1 68 APPLIED PHYSIOLOGY 



so that it can pump enough blood to supply the body in 

 spite of the constant leakage backward. The heart may 

 thus become twice its natural size, but there is a limit to 

 its enlargement, and finally it grows weak. If exertion 

 is avoided, such a heart may work perfectly for years. 



The nervous system contained in the heart's muscle makes it the 

 most resistant of all the organs of the body, and the one whose disease 

 is least to be feared. It is the first organ formed in the child, and is 

 the last to die. When it begins to fail, the blood accumulates in the 

 lowest parts of the body, and produces swelling of the feet, which is 

 one of the first signs of heart disease. 



294. Fainting. When the heart is suddenly checked 

 and made weak in its action to such an extent that little 

 blood is driven to the brain, unconsciousness and complete 

 loss of muscular power result, so that the person falls to 

 the ground. The face appears pale, because there is but 

 little blood in it. This paleness and loss of consciousness 

 is called fainting. When a person faints he should be laid 

 upon his back with his head as low as his body, so that the 

 blood may flow to the brain more easily. Cold water should 

 be thrown upon the face so that the sudden shock may 

 stimulate the spinal nerves which hasten the heart's action. 

 In a few seconds the heart beats become stronger, and con- 

 sciousness is regained. Remember not to raise the head 

 of a fainting person. 



295. Effects of alcohol upon the heart. The first effect 

 of alcohol is to increase the force and frequency of the 

 heart beats. This sends more blood through all the body, 

 and there is a feeling of greater strength, which is called 

 stimulation. Men take strong drink for this effect. This 

 feeling comes on within a few minutes after drinking 

 and passes off in the course of an hour, Then the 



