BLOOD VESSELS 



469 



by increasing the arterial pressure, drives more blood to 

 them. 



The circulation through the lungs is impeded in many 

 cases of heart disease, and especially in mitral stenosis 



INTRACRANIAL CIRCULATION 



PULMONARV CIRCULATION 



[ ABDOMINAL CIRCULATION 



— CIRCULATION m LIMBS 



Fig. 196. — Scheme of the Circulation, modified from Hill, to illustrate the 

 influence of the various extra-cardiac factors which maintain the flow 

 of Vjlood. 



(p. 410), and a condition of passive congestion is set up, 

 which may lead to h;eraorrhage from the lungs. 



3. Circulation in the Heart Wall. — The sympathetic fibres 

 are vaso- dilator not vaso-constrictor to the arterioles of the 

 coronary vessels and the administration of adrenalin dilates 

 these arterioles. 



4. Circulation in the Spleen. — Here the blood has to flow 

 through a labyrinth of large sinusoid capillaries in the 



