Objective 99: 1

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Objective 100: 10

Fig a. Conducting system of the heart 11

Fig Sequence of impulse conduction through the heart. 12

Fig. 20-4b. Direction of ventricular fibers twists the heart during contraction. 13

Objective 101: 14

Fig Elastic and muscular arteries 15

Fig Arterioles and capillary bed 16

Fig Venules and veins 17

Objective 102: 18

Fig Valves in the veins promote blood flow back to the heart. 19