12. The funny current and pacemaker potential & 13. Modulating pacemaker rate

3 facts about the funny/I-f current

it is active at relatively negative voltages, it produces a slow depolarization, it produces a spontaneous depolarization

After repolarization _, then the threshold is reached _, next _, finally _ repolarizes the cell.

funny-current channels let Na+ in and K+ out (but Na at higher rates) to depolarize the cell, without an outside action potential, voltage-gated calcium channels open to generate the pacemaker-cell action potential, potassium

The _ nervous system can change the rate at which pacemaker cells reach threshold

without replacing their intrinsic rhythm

autonomic

How does sympathetic input change the HR?

it can raise the pacemaker-cell membrane potential and increase the slope of the pacemaker potential