once. Most full-time medical assistants work a regular 40-hour week. However, they may work part time, evenings, or weekends.