242 



glands which secrete oil onto the shaft 

 of the hair; the small blood vessels which 

 supply all the living cells and which 

 branch into numerous capillaries around 

 the coil of the sweat glands; and the 

 special sense organs and nerve endings. 

 These are well protected by the epi- 

 dermis, yet are sufficiently near the sur- 

 face to provide sensations of touch, heat, 

 cold, and pain. 



Ventilation and the skin. For many 

 years it was thought that ventilation of 

 rooms where many people were gathered 

 was important in order to replace the 

 oxygen used and to remove the carbon 

 dioxide breathed out. Now we know 

 that "bad" air affects the skin. You have 

 just read that regulation of body tem- 

 perature is one of the very important 

 functions of the skin. And you know 

 that this regulation is largely dependent 

 on proper evaporation of moisture from 

 the skin. When large numbers of people 

 are gathered in a small space which has 

 not enough ventilation, the air soon be- 

 comes warm and saturated with water 

 vapor. Evaporation slows up; the skin 

 does not have an opportunity to lose 

 heat; and its temperature rises. Experi- 

 ments on human subjects have shown that 

 the feelings of discomfort, headache, 

 drowsiness, and general restlessness under 

 such conditions are due, at least in large 

 part, to the lack of heat regulation. In air 

 conditioning, therefore, both tempera- 

 ture and humidity are controlled. 



The care of the skin. Since the skin is 

 a complex organ and is so important to 

 our well-being, it is important to keep it 

 healthy. Largely because sweat and oil 

 are excreted onto the surface of the skin, 

 much dirt ant! foreign material tend to 



How a Complex An'mial Uses Food unit iv 



collect on it. Soap and warm water are 

 needed to remove this. It is important to 

 keep the pores of the oil glands from 

 clogging with dirt. The clogged pores of 

 oil glands are known as blackheads. 



It is important to know that the skin 

 must be protected against excessive sun- 

 light. Some of the cells in the skin contain 

 pigment (coloring matter). Dark skinned 

 people have large amounts of pigment; 

 fair skinned people have small amounts 

 of pigment. Sunlight in moderate doses 

 increases the amount of pigment in most 

 people and the skin tans, thus protecting 

 it against the burn of the sun's ultraviolet 

 rays. In some people the cells do not pro- 

 duce much pigment and the person bums 

 instead of tanning. This mav be very 

 serious. But the danger of ultraviolet rays 

 exists even for people who tan. 



Under regulation by the Federal Food, 

 Dru^-, and Cosmetic Act cosmetics are 

 required to be free from poisonous sub- 

 stances. It is well to remember, however, 

 that certain cosmetics, just as certain 

 soaps, may be more or less injurious to 

 your particular skin. 



Disorders of the skin. Younger people, 

 particularly those of high school age, 

 sometimes suffer from ac7ie (ack'knee) 

 which is another name for pimples. Pim- 

 ples appear on the face and sometimes on 

 the upper part of the body. The cause 

 may be deep-seated and difficult for a 

 physician to find and remedy. For some 

 unknown reason the oil glands become 

 involved, the secretion remaining in the 

 duct. Then, if bacterial infection sets in, 

 a little red swelling appears. This pimple 

 may disappear in a few days but fre- 

 quently it breaks open and pus is dis- 

 charged. The person who suffers from 



