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ELEMENTARY PHYSIOLOGY 



r Epidermis 



Bete 



Mucosum 



Dermis 



SKIN 



Glands 



Nails 



PERSPIRA- 

 TION 



^ Hairs 



/ Composition 



4 Quantity 



SUMMARY. 



/ Composed of flattened scales. 

 I Horny and transparent. 

 \ Impermeable to fluids. 

 ] No blood-vessels, and but few nerves. 

 I Simply protective. 



^ Surface continually removed by friction. 

 ( Softer and less transparent. 

 \ Contains pigment cells. 

 * Gives colour to the skin. 

 Fibres of connective and elastic tissties. 

 Numerous blood-vessels and nerves. 

 Drawn up into papilla. 

 Fat-cells in deeper portion. 



Situated deep in the dermis. 

 Consist of coiled tubes. 

 Surrounded by capillary net- 

 works. 



Sweat 



Ducts 



. Nearly straight 

 through dermis. 

 I Twisted in 

 | dermis. 



epi- 



Open at the sur- 

 ^ face (pores). 

 Secrete the perspiration. 

 Connected with hairs. 

 c^Xn/, ' Secrete an oily fluid. 



Discharged 



*> Secretion - 



into 



the follicles. 

 Lubricates the hair 



and skin. 

 Thick, horny plates of epidermis. 



i Only where adherent to skin. 

 Growth . j Above, below, and behind at 



I the root. 

 Pushed forward by growth behind. 



(Interior medullary portion or 

 pith. 

 Outer cortical or fibrous por- 

 tion. 



( Bulb-like at lower extremity. 

 \ Imbedded in follicle. 

 Pushed outward by growth at the base. 

 Glands sebaceous (see above). 

 Muscles tend to erect the hair by their 



contraction. 

 Water. 



Salts especially common salt 

 Little carbonic acid gas in solution. 

 Average about two pounds a day. 

 Greater in summer than in winter. 

 Greater during activity. 

 Removal of waste matter. 



Shaft 



Root. 



i Removal of waste matter. 



v Uses . . | Tends to reduce the temperature of the 

 I body by its evaporation. 



