STRUCTURE OF THE SKIN 



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dioxide are dissolved. Some of the wastes are eliminated by 

 sweat glands. Each sweat gland ends in an opening in the epi- 

 dermis called a pore. The perspiration leaves the body through 

 the pores. Specialized epithelial cells form roots of hairs in the 

 deeper layers of the true skin. These hairs grow out through 

 hair follicles which are formed by the downward extension of the 

 epidermis. Only the lower part of the hair lives and grows. 

 Associated with the hair follicle is an oil gland. This supplies 

 nourishment to the hair since it opens either into a hair follicle 

 or upon the surface of the skin. The oil keeps the skin flexible 

 and soft. Within the tiny papillae or end-organs in the dermis 

 are specialized nerves for receiving the sensations of pressure, 

 pain, and temperature. Fat cells are also found in the dermis. 



Functions of the skin. The skin is an organ of excretion. By 

 means of the millions of blood vessels, sweat glands, and pores, it 



Hairs grow from hair follicles formed by 

 the downward extension of the epidermis 

 into the true skin. The hair in the bottom of 

 the follicle enlarges to form a bulb which is 

 well supplied with blood vessels. 



A sweat gland is composed of a duct and 

 a coiled portion surrounded by capillaries. 

 Wastes gathered from the blood by the 

 glands are eliminated through a pore in the 

 skin. 



