ARTERIES 3< 



ARTERIES, ar'teriz, are tubes, or vessels, 

 through which blood is pumped by the heart 

 to various parts of the body. With the veins 

 and capillaries they form the pipe-lines of the 

 great circulatory system, of which the heart 

 is the cent nil pumping station. The details 

 of the process by which the blood is sent to all 

 parts of the body may be found in these 

 volumes under the headings HEART and CIRCU- 

 LATION OF THE BLOOD. The system of arteries 

 begins at the heart. A large artery called the 

 (which see) rises from the left ventricle 

 and carries pure red blood to the tissues of the 

 body; from the right ventricle rises the pul- 

 monary artery, which carries impure blood 

 to the lungs. The aorta extends upward from 

 the heart and then curves downward so as to 

 form an arch. In the region of the abdomen 

 it divides into the right and left iliac arteries; 

 these are continued into the lower extremities, 

 where they are known as the right and left 

 femoral arteries. Branches of the femoral 

 arteries form a network through the lower 

 limbs. The right and left subclavian arteries 

 spring from the aorta and extend to the shoul- 

 ders, being continued in the brachial arteries of 

 the arms. The head is nourished by two 

 carotid arteries, and the heart by the coronary 

 arteries. 



The large arteries have three coats; these 

 are a tough outer elastic coat, a middle mus- 

 cular coat, and a smooth, thin, inner coat. As 

 arteries proceed from the heart they divide 

 and subdivide into tubes which continually 

 grow smaller until they become tiny capil- 

 laries (which see). These latter have but one 

 coat, for their walls are merely an extension 

 of the thin inner layer of the arteries. Blood 

 from a cut artery flows out in spurts or jets, 

 and is bright red in color. For methods of 

 checking the flow of blood from a cut artery 

 see BLEEDING, subhead Arterial Bleeding. 



Hardening of the Arteries. Physicians de- 

 man is as old as his arteries." 

 Changes in the composition of the blood, con- 

 <ms use of alcoholic liquors, overeating, 

 >nic indigestion, over-work of the heart, in- 

 door occupations without sufficient exercise, 

 worry, lead poisoning and disease of the kid- 

 neys cause hardening of the arteries. No rera- 

 has been found for this disease, which 

 oves fatal. By avoiding the causes 

 people usually live to a good old age with- 

 out contracting the disease. The principal 

 cause of hardening of the arteries in present- 

 day American life is overeating of albuminous 



I ARTESIAN WELL 



food, especially flesh, and the use of alcoholic 

 drinks and tobacco. People who live tem- 

 perately and who have reasonably regular 

 habits of exercise and sleep rarely suffer from 

 hardening of the arteries. The disease is never 

 found in childhood or youth. 



Blood pressure, which depends on the force 

 of the heartbeat and on the character of the 

 arteries, is an important factor in determining 

 this disease. The small arteries are sur- 

 rounded by muscle fiber, which, by contracting, 

 can put the blood under severe pressure. 

 Blood pressure is measured by several devices, 

 which are operated on the following principle: 

 By means of an inflatable rubber bag fastened 

 around the upper part of the arm, the artery 

 is compressed, the pressure being increased 

 until the pulse at the wrist ceases to be felt. 

 The point at which this occurs is noted on the 

 mercury scale. When the tension is very high 

 the blood pressure may read 300 millimeters, 

 whereas it is normally 120 to 150. If a person 

 finds that his blood pressure is increasing, which 

 is evidence of hardening of the arteries, he 

 should at once adopt a simple, rational pro- 

 gram with temperance in everything and he can 

 arrest the progress of the disease. W.A.E. 



ARTESIAN, ahrte'zhan, WELL, a well 

 formed by boring or drilling into a layer of 

 porous rock which brings water from some 



ARTESIAN WELL 



Upper: Cross section showing underground 

 relations of a water-bearing sandstone. A shows 

 the overlying moss of clay, B, the stratum of 

 sandstone, sand, or gravel- through which 

 water flows, and C. the underlying impervious 

 toer: Profile across an artesian basin 

 showing hydrostatic grade, which determines the 

 "head" or height to which the water will rise. 

 >ll,i (in.- Is the land profile; the broken lin- 

 iii- Ic grade. In the diagram A Is the 



overlying clay: B, the sandstone stratum ; ('. th 

 granit< . <>r Impervious rock : * shows the point 

 of Intak.'. and y the outlet or spring; at any 

 point below the dotted line at a y, or hydrostatic 

 grade, the water will flow, while at points above 

 line, such as b. there will be no flow. 



higher point. Such a layer, or stratum, is 

 shown at B, in the upper illustration. The rain 

 falls upon it where it is exposed, and seeps 



