Persons exempt from chapter.

These persons are exempt from this chapter while engaged in the proper discharge of their professional duties: (1) persons authorized under the laws of this State to practice medicine and surgery; (2) commissioned medical or surgical officers of the United States Army, Navy, or Marine hospital service; (3) registered nurses; (4) students in schools, colleges, and universities who practice barbering only upon students in the school, college, or university premises for the purpose of earning part of their school expenses; (5) undertakers; (6) persons authorized by state law to practice cosmetology only when they are practicing in salons or schools of cosmetology.