Il6 APPLIED PHYSIOLOGY 



The message to the mind is called a feeling or sensation. 

 The cells send such true news of everything which they 

 touch that the mind depends upon it wholly for news of 

 the outer world, and is seldom deceived. When something 

 touches the cells so as to hurt them, the mind feels the 

 message as a pain. Then the mind tells the muscle cells 

 to pull the cells away from the thing which hurts them. 

 Pain is a good thing, for it not only tells us when we are 

 being harmed, but it also makes us get away from danger. 



The cells of the body also send word when they are 

 hungry or thirsty. This is different from the hunger and 

 thirst which we feel in the mouth, and which is only the 

 message of the stomach that it is empty. Each cell of 

 the body calls for food, and the mind supplies it by causing 

 the arteries to become larger so as to supply them with 

 more blood. Each cell also sends word to the mind when 

 it is tired and needs rest. 



A nerve which carries messages to the brain is called a 

 sensory nerve, because we feel many of the messages. We 

 do not feel the message as it passes over the nerve, but 

 only when it reaches the mind in the brain. 



220. False messages. Sometimes false messages are 

 sent. If a nerve is pinched or hurt in its course, the mind 

 feels the message as if it came from the end of the nerve. 

 When we pinch the nerve which makes the funny bone in 

 the elbow, it seems to the mind that the little finger is hurt. 

 When the nerves at the knee are squeezed, as when you 

 sit with your legs crossed for some time, they cannot carry 

 the messages from the foot, and so we say that the foot is 

 asleep. 



When the surgeon cuts your flesh, you feel great pain. 

 So he puts a little cocaine upon the nerve through a hollow 

 needle. The cocaine keeps the nerves from sending the 



