Blood flows more slowly in the arterioles than in the artery that supplies them because the arterioles a. have thoroughfare channels to venules that are often closed off, slowing the flow of blood. b. have sphincters that restrict flow to capillary beds. c. are narrower than the artery. d. collectively have a larger cross-sectional area than does the artery.

Pulse is a direct measure ofa. blood pressure.b. stroke volume.c. cardiac output.d. heart rate.

When the doctor listened to Janet's heart, he heard 'lub-hiss, lub-hiss' instead of the normal 'lub-dup' sounds. The hiss is most likely due to _________ . (Explain your answer.)a. a defective atrioventricular (AV) valveb. a damaged pacemaker (SA node)c. a defective semilunar valved. high blood pressure

Paul's blood pressure is 150/90. The 150 indicates _________ , and the 90 indicates _________ . a. pressure in the left ventricle; pressure in the right ventricle b. pressure during ventricular contraction; pressure during heart relaxation c. systemic circuit pressure; pulmonary circuit pressure d. pressure in the arteries; pressure in the veins

Which of the following initiates the process of blood clotting? a. damage to the lining of a blood vessel b. conversion of fibrinogen to fibrin c. attraction of white blood cells to a site of infection d. conversion of fibrin to fibrinogen

Explain why a person who survives a myocardial infarction might need to have an artificial pacemaker implanted.

During exercise, the cardiovascular system must supply muscles with large amounts of oxygen and fuel and get rid of a lot of wastes. How do the cardiovascular systems of athletes respond to prolonged exercise?Researchers used echocardiography, a sonogram of the heart, to estimate the mass of the left ventricle in current athletes, non-athletes, and ex-athletes. The data are graphed below (***meansP<0.001, and the P value comparing non-athletes and ex-athletes is >0.05). What conclusion can be drawn from the graph?

Some babies are born with a small hole in the wall between the left and right ventricles. How might this affect the oxygen content of the blood pumped out of the heart into the systemic circuit?

During exercise, the cardiovascular system must supply muscles with large amounts of oxygen and fuel and get rid of a lot of wastes. How do the cardiovascular systems of athletes respond to prolonged exercise?Explain the advantage of the observed difference between current athletes and non-athletes in the graph shown here.