Voltage gated Na channels

Dr. Morton explains the structure and function of voltage gated sodium channels (VGSC), detailing their anatomy, conformational states, and role in action potentials. VGSCs are transmembrane proteins that open in response to changes in membrane potential, allowing sodium ions to flow in. They have three states: closed, open, and inactive. The video also covers the process of repolarization and the role of VGSCs in neurons and cardiac cells.

What is the primary function of the activation gate in a voltage gated sodium channel?

• To allow potassium ions to enter the cell

• To maintain the resting membrane potential

• To open in response to membrane depolarization

• To close when the cell is hyperpolarized

In the closed state, what prevents sodium ions from entering the cell?

• Potassium channels are open

• The inactivation gate is open

• The activation gate is closed

• The membrane is hyperpolarized

What triggers the transition of a voltage gated sodium channel from closed to open state?

• A decrease in external sodium concentration

• An increase in internal potassium concentration

• A depolarization to -55 millivolts

• A hyperpolarization to -90 millivolts

During the open state, what is the result of sodium influx?

• The membrane potential becomes more negative

• The membrane potential depolarizes to positive 30 millivolts

• Potassium ions are pumped into the cell

• The inactivation gate opens

What happens to the inactivation gate during the inactive state?

• It closes, preventing sodium entry

• It opens, allowing potassium exit

• It remains open

• It closes, allowing sodium entry

How is the resting membrane potential restored after depolarization?

• By the influx of calcium ions

• By the influx of sodium ions

• By the closure of all ion channels

• By the efflux of potassium ions

What role does the sodium-potassium pump play in ion restoration?

• It pumps potassium ions out of the cell

• It pumps sodium ions into the cell

• It pumps sodium ions out and potassium ions into the cell

• It pumps calcium ions into the cell