Compléter The lymphatic vessels part 3Version en ligne This activity will help you retain information about the lymphatic vessels. par Leah Lloyd 1 movements blood valves backflow muscle gradients edema cardiovascular thin muscle Like veins , the lymphatic tributaries have walls and have to prevent of blood . There is no pump in the lymphatic system like the heart in the system . The pressure to move lymph through the vessels have to come from external sources . These pressure gradients come from skeletal contraction , from respiratory , and from contraction of the smooth within the wall of the vessel . Because there is no rhythmic heart to pump it along , lymph transport is sporadic and much slower than the transport of in the veins . Anything that interferes with the flow of lymph , may cause tissue fluid to accumulate , resulting in .