Lymphatic System Overview - Anatomy & Physiology
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Introduction
The lymphatic system can be divided into two anatomical and functional subsets: lymphatic vessels that carry lymph around the body, and the lymphoreticular system which describes the lymphoid tissues. The lymphatic system has three functions - immune defence, removal of interstitial fluid from tissues and the transport of fats.
Primary (or central) lymphoid tissues can also be referred to as primary lymphoid organs. Maturation of lymphocytes and lymphopoiesis occurs in the primary lymphoid tissues, with different tissues responsible for maturing different types of lymphocyte.The primary lymphoid tissues are:
Secondary (or peripheral) lymphoid tissues or secondary lymphoid organs provide a site for immune responses to occur and are populated by relatively mature T cells and B cells, macrophages and dendritic cells with each tissue providing a different environment.The secondary lymphoid tissues are:
- The Lymph nodes
- The Spleen
- Mucosal Associated Lymphoid Tissue or MALT
- The Tonsils
- The Appendix/caecal pouch
- The Ileal Peyer's Patch
- Regional lymphoid tissue
Immune defence
The main functions of the lymphoreticular system are removal of senescent cells and production of immune cells. Immune functions are covered broadly under the primary and secondary lymphoid tissues of the lymphoreticular system
Removal of interstitial fluid
Details can be found here.
Transport of lipids
Chylomicrons transport digested lipids, however these are too large to enter the blood stream directly and thus enter the lymphatic system before being released into the blood stream. Further details can be found here.
Test yourself on the lymphoreticular flash cards
References
Texts:
- Dyce, K.M., Sack, W.O. and Wensing, C.J.G. (2002) Textbook of Veterinary Anatomy. 3rd ed. Philadelphia: Saunders.
- Janeway, C.A., Travers, P., Walport, M. and Shlomchik, M.J. (2005) Immunobiology: The immune system in health and disease. 6th ed. New York: Garland Science Publishing.
- McGeady, T.A., Quinn, P.J., FitzPatrick, E.S. and Ryan, M.T. (2006) Veterinary Embryology. Oxford: Blackwell Publishing.
- Ross, M.H. and Pawlina, W. (2006) Histology: A text and atlas. 5th ed. Baltimore: Lippincott Williams & Wilkins.
- Sjaastad, O.V., Hove, K. and Sand, O. (2004) Physiology of Domestic Animals. Oslo: Scandinavian Veterinary Press.
- Tizard, I.R. (2004) Veterinary Immunology: An Introduction. 7th ed. Philadelphia: Saunders.
Literature:
- Dasso, J.F., Obiakor, H., Bach, H., Anderson, and Mage, R.G. (2000) A morphological and immunohistological study of the human and rabbit appendix for comparison with the avian bursa. Developmental & Comparative Immunology 24(8): pp.797-814.
- Metcalfe, D.D., Baram, D. and Mekori, Y. (1997) Mast Cells. Physiological Reviews 77(4): pp.1033-1064.
- Nance, D.M. and Sanders, V.M. (2007) Autonomic innervation and regulation of the immune system (1987-2007). Brain, Behavior, and Immunity 21(6): pp.736-745.