010 Repolarization: Phase 2 of the Action Potential

Leslie Samuel explains the second phase of the action potential, repolarization. He emphasizes the importance of understanding the first phase, depolarization, where sodium ions rush into the cell, making the membrane potential more positive. The video then introduces potassium ions, which have a positive charge and are abundant inside the cell. When the membrane potential becomes sufficiently positive, voltage-gated potassium channels open, allowing potassium ions to exit the cell. This outflow makes the membrane potential more negative, a process known as repolarization. Leslie encourages viewers to ask questions and promises to address them in future videos.

What is the first phase of the action potential where sodium ions play a crucial role?

• Depolarization

• Repolarization

• Resting potential

• Hyperpolarization

What do the blue marbles in the action potential simulator represent?

• Chloride ions

• Potassium ions

• Calcium ions

• Sodium ions

Why do potassium ions want to leave the cell during repolarization?

• To increase the cell's energy

• To make the membrane potential more negative

• To balance the sodium ion concentration

• To make the membrane potential more positive

What triggers the opening of voltage-gated potassium channels?

• The closing of sodium channels

• A negative membrane potential

• A very positive membrane potential

• The presence of calcium ions

What is the main outcome of the repolarization phase in action potentials?

• The cell releases neurotransmitters

• The cell becomes hyperpolarized

• The cell becomes more positive

• The cell returns to its resting state