472 CIRCULATION OF BLOOD AND LYMPH. 



Potain. The same observer reports observations upon the effect 

 of meals, of baths, of posture, the diurnal rhythm, etc.* 



The effect of meals is particularly instructive in that it illustrates 

 admirably the play of the compensatory mechanisms of the circu- 

 lation by means of which the heart and the blood-vessels are ad- 

 justed to each other's activity. During a meal there is a dilatation 

 of the blood-vessels in the abdominal area, or, as it is frequently 

 called in physiology, the splanchnic area, since it receives its 

 vasomotor fibers through the splanchnic nerve. The natural 

 effect of this dilatation, if the other factors of the circulation 

 remained constant, would be a fall of pressure in the aorta and a 

 diminution in blood-flow to other organs, such as the skin and the 

 brain. This tendency seems to be compensated, however, by an 

 increased output of blood from the heart. Observations with the 

 sphygmomanometer show that after full meals there is a marked 

 increase in the pulse pressure, indicating a more forcible beat of the 

 heart. So far as the effect on the heart is concerned, the result of a 

 meal is similar to that of muscular exercise, and this reaction may 

 account for the fact, not infrequently observed, that in elderly 

 people whose arteries are rigid an apoplectic stroke may follow a 

 heavy meal. 



* Erlanger and Hooker. "The Johns Hopkins Hospital Reports," voL 

 xii., 1904. 



