110 



XXX 



(The following exercise is taken, by arrangement with the publisher, from 

 " An Introduction to Physiology," by W. T. Porter). 



361. Artificiai, Scheme of the Blood Circulation. 

 This scheme illustrates the mechanics of the circulation in 

 mammals. It consists of a pump (rubber bulb), a system of 

 elastic tubes, and a peripheral resistance. The inlet and out- 

 let tubes of the pump are furnished with valves which permit 

 a flow in one direction only. The peripheral resistance is the 

 friction which the liquid undergoes in flowing throug'h the 

 minute channels of a piece of bamboo (capillaries). To this 

 should be added the slighter resistance due to friction in the 

 rubber and glass tubes. 



Fig. 27. 



Diagram of Artificial Circulation Scheme (W. T. Porter). The bulb repre- 

 sents the ventricle j adjacent to it, on the left, the auriculo ventricular valves 

 are represented. The cross branch on the right of the bulb is for measuring in- 

 traventricular pressure. A little to the right of this are the " aortic " valves. 

 Immediately following is the arterial system with an arterial manometer inserted. 

 Just in front of the upright portion of the apparatus is the capillary field with a 

 side branch provided with a clamp for regulating peripheral resistance. From 

 the capillaries to the beaker is the venous system, which is also provided with a 

 manometer. 



The pump represents the left ventricle ; the valve in the 



inlet and outlet tubes the mitral and aortic valves, respect- 



vely ; the channels in the bamboo the resistance of the small 



