21. Erection of the penis results from ________.        

10. The dartos and cremaster muscles are important to the integrity of the male reproductive system. Which of the following best describes the role they play?        

40. The loading and unloading of O2 are facilitated by a change in the shape of red blood cells (RBC).

46. Which of the following is NOT a reason for O2 delivery?

25. The basic difference between spermatogenesis and oogenesis is that ________.        

26. Which structure is lined with simple squamous epithelium?        

6. Nasal conchae heat and moisten inhaled air, and reclaim heat and moisture during exhalation.

43. Which body system of a pregnant woman undergoes the most dramatic physiological changes during pregnancy?        

27. The term for pain associated with deficient blood delivery to the heart that may be caused by the transient spasm of coronary arteries is ________.        

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