FUNCTIONS OF THE SKIN 391 



395. Functions of the Skin. Some of the functions 

 of the skin have already been given. It is, first of all, a 

 covering for the body; it also contains the structures 

 that act upon the nerves of touch (cf. 392). In giving 

 off perspiration it is an organ of excretion, like the kidneys 

 (cf. 380). It is likewise one of the regulators of the 

 body's temperature: the skin and the lungs together 

 (cf. 383) enable the body to cast off the heat it does not 

 need. 



The body remains at the normal temperature (98.6 F.) 

 whether we exercise or remain at rest, when the weather 

 is cold as well as when it is hot. This temperature there- 

 fore represents a condition of balance in the body's heat 

 supply: at 98.6 F. we gain heat and lose heat in equal 

 amounts. When we are warm, the blood rushes to the 

 surface of the body. The skin then radiates heat rapidly; 

 a rapid flow of perspiration also takes place. By these 

 means the blood is cooled, and the body's heat is lowered. 



If the heat of the body needs to be saved, as when we are 

 in a cool room, the blood vessels near the surface grow 

 smaller, and less blood comes to the skin. Thus the body 

 loses less heat. If the lack of blood near the skin con- 

 tinues for a time, we feel cold. Then, if we are wise, we 

 raise the temperature of the room, or wear warmer cloth- 

 ing. When the blood vessels remain tightly closed, as in 

 some forms of fever, we have a feeling of cold (a chill), 

 even when the body has heat that needs to be given off. 



Bathing. The need of bathing has already been given (cf. 223). 

 The skin becomes covered with body wastes from the evaporated 

 perspiration, with oil from the sebaceous glands, with dust from the 

 clothing and the air, and with dead epidermis. The best kind of a 



