THE INTEGUMENT, OR SKIN 



73 



SKIN 



Epidermis 



Rete 

 Mucosum 



Dennis 



Glands 



Nails 



PERSPIRA- 

 TION .... 



Hairs 



Composition 



Quantity 



Uses 



Ducts 



TOPICAL OUTLINE 



Composed of flattened scales. 

 Horny and transparent. 

 Impermeable to rtuids. 

 No nerves or blood-vessels. 

 Simply protective. 



Surface continually removed by friction. 

 Softer aiid less transparent. 

 Contains pigment cells, 

 (firt's colour to the skin. 

 Fibres of connective and elastic tissues. 

 Numerous blood-vessels and nerves. 

 Drawn up into papillae. 

 I Fat-cells in deeper portion. 



Situated deep in the dermis. 

 Consist of coiled tubes. 

 Surrounded by capillary net- 

 works. 



Nearly straight 



Sweat . . -j through dermis. 



Twisted in epi- 

 dermis. 



Open at the sur- 

 face (pores). 

 Secrete the perspiration. 

 Connected with hairs. 

 _ , Secrete an oily fluid. 



I Sebacec , Discharged into the 



I follicles. 

 I Lubricates the hair 

 I and skin. 

 Thick, horny plates of epidermis. 



f Only where adherent to skin. 

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



root. 

 Pushed forward by growth behind. 



f Interior medullary portion or 

 Shaft . . J pith. 



| Outer cortical or fibrous portion. 

 i Bulb-like at lower extremity. 

 Root . . . -j Imbe( jded 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. 

 f Average about two pounds a day. 

 \ Greater in summer than in winter. 

 [ Greater during activity, 

 f Removal of waste matter, 

 j Tends to reduce the temperature of the body 

 I by its evaporation. 



Secretion 



