190 



A MANUAL OF PHYSIOLOGY 



surface, with a kind of simmering movement suggestive of a boiling 

 pot (delirium cordis, fibrillar contraction). Now kill the animal by 

 stopping the artificial respiration. Observe how long the heart 

 continues to beat, and which of its divisions stops last. 



(k) Make a dissection of the cervical sympathetic up to the superior 

 cervical ganglion, and down through the inferior cervical ganglion 

 to the stellate or first thoracic ganglion. Make out the annulus of 

 Vieussens and the cardiac sympathetic (accelerator) branches going 

 off from the annulus or the inferior cervical ganglion to the cardiac 

 plexus (Fig. 62, p. 148). 



14. Action of the Valves of the Heart. (i) Study the action of 

 the valves of the ox-heart, connected with the pump P and bottle 

 B in the artificial scheme, as shown in Fig. 84. The cavity of the 

 heart is illuminated by means of a small electric lamp, the wires 

 of which pass in at A. When the piston of the pump is pushed down, 



water is forced through 

 the aorta D along the tube 

 T into the bottle, and flows 

 back again into the left 

 auricle by the tube T'. 

 During each stroke of the 

 pump the auriculo - ven- 

 tricular valve is seen 

 through the glass disc in- 

 serted into C to close, and 

 the semilunar valve is seen 

 through the glass in D to 

 open. When 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, per- 

 form the following experi- 

 ments : 



(a) Open the pericar- 

 dium and notice how it is 



reflected around the great vessels at the base of the heart. Distin- 

 guish the pulmonary artery, the aorta, the superior and inferior 

 venae cavae, and the pulmonary veins. The trachea and portions of 

 the lungs may also be attached. If so, remove them carefully 

 without injuring the heart. 



(b) 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 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 will 

 escape from the left azygos vein, which must be tied. Put on any 

 additional ligatures that may be needed to render the heart water- 

 tight. Support B in the vertical position by a clamp. Fill the 



FIG. 85. DIAGRAM OF VALVES OF THE HEART. 



The valves are supposed to be viewed from 

 above, the auricles having been partially re- 

 moved. A, aorta with semilunar valve ; D, posi- 

 tion of corpora Arantii ; P, pulmonary artery ; 



B, wall of left auricle ; M, mitral valve, with 

 i and 2, its posterior and anterior segments ; 



C, wall of right auricle ; T, tricuspid valve, with 

 i, its posterior ; 2, its anterior ; and 3, its external 

 segment. 



