306 



THE CIRCULATION IN THE BLOOD-VESSELS [CII. XXTI. 



Stimulation of this nerve affects the vaso-motor centre in such a way 

 that the normal constrictor impulses that pass down the vaso-con- 

 strictor nerves are inhibited. The fall of pressure is very slight after 

 section of the splanchnic nerves, showing that the splanchnic area is 

 the part of the body most affected. The normal function of this 



B.P. 



FIG. 263. Tracing of arterial blood-pressure showing the effect of stimulating the central end of the Depressor nervr 

 a cat. The letters prefixed to the various lines have the same meaning as in tig. 2(37. (Sherrington.) 



nerve is to adapt the peripheral resistance to the heart's action : if 

 the constriction of the arterioles is too high for the heart to overcome, 

 an impulse by this nerve to the vaso-motor centre produces reflexly 

 a lessening of the peripheral resistance. 



N.B. The term depressor should be carefully distinguished from 

 inhibitory ; stimulation of the peripheral end of the vagus produces 

 a fall of blood pressure due to inhibition (slowing or stoppage) of the 

 heart (see figs. 246 and 247); stimulation of the central end of the 



