Chap. XVIII] 



SUMMARY 



359 



Func- 

 tions 



Skin<^ 



SUMMARY 



1. Protective covering for deeper tissues. 



2. As a sense organ. 



3. As an excretory organ — Elimination of waste matter 



in sweat. 



' Absorption through unbroken 



A A„„« u u- skin is limited. 



4. As an absorbmg organ < . , 



I Absorption rapid if epidermis 

 [ is removed. 



5. Most important as organ in heat regulation. 

 Small amount oxj'gen taken in. 

 Small amount carbon dioxide 



is thrown off. 



' Practically 

 dead cells 

 being con- 

 stantlj^ shed 

 and renewed 

 from germi- 

 native layer. 



6. As a respiratory organ 



Epidermis 

 is a strati- 

 fied epi- 

 theUum 



1. Superfi- 

 cial or 

 horny 



b. 



Soft protoplasmic cells that 

 are constantly multiplying 

 by cell division. 



Stratum 



corneum 

 Stratum 

 lucidum 

 Stratum 

 granulo- 

 sum 

 Germina- 

 tive or 

 Con- I Mal- 



sists of 1 I pighian 



Papillary layer — papillae are minute coni- 

 cal elevations of the cutis vera. They 

 Derma is contain looped blood-vessels and ter- 



a layer minations of nerve-fibres called tactile 



of con- { corpuscles. 



nective f Bundles of fibrous and elastic 



tissue 2. Reticular I tissue, with network of 

 layer blood-vessels, lymphatics, 



and nerves. 



Blood-vessels — They are found in derma only. Send branches 

 to papillae and glands of skin. Capable of holding one-half to 

 two-thirds total amount of blood in body. 

 f 1. Vasomotor. 

 2. Two sets concerned in temperature sense. 

 Nerves { 3. Nerves concerned in sense of touch or pressure. 



4. Nerves stimulated by pain. 



5. ]\[otor nerves from sympathetic system. 

 r Nails. 



Appendages 



Hair. 



Sebaceous glands. 



Ceruminous glands. 



Sweat-glands. 



