Physiology

at a Glance

Jeremy P. T. Ward, Roger W. A. Linden

Multiple Choice: Chapter 22 Initiation of the heart beat and excitation-contraction coupling

Question 22.1 Action potentials in ventricular muscles

A are identical to those in skeletal muscles except for the duration of the action potential
B have a plateau phase caused by the delay in the opening of K+ channels
C are initiated when ventricular myocytes are depolarized to a threshold potential of −50 mV
D have a refractory period which prevents another action potential being initiated until the muscle relaxes