A channel system for use with a conventional endoscope is provided. The system comprises a collapsible access channel that is connected to a first distal end of the endoscope. The collapsible channel includes an access opening communicating between the two ends of the collapsible channel. The endoscope may be provided with a protective sheath and/or an endcap that is integral with the collapsible channel. The collapsible access channel allows a physician to insert functional instruments such as a biopsy device or tubes for supplying air, water, suction and irrigation.