THE INTEGUMENT, OR SKIN 



71 



SKIN 



Epidermis 



Rete 

 Mucosum 



Dennis 



Glands 



Nails 



Sweat 



Ducts 



PERSPIRA- 

 TION . 



TOPICAL OUTLINE 



Composed of flattened scales. 



Horny and transparent. 



Impermeable to fluids. 



No nerves or blood-vessels. 



Simply protective. 



Surface continually removed by friction. 



Softer and less transparent. 



Contains pigment cells. 



Gives colour to the skin. 



Fibres of connective and elastic tissues. 



Numerous blood-vessels and nerves. 



Drawn up into papillse. 



Fat-cells in deeper portion. 



Situated deep in the dermis. 

 Consist of coiled tubes. 

 Surrounded by capillary net- 

 works. 



\ Nearly straight 



through dermis. 

 Twisted in epi- 

 dermis. 



Open at the sur- 

 [ face (pores). 

 Secrete the perspiration. 

 Connected with hairs. 

 Secrete an oily fluid. 



f Discharged into the 



follicles. 

 Secretion j Lubricates the hair 



I and skin. 

 Thick, horny plates of epidermis. 



f Only where adherent to skin. 

 Growth . . < Above, below, and behind at the 



I root. 

 L Pushed forward by growth behind. 



Interior medullary portion or 



pith. 



Outer cortical or fibrous portion. 

 j Bulb-like at lower extremity. 

 1 Imbedded in follicle. 

 Pushed outward by growth at the base. 

 Glands sebaceous (see above). 

 Muscles tend to erect the hair by their con- 

 traction. 

 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. 

 j Removal of waste matter. 



Uses j Tends to reduce the temperature of the body 



[ by its evaporation. 



I Sebaceous 



Hairs 



f Composition 



Quantity 



Shaft 



Root . 



