ABSTRACT

This chapter explores the anatomy and physiology of the spleen in both humans and animals, looking at reactions to physical activity and other stressors. It considers mechanisms underlying changes in dimensions of the spleen and their practical significance in terms of changes in oxygen transport, blood clotting and the immune response. The chapter makes a critical examination of the contribution of the spleen to the human exercise response. It examines likely mechanisms causing any changes in splenic dimensions. The biological importance of the spleen seems to vary substantially from one species to another. The English cardiovascular physiologist Sir Joseph Barcroft and his colleagues first drew attention to the contribution of the spleen to running ability in the dog and cat. The spleen is also is an important component of the body's immune system, contributing leukocytes and platelets to the general circulation as part of the "fight or flight" reaction.