There shall be in the Service a commissioned Regular Corps and, for the purpose of securing a reserve for duty in the Service in time of national emergency, a Reserve Corps. All commissioned officers shall be citizens and shall be appointed without regard to the civil-service laws and compensated without regard to chapter
51 and subchapter
III of chapter
53 of title
5. Commissioned officers of the Reserve Corps shall be appointed by the President and commissioned officers of the Regular Corps shall be appointed by him by and with the advice and consent of the Senate. Commissioned officers of the Reserve Corps shall at all times be subject to call to active duty by the Surgeon General, including active duty for the purpose of training and active duty for the purpose of determining their fitness for appointment in the Regular Corps. Warrant officers may be appointed to the Service for the purpose of providing support to the health and delivery systems maintained by the Service and any warrant officer appointed to the Service shall be considered for purposes of this chapter and title 37 to be a commissioned officer within the commissioned corps of the Service.