There are seven uniformed services: The five armed forces plus the Public Health Service Commissioned Corps, which falls under the Department of Health and Human Services, and the National Oceanic and Atmospheric Administration Officer Corps, which falls under the Commerce Department.
Officers in the PHS Corps and NOAA Corps wear Navy uniforms and use Navy ranks. There are no enlisted or warrant personnel in these services.
The U.S. surgeon general, a vice admiral, directs the PHS Corps, which provides licensed medical and health sciences professionals to the PHS, DHHS, other uniformed services and other government agencies.
The NOAA Corps is made up of technically skilled science officers who can be incorporated into the armed forces in wartime. In peacetime, the corps supports defense requirements in addition to its purely nonmilitary scientific projects at sea, in the air and in laboratories.
Source: Department of Defense