DILUENTS 63 



and hasten removal of deposits. In the form of watery 

 vapour, simple or medicated emollients relieve irritability 

 and congestion of the respiratory mucous membrane. Not 

 only do they reduce tension and relax tissues to which they 

 are immediately applied, but, acting on adjacent vaso- 

 motor centres, they dilate collateral blood-vessels ; and 

 mainly in this way fomentations and poultices relieve 

 irritation and inflammation of the throat, lungs, and other 

 deep-seated organs. In the earlier stages of inflammation 

 they promote resolution ; and in all stages they relieve 

 heat, tension, pain, and spasm. Although serviceable for 

 softening and cleansing septic wounds, they should not be 

 used for wounds in process of healing by first intention or 

 adhesion. 



DILUENTS are allied to demulcents and emollients, are 

 liquid or solid substances used along with more active 

 agents in order to diminish their activity. They include 

 most demulcent drugs. 



MEDICINES ACTING ON MUSCLE 

 ACTION OF MEDICINES ON MUSCLE 



The three varieties of muscle, striped or voluntary, un- 

 striped or involuntary, and cardiac muscle, are affected quite 

 differently by drugs, and must be considered separately. 

 The chief characteristic of muscle is the power of contraction 

 when stimulated. The striped muscles are all connected 

 with the central nervous system by means of nerve fibres of 

 two kinds, the one sensory or afferent, conveying impres- 

 sions from the muscle to the nerve centre, the other motor 

 or efferent, transmitting impulses from the centre to the 

 muscle. These motor impulses result in contraction of the 

 muscle, and these contractions and the succeeding relaxa- 

 tions (passive) are accompanied by chemical changes in the 

 muscle which set free the necessary energy. Oxygen is used 

 up whilst sarcolactic acid and carbon dioxide are formed. 

 These waste products, and the accompanying fatigue conse- 

 quent on repeated violent contractions, can be removed 



