THE CIRCULATORY OR VASCULAR SYSTEM 93 



and the external iliac, the internal supplying the pelvic 

 tissues and the external the lower extremities. 



The Heartbeat. The heart in the healthy adult beats 

 from 60 to 80 times in a minute; in children and infants 

 the beat is more frequent, varying from 100 to 150 times 

 in a minute. 



Arteries are all characterized by a vibrating action, 

 called pulsation, which corresponds to the working of the 

 heart. This pulsation is in part dependent upon the 

 action of the latter organ, but partly also on a similar 

 power of contraction possessed by the arteries themselves. 



The motion of the blood in the arteries is always in a 

 direction away from the heart, and this fluid is propelled 

 in these vessels by the pulsating force just described. 



The systemic circulation is made up of two chief divis- 

 ions the arterial and the venous systems. In addition 

 to these, two subsidiary systems are described the pul- 

 monary and the portal. We will describe first the arterial 

 system, prefacing our remarks by a brief description of the 

 arteries themselves. 



This diagram, taken from Gray, shows the various 

 parts and openings of the heart. The nurse will do well to 

 make herself familiar with their names, and, by frequent 

 reference to the illustrations, seek to learn their location: 



Openings 

 in the 

 heart : 



Superior vena cava. Relics of fetal ( Annulus ovalis. 



Inferior vena cava. structures : \ Fossa ovalis. 



Coronary sinus. 



Foramina Thebesii. 



Auriculoventricular opening. Musculi pectinati. 



Pulmonary artery. 



Pulmonary veins. Valves { Eustachian - 



Aorta. ' I Coronary. 



Auriculoventricular (right). 



Valves (right side] : { Tricus P id - Va i ves (!efl side] , / Mitral. 



I Semilunar. ' \ Semilunar. 



