276 ANATOMY AND PHYSIOLOGY 



and a consequent radiation of heat. The use of alcohol before 

 exposure to a low temperature should be avoided, unless some very 

 reliable measure is taken for preventing surface radiation. 



Muscle exercise is accompanied by dilation of surface vessels 

 and escape of heat; this continues for some time after the exercise 

 has ceased, therefore, care should be taken to guard against too 

 great loss of heat and a consequent "cold" due to chilling of the 

 surface, especially when exposed to a draft of air. 



The fact that the body loses heat rapidly by conduction, should 

 warn the nurse against putting cold garments on a delicate patient, 

 and especially against placing a patient in a cold bed. Remember 

 that the body of the patient must furnish the heat to warm the bed 

 and this makes an unnecessary demand upon vitality already 

 impaired by illness. 



Small animals need more heat relatively than large ones 

 because their surface is greater in proportion to their bulk, conse- 

 quently they radiate more heat. During the first three days of 

 the infant's life its metabolism falls; it then begins to rise and 

 reaches the normal average for its size after about two weeks. 



Practical point.- Wrap the new-born child and the young infant 

 more warmly than it seems to need. Remember that it is not 

 yet able to manufacture sufficient heat to keep it comfortable. 



Influence of work upon metabolism it accelerates the proc- 

 esses, with increased consumption of oxygen and elimination of 

 carbon dioxide. 



Influence of light similar in effect (although slight in degree) 

 because light stimulates muscle and tissue tone. 



Influence of darkness It retards metabolism from absence of 

 surface stimuli. 



