450 



ORGAN SYSTEMS OF MAN 



gallons per day), a disease known as dia- 

 betes insipidus. Such an afflicted person 

 must drink tcpmendous quantities of water 

 to offset this great loss. 



No hormones have been purified from 

 the posterior lobe, but some crude extracts 

 have been prepared which, when injected 

 into animals, cause a powerful contraction 

 of the uterus and a constriction of the small 

 arteries, resulting in a general rise in blood 

 pressure. One of these fractions has some 

 therapeutic value in increasing uterine con- 

 tractions during labor. Much less is known 



about the hormones produced by the poste- 

 rior lobe of the pituitary, perhaps because 

 they are not so striking in their effects as are 

 those from the anterior lobe. 



In this chapter we have seen how the 

 many parts of a complex animal are coordi- 

 nated into an integrated whole. We shall 

 examine in the next few chapters the organ 

 systems responsible for the energy that 

 keeps the machine going, using man again 

 as the principal animal for study. 



