The Service shall consist of (1) the Office of the Surgeon General, (2) the National Institutes of Health, (3) the Bureau of Medical Services, and  (4) the Bureau of State Services, and  the Agency for Healthcare Research and Quality. The Secretary is authorized and directed to assign to the Office of the Surgeon General, to the National Institutes of Health, to the Bureau of Medical Services, and to the Bureau of State Services, respectively, the several functions of the Service, and to establish within them such divisions, sections, and other units as he may find necessary; and from time to time abolish, transfer, and consolidate divisions, sections, and other units and assign their functions and personnel in such manner as he may find necessary for efficient operation of the Service. No division shall be established, abolished, or transferred, and no divisions shall be consolidated, except with the approval of the Secretary. The National Institutes of Health shall be administered as a part of the field service. The Secretary may delegate to any officer or employee of the Service such of his powers and duties under this chapter, except the making of regulations, as he may deem necessary or expedient.123