A flow control system, for example for blood plasma or other medical fluids, comprises a plurality of flexible, collapsible flow conduits for the selective and aseptic transfer of fluids between various locations through said conduits. Switching means are provided for selectively collapsing a plurality of separate sections of the conduit to block fluid flow therethrough, to selectively define specific and variable fluid flow paths in the flow conduit. In accordance with this invention, the switching means defines a cam plate, which in turn defines a generally flat face positioned adjacent portions of the flow conduit. Pivot means are provided causing the cam plate to be rotatable about an axis normal to the flat face. Also, a cam connecting system is disclosed, to adapt it to pass through an openable door.