94 ANATOMY AND PHYSIOLOGY FOR NURSES 



THE ARTERIAL SYSTEM 



The arteries are the cylindric tubes that convey the 

 blood from the ventricles of the heart to every part of the 

 body. They are capable of preserving their form at all 

 times. In ancient times, the arteries being found empty 

 after death and still preserving their cylindric form, were 

 believed to contain air. This theory was held until the 

 time of Harvey, who discovered the circulation of the 



blood and presented it to 

 the world as we now teach 

 it. 



As has been said, the 

 main artery of the body 

 is the aorta; from this all 

 the arterial tissues derive 

 their origin. This will be 

 described further on. The 

 communications of arteries 

 are numerous. They do 

 not terminate in veins, but 

 are connected with the lat- 

 ter by an intermediate sys- 

 tem of vessels, called capil- 

 laries (from capillus, a hair) . 

 So numerous are these vessels that the slightest injury, 

 such as a needle-prick, implicates many of these vessels 

 and they bleed profusely. 



The capillaries, as has been said, are the intermedi- 

 ate vessels between the arteries and veins. It is in these 

 vessels that the most important functions or. changes of the 

 blood occur the change from arterial to venous blood. 

 Here the phenomena of oxidation and calorification take 

 place, and it is from this system that the endless variety 

 of materials is supplied to the tissues of the body for 

 nutrition and for glandular secretions. 



FIG. 49. Diagra 



(Morrow). 



m of capillaries 



