Answer by Nishant Trivedi:
The lymphatic system is a critical network of vessels and nodes that plays a role in fluid balance and immunity. Lymphatic vessels that exit from lymph nodes have a high concentration of immune cells (white blood cells). Lymphatic networks around the digestive tract are rich in fats and proteins (chyle). The lympathic system is circulated as a side effect of moving our muscles, unlike our blood circulation which is pumped along by the heart. Unfortunately, cancer cells can spread to other parts of the body through lymphatic drainage from tissues — this is why in breast cancer, for example, surgeons perform a “sentinel lymph node biopsy” to check for malignant cells. If there are no malignant cells in the primary lymph near a possible cancer, there is a likelihood that the cancer has not spread to other parts of the body. This is a grossly simplified picture – so please pardon the lack of detail.
Also, there is one infectious disease process that comes to mind regarding the lymphatic system, and that is lymphatic filariasis. Certain parasites spread by mosquitos cause profound edema (or swelling) of the affected extremities by blocking lympathic vessels and preventing fluid drainage.
Hope this helps! If you take away anything — just remember that the lymphatic system has roles in mediating our immune system, our fluid balance, and is circulated through active skeletal muscle movement.