Lymphatic vessels, known as lymphatics, are crucial in transporting lymph from peripheral tissues to our venous system. This process begins with lymph entering through tiny capillaries that branch through tissues. These capillaries have unique features such as larger diameters, thinner walls, and a distinctive one-way valve system formed by overlapping endothelial cells.
This one-way system allows fluids, solutes, and even pathogens to enter but prevents their return to the intercellular spaces. Notably, lymphatic capillaries are found in almost all organs, with important ones in the small intestine, known as lacteals, which transport absorbed lipids.
From the capillaries, lymph drains into two types of larger vessels: superficial and deep lymphatics. Superficial lymphatics are found deep in the skin and areolar tissues of various membranes, while deep lymphatics accompany deep arteries and veins, serving muscles and other organs.
These vessels converge to form lymphatic trunks that drain into two large collecting vessels: the thoracic and right lymphatic ducts. The thoracic duct collects lymph from the lower half of the body and the left side of the upper body. The smaller right lymphatic duct collects lymph from the right side of the upper body.
Both these ducts serve to reintroduce lymph back into the venous circulation, thereby completing the essential cycle of lymph transport in our bodies. Understanding the lymphatic system is integral to comprehending the body's defense mechanisms and fluid regulation.
Lymphatic vessels, or lymphatics, transport lymph from peripheral tissues to the venous system.
The journey of lymph begins in the thin-walled lymphatic capillaries, which are closed at one end and interspersed with blood capillaries within the loose connective tissue.
Lymph from the lymphatic capillaries drains into superficial and deep lymphatic vessels, merging to form larger trunks that empty into the right lymphatic and thoracic ducts.
The right lymphatic duct, formed by the convergence of the right jugular, subclavian, and bronchomediastinal trunks, drains lymph from the right side of the body above the diaphragm.
Conversely, the thoracic duct drains from all the organs below the diaphragm and on the left side above the diaphragm.
The thoracic duct starts anterior to the vertebral column as cisterna chyli, fed by the right and left lumbar and intestinal trunks.
The thoracic duct ascends posteriorly, fed by the left bronchomediastinal, subclavian, and jugular trunks.
Ultimately, the thoracic and right lymphatic ducts empty into the junction of the internal jugular and subclavian veins on each side of the body, joining the venous circulation.
繁體中文
