lymphangion

A lymphangion is the basic functional unit of the lymphatic system. It is a segment of a lymphatic vessel located between two semilunar valves. These valves, similar to those found in veins, are crucial for the unidirectional flow of lymph. The lymphangion contracts rhythmically, propelling lymph through the lymphatic network towards the thoracic duct and right lymphatic duct, where it eventually returns to the bloodstream.

The structure of a lymphangion allows it to act as a pump. The smooth muscle in the wall of the lymphatic vessel contracts spontaneously, squeezing the lymph forward. When the lymphangion contracts, the valves at either end close, preventing backflow. As the lymphangion relaxes, the valves open, allowing it to fill with lymph from the preceding segment. This coordinated contraction and relaxation of successive lymphangions create a slow but steady flow of lymph.

The health and proper functioning of lymphangions are vital for maintaining fluid balance in the tissues, transporting fats absorbed from the digestive system, and playing a significant role in the immune system by carrying immune cells and filtering pathogens. Disruptions in lymphangion function can lead to lymphedema, a condition characterized by swelling due to the accumulation of lymph fluid.