CHAPTER 30 



The physiologic importance of lymph 1 



H. S. MAYERS OX 



Department of Physiology, Tulane University 

 School of Medicine, New Orleans, Louisiana 



CHAPTER CONTENTS 



Methods of Study 



Development and Structure of Lymphatic Vessels 



Lymph vs. Tissue Fluid 



Distribution of Lymphatic Vessels 



General Anatomic Arrangement of Main Trunks 

 Contractility of Lymphatics 

 Exchange of Substances Between Plasma and Lymph 



Extravascular Pool and Circulation of Protein 

 Lymphatic Return and Blood Volume Regulation 

 Transport Function 



Lipids 



Enzymes 



Coagulation Principles 



Iron 



Miscellaneous 

 Significance of Some Regional Lymphatics 



Thoracic Duct 



Hepatic Lymph 



Pulmonary Lymphatics and Edema 



Cardiac 



Renal 

 Lymph and Lymphatics in Shock 



Anaphylactic Shock 



Traumatic Shock 



Burns 



Permeability Factors 

 Permeability of Lymphatic Vessels 



from a physiologic point of view, the lymphatic 

 system is primarily a drainage system. Its need arose 

 phylogenetically with the development of a high 

 pressure circulation. The latter development, de- 

 signed to insure an adequate supply of oxygen to 



1 The work described as emanating from this laboratory was 

 supported by grants from the Research and Development 

 Command, U. S. Army, the American Heart Association, and 

 the U. S. Public Health Service. 



tissues, created a situation favoring transudation of 

 fluid and other substances from the capillaries. An 

 increase in plasma protein served to counteract 

 partially this leakage, since the plasma proteins 

 exerted an osmotic pressure. There still remained, 

 however, the problem of clearing the tissue spaces of 

 substances which had leaked out of blood capillaries 

 or which were not absorbed into the blood stream. 

 In this sense, the lymphatic system must be regarded 

 as a homeostatic mechanism, important in the 

 maintenance of the constancy of the milieu interieur. 

 It is this point of view that will be emphasized in the 

 present discussion. The role of the lymphatic system 

 in the transport of materials from the liver and in- 

 testines to the blood stream will also be considered. 

 No attempt will be made to cover all that has been 

 done regarding lymph and lymphatics nor will the 

 extensive literature on lymph nodes and lymphoid 

 tissues be discussed. Various aspects of the general 

 subject have been treated in depth during the last 

 several decades in reviews and monographs (45, 58- 

 60, 62, 66, 88, 135-137, 185, 189, 215, 223, 227, 234) 

 and the reader is referred to these sources for basic 

 material not included in the present review. Two 

 recent monographs will be found most helpful (189, 

 234). The latter source will interest those concerned 

 with clinical implications of disturbed lymphatic 

 function. It also includes results of work in Hungarian 

 and Russian laboratories not readily available in the 

 English literature. 



METHODS OF STUDY 



Although lymphatics presumably had been seen 

 by members of the Alexandrian school (Herophilos, 



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