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:

• Bone marrow
• The Bursa of Fabricius
• The Thymus
• The Foetal Liver

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:

• Lymph nodes
• Spleen
• Mucosal Associated Lymphoid Tissue (MALT)
• Tonsils
• Appendix/caecal pouch
• Ileal Peyer's Patch

• Regional lymphoid tissue

Immune defence

This is a broad topic area.

Immune functions are covered broadly under the primary and secondary lymphoid tissues of the lymphoreticular system with further information under the immunology section.

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

Lymphoreticular Flashcards

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.

Creator

Asher Allison