48. If the AV node is not working correctly, a surgeon should surgically implant the heart with an artificial pacemaker.

45. The ___ is where sperm mature and are stored until needed.

49. Angina pectoris is thoracic pain caused by a fleeting deficiency in blood delivery to the myocardium, with resulting decreased oxygen being delivered to the cells. Because nitroglycerin acts as a vasodilator (similar to nitric oxide), blood flow is increased, promoting the delivery of oxygen to the cells

16. Which of the following is least involved in pulmonary circulation?        

45. Right atrium to left ventricle to pulmonary semilunar valve to pulmonary arteries to lungs to pulmonary veins (pulmonary circuit pump); left atrium to right ventricle to aorta to body tissues to venae cavae (systemic circuit pump).

50. As pregnancy continues, the increasing bulkiness of the anterior abdomen changes the woman’s center of gravity, possibly causing an accentuated lumbar curvature called ________.        

11. The ability of sperm cells to move along the ductus deferens is due to ________.        

46. The ___ of the sperm contains the mitochondria which make ATP to power the swimming.

20. If a woman has just ended her menstrual phase, when is she most likely to ovulate?        

22. Hemorrhage with a large loss of blood causes ________.