Insulin is not a cure for diabetes, for a deficient pancreas remains a 

 deficient pancreas. Insulin obtained from the pancreas glands of cattle can 

 be used to make up for the body's deficiency. By attending to his diet and 

 adding insulin regularly to the blood-stream, a person suffering from dia- 

 betes may continue to live with a deficient pancreas and carry on his normal 

 activities for many years. People often ask. Why should not the insulin or 

 pancreas tissue be taken in with the food ? The answer is that the digestive 

 fluids, including those of the pancreas itself, destroy insulin. 



Hormones and Emergencies In our day-by-day activities the exertions 

 and energy output of the body are constantly changing. Changes in the 

 secretion of insulin and thyroxin accompany changes in the rate of metab- 

 olism, the rate of breathing, and the pulse rate. Through these variations 

 the organism adjusts itself minute by minute. An emergency, however, 

 places exceptional strains upon the body. A situation may threaten one's 

 safety or arouse one's rage. 



When the organism is under great stress the adrenals come into action, 

 stimulated by a nerve impulse from the autonomic system. The medulla, or 

 core of the adrenal capsule, discharges into the blood the hormone epineph- 

 rine sometimes called also adrenin. Like thyroxin, epinephrin accelerates 

 the general metabolism of the body, but it does not act equally on all parts. 

 We have no sensation in the adrenal, and we cannot "feel" the epinephrin 

 in the blood. But the changes produced by epinephrin are obviously adap- 

 tive. When the hormone is in the blood, it increases the fuel and hastens 

 the blood-fiow to the muscles; it raises the tension of the muscles, widening 

 the nostrils and deepening the breath, setting the eyes and all the senses on 

 the alert. A person who shows some of these characteristics under normal 

 conditions probably has an excess of epinephrin in his blood (see illustra- 

 tion, p. 314). In many cases such a person is likely to make trouble for others, 

 or for himself. 



Adrenin decreases the blood supply to the digestive system, but makes 

 more blood available to the muscles. It seems to reduce fatigue even while 

 energy output increases. When the amount of this hormone is increased by 

 great excitement or sudden fright, the skin turns white, the eyes open wide, 

 the heartbeat is accelerated, and blood pressure rises. The organism is all 

 set for fighting or for running away. If it sustains its effort under high ten- 

 sion, epinephrin continues to come into the blood. The effect is to raise the 

 entire level of energy output to what athletes sometimes call "second wind". 



After the emergency is over, the metabolism in the various organs and 

 tissues returns to the usual rates. From our own experience we know that 

 after any great excitement we are actually weaker than at ordinary times. 

 In fact, we nearly always feel a decided letdown after any excitement. 



The cortex, or rind, of the adrenal produces another hormone, called 



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