This is clipart converted and broken apart that has been released into the public domain because the document says so, and its from NASA, a USA government agency. The publication is called "The Brain in Space:" http://www.nasa.gov/audience/foreducators/topnav/materials/listbytype/The.Brain.in.Space.html espaço ciência cérebro 58294main_The.Brain.in.Space-page-38-diagram-of-involuntary-reflex-action
A glossy sphere with reflen on black background. Esfera brillante con reflejo sobre fondo negro. esfera brilhante reflexo Esfera brilhante w/reflexo. Campo claro com reflexo.