182 



ANATOMY AND PHYSIOLOGY 



This gives the effect of a beating in the arteries, which is called the 

 pulse. The pulse-rate corresponds with the heart-beat; therefore, 

 the rate and force of the heart's action are judged by means of the 

 pulse. 



The Heart Sounds 



The action of the heart causes certain sounds, named the first 

 and second. The first accompanies the sudden closure of the tri- 

 cuspid and mitral valves, as the ventricles contract. It is the 



UPPER ATTACHMENT 

 OF PERICARDIUM 



BRANCHES OF PUL 

 MONARY ARTERY 



AORTA--, 



BRANCHES OF 

 LMONARY ARTERY 

 -PULMONARY 

 ARTERY 



DIAPHRAGM PERICARDIUM 



RIGHT ATTACHMENT OF 

 VENTRICLE PERICARDIUM 

 TO DIAPHRAGM 



DIAPHRAGM 



FIG. 124. The heart in situ. The pericardium has been cut open in front, and 



reflected. (Testut.) 



systolic sound caused by the systole of the ventricles. The sec- 

 ond accompanies the sudden closure of the semilunar valves. It 

 is the diastolic sound, occurring with the diastole of the ventricles. 

 The first or systolic sound is the louder and larger, being due to 

 the contracting of muscle fibers as well as to closure of valves. 

 The second, diastolic sound is short and sharp, due to valve closure 

 only. The two sounds are compared to the spoken words lubb 

 dupp. 



