The lymphatic system acts as a drainage network, removing excess fluid from tissues and returning it to the bloodstream. It operates alongside the circulatory and immune systems, collecting about 15% of fluid that capillaries do not reabsorb. Lymphatic vessels are open-ended networks starting with capillaries that allow large particles like bacteria and immune cells to enter due to their larger gaps compared to blood capillaries. The recovered fluid is called lymph, which flows through progressively larger vessels into subclavian veins after passing through filtering lymph nodes filled with macrophages and T-cells for pathogen defense.