12. The funny current and pacemaker potential

Pacemaker cells have a membrane current that is active at _ and _. This is called the _.

relatively negative voltages, produces slow, spontaneous depolarization, funny current or I-f current

1. After repolarization, funny-current channels allow _.

inward current that slowly depolarizes the pacemaker cell

2. The pacemaker potential reaches threshold without _.

requiring an outside action potential

3. _ channels open and generate the _.

Voltage-gated calcium, pacemaker-cell action potential

4. _ currents _ the cell, after which the cycle begins again.

Potassium, repolarize

The pacemaker action potential is _ at threshold, whereas the pacemaker potential before threshold is driven largely by inward _ through _.

calcium-based, sodium current, funny-current channels