Summary
Vessels and nodes that return tissue fluid to the blood and house immune cells.
In depth
Lymph is excess tissue fluid collected by lymph capillaries and returned near the heart. Lymph nodes filter pathogens; lacteals absorb fats. Swelling (oedema) results from lymph blockage.
Lymph flow is driven by muscle movement and one-way valves. The spleen filters blood; the thymus matures T cells. Tonsils guard entry points.
Example: lymph node swelling indicates immune activity.
The system collects about 3 litres of fluid per day that leaks from capillaries, and returns it to the blood via the thoracic duct and right lymphatic duct to subclavian veins. Lymph vessels have valves and rely on muscle movement. Lacteals absorb fats from the gut. Lymph nodes (about 600) contain lymphocytes and macrophages that monitor lymph for pathogens, and swell during infection. The spleen filters blood and recycles old red cells, the thymus matures T cells, and tonsils and Peyer's patches guard mucosal entry.
Lymphoedema is swelling from blocked lymph, as in filariasis or after lymph node removal. Cancers spread via lymph, so nodes are examined in staging. Lymphomas are cancers of lymphocytes.
Example: swollen neck glands during a sore throat are lymph nodes mounting an immune response.
Frequently asked questions
What is Lymphatic System?
Vessels and nodes that return tissue fluid to the blood and house immune cells.
Which area of biology covers Lymphatic System, and how advanced is it?
Lymphatic System is one of the 51 topics in Human Physiology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Blood Vessels, Circulatory System, Heart Structure.
Can you give an example of Lymphatic System?
Lymph nodes swell during infection.
What should I learn before Lymphatic System?
Work through the Beginner topics in Human Physiology first, such as Homeostasis, Tissues and Organs, Skeletal System, then return to Lymphatic System. Intermediate topics assume the Beginner vocabulary.
What topics are related to Lymphatic System?
The closest topics to Lymphatic System are Blood Vessels, Circulatory System, Heart Structure, Fluid Compartments. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Lymphatic System?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Lymphatic System. To practise the whole of Human Physiology, use the Human Physiology quiz.
How is Lymphatic System different from Blood Vessels?
Lymphatic System: Vessels and nodes that return tissue fluid to the blood and house immune cells. Blood Vessels: Arteries carry blood away from the heart, veins return it and capillaries exchange materials. Read both side by side and note what each one explains.
How should I study Lymphatic System step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Blood Vessels and explain the difference aloud. Finally, take the Human Physiology quiz and come back to this page for any question you miss.