how lymph is returned to the heart
Lymph is returned to the heart through a network of lymphatic vessels that help to move the fluid from the tissues back towards the cardiovascular system. These vessels are similar to blood vessels, but they have one-way valves that prevent the backflow of lymph.
As the skeletal muscles contract and relax, they help to squeeze the lymphatic vessels and propel the lymph towards the heart. Additionally, the rhythmic contractions of smooth muscle in the walls of the larger lymphatic vessels, known as lymphangions, help to push the fluid along.
Once the lymph reaches the thoracic duct or the right lymphatic duct in the chest, it is emptied into the bloodstream near the heart. From there, the lymphatic fluid can circulate through the cardiovascular system and be recirculated back into the tissues to maintain fluid balance in the body.