54 PRACTICE OF EQUINE MEDICINE. 



cessation of the bodily functions and of reconstructive change. The 

 blood must be pure arterial blood, and must circulate to sustain 

 life. If it stops circulating death is the result. 



What are the vital organs ? 



The heart and blood-vessels, the lungs and the nervous system. 

 Each of these must continue its work, or life will stop. Their 

 functions are called " the vital functions " — circulation, respiration, 

 and innervation. 



4. MODES OF DEATH. 



Through what channels may death occur? 



Beginning at the heart, the lungs, or the brain. 



Death beginning at the heart takes place how? 



It may take place in one of two ways : suddenly or by syncope, 

 or by a gradual cessation. Death by syncope may occur in one of 

 two ways : by asthenia and loss of irritability — that is, without the 

 strength to contract; or by tonic spasm, where the organ remains 

 contracted till death. By gradual cessation of function, it takes 

 place by anaemia; this is seen after a hemorrhage, where there is 

 insufficient quantity and quality of the blood. 



How does death occur by anaemia? 



The heart must have blood and the power to keep life in ex- 

 istence ; in anaemia there is not enough blood, and it is of too poor 

 a quality to nourish the tissues. The heart may have thepower to 

 contract, but it is empty. 



How does asthenia cause death? 



This comes from a, " without," and sthenos, " strength." It 

 may take place suddenly when caused by lightning, blows in the 

 abdomen (causing death by paralysis of ganglia). The heart is di- 

 lated and filled with blood, but unable to contract. It takes place 

 slowly, as seen in long lingering diseases, where there is loss of 

 nerve force, as in pleurisy; or, again, in animals that are starved; 

 or, if any part of the alimentary tract is occluded by tumors, con- 

 strictions and the like. 



Death beginning at the lungs occurs how? 



The blood remains partly venous by some obstacle of the en- 

 trance of air to the lungs, and occurs when the respiratory muscles 

 fail to act. 



