Nothing in this chapter prohibits or affects:
(1) A person licensed under this title performing services within his or her scope of practice;
(2) A person performing functions in the discharge of official duties on behalf of the United States government including, but not limited to, the armed forces, coast guard, public health service, veterans' bureau, or bureau of Indian affairs;
(3) A person trained by a federally approved end-stage renal disease facility who performs end-stage renal dialysis in the home setting;
(4) A person registered or certified under this chapter from performing blood-drawing procedures in the residences of research study participants when the procedures have been authorized by the institutional review board of a comprehensive cancer center or nonprofit degree-granting institution of higher education and are conducted under the general supervision of a physician; or
(5) A person participating in an externship as part of an approved medical assistant training program under the direct supervision of an on-site health care provider.