Nyirokvezetékek

Nyirokvezetékek, also known as lymphatic vessels, are a crucial part of the lymphatic system. They form an extensive network throughout the body, working in parallel with the circulatory system. Their primary function is to collect and transport lymph, a clear to yellowish fluid, from the tissues back to the bloodstream. This fluid, lymph, is derived from interstitial fluid that leaks out of capillaries into the surrounding tissues.

These vessels begin as tiny, blind-ended capillaries within the tissues. As these capillaries merge, they form larger vessels that gradually increase in diameter. The walls of lymphatic vessels are thinner and more permeable than those of blood vessels, allowing for efficient uptake of interstitial fluid, proteins, fats, and other substances that are too large to re-enter blood capillaries.

Lymphatic vessels contain valves, similar to those in veins, which prevent the backflow of lymph and ensure its unidirectional movement towards the chest. The flow of lymph is propelled by the contraction of surrounding skeletal muscles, changes in thoracic pressure during breathing, and the rhythmic contraction of the smooth muscle in the walls of larger lymphatic vessels.

Along their path, lymphatic vessels pass through lymph nodes, which are small, bean-shaped organs that filter the lymph, removing foreign particles, pathogens, and abnormal cells. The filtered lymph then continues its journey through increasingly larger lymphatic vessels, eventually emptying into the subclavian veins in the upper chest, thus returning the fluid to the blood circulation. This process is essential for maintaining fluid balance in the body, transporting fats absorbed from the digestive system, and playing a vital role in the immune system.