6 HUMAN PHYSIOLOGY. 



vessels of the body, and especially those in relation to the villi of the small 

 intestine, constitute the absorptive apparatus, the function of which is the in- 

 troduction of new material into the blood. The heart and blood-vessels 

 constitute the circulatory apparatus, the function of which is the distribution 

 of blood to all portions of the body. The lungs and trachea, together with 

 the diaphragm and the walls of the chest, constitute the respiratory apparatus, 

 the function of which is the introduction of oxygen into the blood and the 

 elimination from it of carbon dioxid and other injurious products. The 

 kidneys, the ureters, and the bladder constitute the urinary apparatus. The 

 skin, with its sweat-glands, constitutes the perspiratory apparatus, the func- 

 tions of both being the excretion of waste products from the body. The liver, 

 the pancreas, the mammary glands, as well as other glands, each form a 

 secretory apparatus which elaborates some specific material necessary to the 

 nutrition of the individual. The functions of these different physiologic 

 apparatus e. g., digestion, absorption of food, elaboration of blood, circu- 

 lation of blood, respiration, production of heat, secretion, and excretion 

 are classified as nutritive functions, and have for their final object the preserva- 

 tion of the individual. 



The nerves and muscles constitute the nervo-muscular apparatus, the 

 function of which is the production of motion. The eye, the ear, the nose, 

 the tongue, and the skin, with their related structures, constitute, respectively, 

 the visual, auditory, olfactory, gustatory, and tactile apparatus, the function 

 of which, as a whole, is the reception of impressions and the transmission 

 of nerve impulses to the brain, where they give rise to visual, auditory, 

 olfactory, gustatory, and tactile sensations. 



The brain, in association with the sense organs, forms an apparatus related 

 to mental processes. The larynx and its accessory organs the lungs, 

 trachea, respiratory muscles, the mouth and resonant cavities of the face 

 form the vocal and articulating apparatus, by means of which voice and 

 articulate speech are produced. The functions exhibited by the apparatus 

 just mentioned viz., motion, sensation, language, mental and moral mani- 

 festations are classified as functions of relation, as they serve to bring the 

 individual into conscious relationship with the external world. 



The ovaries and the testes are the essential reproductive organs, the former 

 producing the germ-cell, the latter the spermatic element; together with their 

 related structures the fallopian tubes, uterus, and vagina in the female, 

 and the urogenital canal in the male they constitute the reproductive 

 apparatus characteristic of the two sexes. Their cooperation results in the 

 union of the germ-cell and spermatic element and the consequent develop- 

 ment of a new being. The function of reproduction serves to perpetuate the 

 species to which the individual belongs. 



