Flashcards in Cardiac APs Deck (6):
Significance of IK1 Channels:
- These create the INWARD rectifier current.
• Does not "gate" like other channels:
- passes + charge more easily into the cell than out of the cell.
• Functions to maintain resting membrane potential by making minor changes in potential
○ Either influx or efflux of potassium
Significance of If currents:
• HCN tetramer
• Funny current: Considered "funny" because it is turned off at depolarized potentials and on at hyperpolarized potentials
○ Ability to be activated at hyperpolarization is important in pacemaker cells w/o neuronal stimulus b/c it allows AP firing without stimulus from innervation
• Permeable to both Na and K
other cells have pacemaker activity and can become pacemakers, but that SA nodal firing suppresses this activity. Other sites are:
• Can be located in:
1. AV node and purkinje fibers
2. Ectopic pacemaker cells:
Why is the SA node the dominant pacemaker activity?
it has the highest intrinsic rate of automaticity
Ectopic pacemaker cells:
Can be cells that display automaticity (like SA node) because of hypoxic conditions