The present invention discloses an insertion unit, a bending section and an intubation system for use in a body lumen of a patient. The insertion unit comprises an inner elongated shaft structure being capable of torque transmission around its length axis and having spring-like and flexibility properties and an outer elongated shaft structure at least partially surrounding the inner elongated shaft structure and having spring-like properties and a continuous and flat outer surface. The inner elongated shaft structure has a distal end, and is capable of being connected to an optical head. The insertion unit is configured to transmit pushing and rotation forces along a length of the insertion unit. The integral insertion unit is configured and operable to bend the distal tip in all directions and to fully rotate the distal tip.