CHAPTER XVIII 

 METABOLISM 



We have now studied the various organs which form secretions, 

 or substances which may be either devoted to a special use in the 

 body, or expelled as of no further use. These latter are known as 

 excretions. 



SECRETION 



Following, is an enumeration by way of review, of the principal 

 organs whose secretions are used in the body, with a partial list of 

 their functions: 



First. The epithelial cells of all surface membranes and cavities 

 should be included: 



Those of mucous membranes, secreting mucus. 



Those of serous membranes, secreting serum (as in the pleural, 

 pericardial and peritoneal cavities, and the subdural and sub- 

 arachnoid spaces of brain and spinal cord). 



Those of synovial membranes, secreting synovia. 

 The secreting cells of glands come next. 



The salivary, gastric and intestinal glands and pancreas secrete 

 saliva, gastric, intestinal and pancreatic juices. 



The liver secretes bile (and forms glycogen). 



The mammary glands secrete milk. 



The lacrimal glands secrete tears. 



The sebaceous glands secrete sebum. 

 Of the secretions of so-called ductless glands, or endocrin system. 



That of the pancreas influences glycogen-processes in the liver. 



That of the adrenal bodies increases blood pressure (contracting 

 arterioles) and retards the rate of cardiac action, also favors the 

 formation of sugar in the body. 



That of the thyroid body influences tissue metabolism, increases 

 cardiac action, and diminishes obesity. 



That of the parathyroids destroys toxins in the blood (or 

 inhibits their formation?). 



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