38 PHYSIOLOGY FOR THE LABORATORY. 



c. The pulmonary artery leads from the base of the right 

 ventricle to the lungs. Look for it on the ventral side of 

 the heart between the two auricles. How far can you 

 trace it ? In what direction does it run ? Explain this 

 crossing. Does it carry arterial or venous blood ? Why 

 is it called an artery? (See G- in Fig. 3.) 



d. The aorta is the large tube leading from the left ven- 

 tricle. Trace it from the heart and find the arch where it 

 turns to go to the lower part of the body. (See H in Fig. 3.) 



e. The four pulmonary veins run from the lungs to the 

 left auricle. The two right pulmonary veins run close 

 along the dorsal surface of the right auricle. The two 

 left open at the extreme left of the auricle beneath the 

 arch of the aorta. (See I and J in Fig. 3.) 



/. Indicate the openings of the blood-vessels in your 

 sketches of the heart. 



g. Trace the path of the blood through the heart from 

 the superior and inferior vense cavse. 



h. Indicate in your sketches of the heart the path of the 

 blood through it. 



D. The Valves of the Heart. 



Materials. The heart of the calf. Water. 

 Apparatus. A bulb syringe. A glass graduate. 



I. THE TBICUSPID VALVE. 



Cut away most of the right auricle and with a bulb 

 syringe inject water or allow water from a faucet to flow 

 into the right ventricle. Notice the action of the valves 

 between the auricle and ventricle at the auriculo-ventricu- 

 lar orifice. Press on the ventricle to imitate its contrac- 



