Neuronal Action Potential Dynamics

Dr. Alice explains the refractory period in neurons, focusing on absolute and relative refractory periods. The absolute refractory period is when no new action potentials can be generated due to inactivated sodium channels. The relative refractory period allows for some messages if they are strong enough, as sodium channels return to a resting state but potassium channels remain open. The video covers the mechanisms and challenges of these periods, emphasizing the role of sodium and potassium channels in neuron communication.

What is the primary reason a neuron cannot receive another message during the refractory period?

• The neuron is damaged.

• The neuron is not connected to others.

• The membrane charge is already high.

• The neuron is too small.

During the absolute refractory period, what is the state of the voltage-gated sodium channels?

• They are closed.

• They are inactivated.

• They are partially open.

• They are fully functional.

In the relative refractory period, what is required for a neuron to respond to a message?

• A strong message.

• A message from multiple neurons.

• A weak message.

• No message is needed.

What happens to the membrane charge during the depolarizing phase?

• It fluctuates randomly.

• It remains constant.

• It increases.

• It decreases.

Which channels are responsible for bringing the membrane charge back down during repolarization?

• Calcium channels.

• Chemically gated sodium channels.

• Voltage-gated potassium channels.

• Voltage-gated sodium channels.

What is the resting membrane potential of a neuron?

• -30 millivolts

• 30 millivolts

• 0 millivolts

• -70 millivolts

Why is it difficult for a neuron to reach threshold during the relative refractory period?

• The neuron is in a resting state.

• The neuron is too far from the stimulus.

• Potassium channels are open.

• Sodium channels are closed.

What analogy is used to describe the difficulty of reaching threshold during the relative refractory period?

• Climbing a mountain.

• Swimming upstream.

• Skydiving without a parachute.

• Running a marathon.

What is the main problem during the absolute refractory period?

• Voltage-gated sodium channels.

• Calcium channels.

• Voltage-gated potassium channels.

• Chemically gated sodium channels.

What is the main problem during the relative refractory period?

• Voltage-gated sodium channels.

• Voltage-gated potassium channels.

• Chemically gated sodium channels.

• Calcium channels.