i8o 



A MANUAL OF PHYSIOLOGY 



the piston is raised, the semilunar valve is seen to be closed and the 



auriculo-ventricular valve to be opened. For comparison a human 



heart with a valvular lesion might be used. 



(2) With the sheep's or dog's heart provided, perform the following 



experiments : 



(a) Open the pericardium and notice how it is reflected around 



the great vessels at the base of 

 the heart. Distinguish the pul- 

 monary artery, the aorta, the 

 superior and inferior venae cavse, 

 and the pulmonary veins. The 

 trachea and portions of the lungs 

 may also be attached. If so, 

 remove them carefully without 

 injuring the heart. 



(I)} Take two wide glass tubes, 

 drawn slightly into a neck at one 

 end. One of the tubes should 

 be about 10 cm. long, and the 

 other about 50 cm. Tie the 

 short tube A firmly by its neck 



FIG. 67. ARRANGEMENT TO ILLUSTRATE ACTION OF CARDIAC VALVES IN 

 THE HEART OF AN Ox (GAD). 



C, glass window in left auricle ; D, window in aorta ; E, tube inserted through apex 

 of heart into left ventricle and connected with pump P ; A, side tube on E, through 

 which wires are connected with a tiny incandescent lamp in the ventricle ; W, water in 

 bottle B ; T, T' tubes. 



into the superior vena cava, the long tube B into the pulmonary 

 artery. Ligature the inferior vena cava. Connect A by a small 

 piece of rubber tubing with a funnel supported in a ring on a stand. 

 Pour water into the funnel till the right side of the heart is full. It 



