IQO EQUINE PHYSIOLOGY. 



ANIMAL HEAT. 



The process of nutrition and oxidation of food products is ac- 

 companied by the evolution of heat. This gives the body an 

 average temperature which, in the horse, varies between 37.5° 

 C. and 38° C. 

 Sources of Animal Heat. 



This is the result of oxidation of the h)^Qrocarbons and carbo- 

 hydrates as well as the combination of hydrogen and oxygen form- 

 ing water. 



Heat Ufiiis. — The English heat unit is the amount of heat re- 

 quisite to raise one pound of water, 1° F. In the horse for each 

 kilo of weight, 2.1 heat units are set free per hour, or for an ani- 

 mal of 500 kilos, as an example, 1050 heat units per hour, or in a 

 day 2.1x500x24=25200 heat units. In a man of 140 pounds, 

 13,440 heat units are thrown off in the same time. 



The temperature is raised by exercise, due to increased tissue 

 metabolism, and the urea is increased. 



The temperature of the blood of the portal vein is usually sev- 

 eral degrees higher than the average temperature of the body. 



SECRETION. 



Secretion (Flint) is the act by which fluids holding certain 

 principles in solution are separated from the blood, or are manu- 

 factured by special organs from mateiials furnished by the blood. 

 These have a function to perform. 



An Excretion contains elements not formed in the substance of 

 the gland which have no function to perform and are extracted 

 from the blood. 



There are always two periods in every secreting organ — 



I st, The pejiod of i-epose, or period of no secretion ; though the 

 manufacture of the solid elements is constantly going on. 



2nd, The period oifimctiojial activity, in which the formed ele- 

 ments are washed out by the water from the blood, which is eight 

 times as abundant in this stage. 



Classes of secreting organs. 



1. The most simple is a basement membrane covered with flat- 

 tened cells, as the peritoneum, 



2. The next is more secreting surface with not much more space, 

 as the simple depressions of Lieberklihn in the small intestines. 



