17. Heart beats are autorhythmic. Which specialized cardiac muscle cells act as a pacemaker, determining the rate of heartbeat?
(A) sinoatrial node
(B) atrioventricular node
(C) His bundle
(D) Purkinje fibers
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統計: A(8), B(1), C(0), D(0), E(0) #3839952
統計: A(8), B(1), C(0), D(0), E(0) #3839952