Watching this resources will notify you when proposed changes or new versions are created so you can keep track of improvements that have been made.
Favoriting this resource allows you to save it in the “My Resources” tab of your account. There, you can easily access this resource later when you’re ready to customize it or assign it to your students.
Lymph vessels are the site of fluid drainage and pump lymph fluid using smooth muscle and skeletal muscle action. The larger ones contain valves to prevent backflow, and they pump towards the heart to return lymph fluid to the the bloodstream by the subclavian veins.
A lymph node is an organized collection of lymphoid tissue, through which the lymph passes on its way to returning to the blood. Lymph nodes are located at intervals along the lymphatic system.
Lymphoid tissue contains lymphocytes, and other specialized structural and functional cells and tissues that have immune system functions.
The lymphatic system is a collection of structures and vessels that drains lymph from blood and has several other functions. In a sense, it is a circulatory system for lymph fluid and the site of many key immune system functions. The structure of the lymphatic system facilitates these general roles.
The lymphatic vessels are the lymphatic system equivalent to the blood vessels of the circulatory system and drains fluid from the circulatory system. The network of lymph vessels consists of the initial collectors of lymph fluid, which are small, valveless vessels, and goes on to form the precollector vessels which have rudimentary valves that are not fully functional. These structures go on to form increasingly larger lymphatic vessels which form co-laterals and have lymph-angions (lymph hearts). The larger lymph vessels contain valves which prevent the backflow of lymph.
The lymphatic system is an active pumping system with active pumping segments with a function similar to that of peristalsis. They lack a central pump (like the heart in the cardio vascular system) so smooth muscle tissue contracts to move lymph along through the vessels. Skeletal muscle contractions also move lymph through the vessels. The lymphatic vessels make their way to the lymph nodes and from the lymph nodes the vessels form into trunks. In general, the lymph vessels bring lymph fluid towards the heart (and above it) to the subclavian veins, which enable lymph fluid to re-enter the circulatory system through the vena cava.
Lymphatic organs are the site of many important functions for the immune system. Lymphoid tissue is found in many organs, particularly the lymph nodes, as well as in the lymphoid follicles in the pharynx, such as the tonsils. Lymph nodes are found Lymphoid tissues contain lymphocytes (a type of highly differentiated white blood cell), but they also contain other types of cells for structural and functional support, such as the dendritic cells, which play a key role in the immune system. The system also includes all the structures dedicated to the circulation and production of lymphocytes, which includes the spleen, thymus, and bone marrow.