Briefly describe the events leading a conducting cell to an action potential and choose the method of depolarization: sodium or calcium. Choose 4 answers.
a) A few sodium channels open, voltage-gated potassium channels close, voltage-gated (slow) calcium channels begin opening, depolarizing the cell to the threshold potential.
b) Rapid depolarization due to voltage-gated fast sodium channels opening and the membrane being permeable to sodium.
c) Voltage-gated (fast) calcium channels close, voltage-gated potassium channels open for rapid repolarization.
d) At +30 mV, fast sodium channels close and slow calcium channels open, allowing calcium ions to enter the sarcoplasm from the extracellular fluid.
e) When slow calcium channels close, slow potassium channels open, resulting in a rush of potassium ions out of the cell for rapid repolarization to resting potential.
f) Voltage-gated (fast) calcium channels open for rapid depolarization.
g) Depend on sodium influx for depolarization.
h) Depend on calcium influx for depolarization.