64 HUMAN PHYSIOLOGY. 



Destruction of a secreting gland abolishes the secretion peculiar to it, 

 and it cannot be formed by any other gland ; but among the excreting 

 organs there exists a complementary relation, so that if the function of one 

 organ be interfered with, another performs it, to a certain extent. 



CLASSIFICATION OF THE SECRETIONS. 

 PERMANENT FLUIDS. 



Serous fluids. Vitreous humor of the eye. 



Synovial fluid. Fluid of the labyrinth of the internal 



Aqueous humor of the eye. ear. 



Cerebro- spinal fluid. 



TRANSITORY FLUIDS. 



Mucus. Gastric juice. 



Sebaceous matter. Pancreatic juice. 



Cerumen (external meatus). Secretion from Brunner's glands. 



Meibomian fluid. Secretion from Leiberkuhn's glands. 



Milk and colostrum. Secretion from follicles of the large 



Tears. intestine. 



Saliva. Bile (also an excretion). 



EXCRETIONS. 



Perspiration and the secretion of Urine. 



the axillary glands. Bile (also a secretion). 



FLUIDS CONTAINING FORMED ANATOMICAL ELEMENTS. 



Seminal fluid, containing spermatozoids. Fluid of the Graafian follicles. 



The essential apparatus for secretion is a delicate, homogeneous, 

 structureless membrane, on one side of which, in close contact, is a capil- 

 lary plexus of blood vessels, and on the other side a layer of cells whose 

 physiological function varies in different situations. 



Secreting organs may be divided into membranes and glands. 



Serous membranes usually exist as closed sacs, the inner surface of which 

 is covered by pale, nucleated epithelium, containing a small amount of 

 secretion. 



The serous membranes are the pleura, peritoneum, pericardium, synovia! 

 sacs, etc. 



The serous fluids are of a pale amber color, somewhat viscid, alkaline, 

 coagulable by heat, and resemble the serum of the blood; their amount 

 is but small ; the pleural varies from 4 to 7 drachms ; the peritoneal from 

 I to 4 ounces ; the pericardial from I to 3 drachms. 



The synovia I fluid is colorless, alkaline, and extremely viscid, from the 

 presence of synovine. 



