K channels are open 2. K channels slowly close that causes cell to depolarize 3. This voltage activates K channels that causes the repolarization. Because it is striated, cardiac muscle is most akin to sk muscle. High number of capillaries and mitochondria.
Fibers are shorter than sk muscle are electrically linked by gap junction at the intercalated disk.
EC - coupling is similar to sk muscle because of organization of contractile elements. Cardiac cells can be divided into two subdivision. Conducting cells - Have pacemaker potentials, a prepotential that brings about an action potential. The pacemaker cells reside in specialized regions of the heart and are responsible for bring the contracting cells to threshold. Pacemaker cells lack a substantial K conductance and have a high Na permeability, that tends to keep it rather depolarized.