270 ANATOMY AND PHYSIOLOGY 



That of the pituitary body (or hypophysis) restrains growth of 

 osseous tissue and influences metabolism, establishing a tolerance 

 for sugars. 



That of the ovary is associated with the function of the mam- 

 mary gland and the uterus, and influences the action of vaso- 

 motor nerves of the systemic circulation. This internal secretion 

 is furnished by the corpus luteum (p. 349). 



In addition to the above may be mentioned: 



The spleen and lymph glands which supply white cells to blood. 



The marrow of bones which supply red cells to blood. 



The testes which produce spermatozoa. 



The secretions of the organs named, serve various purposes, 

 aiding or influencing nutrition, or assisting in the formation of 

 other substances. 



EXCRETION 



Excretions. These are the substances which must be elimi- 

 nated from the body. 



All tissue action uses up some material, leaving a varying rem- 

 nant of waste matter which cannot be utilized like the ashes from 

 a fire. These wastes appear either dissolved in water as urine and 

 perspiration, or in the form of gas or vapor. 



Tissue waste may be reduced ultimately to comparatively few 

 substances, the most important being urea, carbon dioxide, various 

 salts and water. Urea is most abundant in urine, COz in exhaled 

 air, and all of these in small quantity in perspiration. 



Therefore, the organs of elimination are: 



The kidneys, which excrete urine. 



The skin, which excretes perspiration. 



The lungs, which exhale carbon dioxide, organic matters, am- 

 monia and water. 



To these may be added the liver and the intestinal canal. 



The liver excretes waste matters with the bile and forms urea. 



The intestinal canal excretes small quantities of tissue waste 

 (gases, water, mucus, etc.). 



GENERAL METABOLISM 



We have studied the framework of the body with its various 

 connections and adaptations, its coverings and its cavities, the 



