014 The Journey Down the Axon

In this video, Leslie Samuel explains how action potentials travel down the axon of a neuron. The video covers the structure of a neuron, focusing on the soma, axon, and axon hillock. It describes the role of voltage-gated sodium channels in generating action potentials and how sodium ions move to propagate the signal. The video also addresses why action potentials travel in one direction due to the refractory period of sodium channels. The session concludes with an invitation for viewers to ask questions.

What is the initial part of the neuron where voltage-gated channels are first found?

• Axon terminals

• Soma

• Axon hillock

• Dendrites

What triggers the opening of voltage-gated sodium channels?

• Decrease in membrane potential

• Increase in membrane potential

• Presence of potassium ions

• Absence of calcium ions

What happens to sodium ions when they enter the neuron?

• They move along the axon

• They become inactive

• They stay in one place

• They exit the neuron immediately

What is the effect of sodium ions entering the neuron on membrane potential?

• It fluctuates randomly

• It becomes more negative

• It remains unchanged

• It becomes more positive

Why does the action potential travel in only one direction?

• Due to the presence of myelin sheath

• Because sodium ions can only move forward

• Due to the refractory period of sodium channels

• Because potassium channels block the reverse path

What must happen before a voltage-gated sodium channel can be stimulated again?

• It must be depolarized

• It must be inactivated

• It must be reset to closed

• It must be hyperpolarized

What is the term used for the period when sodium channels cannot be stimulated again?

• Threshold period

• Refractory period

• Active period

• Resting period