Action Potential

What occurs during Phase 0 of myocytic potential?

Rapid inward rush of Na+ through fast channels and slow influx of Na+ and Ca+ until it reaches -90 mV inside the cell.

What is the key event in Phase 1 of myocytic potential?

Sudden closure of fast Na+ channels and potassium deflux.

Describe Phase 2 of myocytic potential.

A plateau phase where there is a balance between influx of Ca+ and outflow of K+.

What happens during Phase 3 of myocytic potential?

Closure of Ca+ channels and continued K+ outflow.

During Phase 4 of myocytic potential, what maintains the resting membrane potential?

Na+ and Ca+ channels close while K+ slowly leaks out, making the inside of the cell negative relative to the outside.

What is the significance of the 'PISO' concept in myocytic potential?

Potassium IN Sodium OUT describes the movement of ions affecting resting membrane potential.

What characterizes Phase 4 of pacemaker potential?

Unstable resting membrane potential due to Na+ influx through Funny Na+ channels and Ca+ leak.

What initiates depolarization in Phase 0 of pacemaker potential?

Reaching -40 mV triggers the opening of L-type Ca+ channels leading to rapid depolarization.

What happens during Phase 3 of pacemaker potential?

Potassium channels open and L-type Ca+ channels close, resulting in repolarization.

How does the funny Na+ channel influence pacemaker potential?

It causes slow depolarization due to Na+ and Ca+ leak until reaching the threshold of -40 mV.