IMMUNOLOGY

Detailed explanation-1: -There is no pump in the lymphatic system like the heart in the cardiovascular system. The pressure gradients to move lymph through the vessels come from the skeletal muscle action, respiratory movement, and contraction of smooth muscle in vessel walls.

Detailed explanation-2: -As lymph capillaries collect interstitial fluid from tissues, the pressure in the lymph capillaries grows. This increasing pressure moves the lymph fluid forward toward the heart. Everywhere in your body, your lymphatic capillaries collect lymph and move it into larger lymphatic vessels.

Detailed explanation-3: -Lymph is transported throughout the lymphatic vasculature by intrinsic phasic contractions generated by the lymphatic muscle of collecting lymphatics that, along with valves, are necessary for unidirectional lymph flow.