biomed action potential

Action Potential

A rapid, temporary change in the electrical membrane potential of a cell, which serves as a signal to transmit information along an axon.

Resting Membrane Potential

The stable voltage across a cell membrane when it is not being stimulated, typically measured at approximately -70 \text{ mV}.

Threshold Potential

The specific voltage level, usually around -55 \text{ mV}, that must be reached for an action potential to be triggered.

Depolarization

The phase where voltage-gated Na^+ channels open, causing an influx of sodium ions and making the inside of the cell more positive.

Repolarization

The phase where Na^+ channels close and voltage-gated K^+ channels open, allowing potassium ions to exit the cell to restore a negative internal charge.

Hyperpolarization

A brief period following repolarization where the membrane potential becomes more negative than the resting potential due to slow-closing K^+ channels.

All-or-None Principle

The concept that an action potential will occur at full strength if the threshold is reached, and will not occur at all if the stimulus is below threshold.

Absolute Refractory Period

The interval during which a second action potential cannot be initiated, regardless of the stimulus strength, because Na^+ channels are inactivated.

Saltatory Conduction

The rapid propagation of an action potential along a myelinated axon where the signal jumps between the Nodes of Ranvier.

Sodium-Potassium Pump

An active transport mechanism that moves $3$ Na^+ ions out and $2$ K^+ ions in to maintain the chemical gradients and resting potential.

Action Potential

A rapid, temporary change in the electrical membrane potential of a cell, which serves as a signal to transmit information along an axon.

Resting Membrane Potential

The stable voltage across a cell membrane when it is not being stimulated, typically measured at approximately -70 \text{ mV}.

Threshold Potential

The specific voltage level, usually around -55 \text{ mV}, that must be reached for an action potential to be triggered.

Depolarization

The phase where voltage-gated Na^+ channels open, causing an influx of sodium ions and making the inside of the cell more positive.

Repolarization

The phase where Na^+ channels close and voltage-gated K^+ channels open, allowing potassium ions to exit the cell to restore a negative internal charge.

Hyperpolarization

A brief period following repolarization where the membrane potential becomes more negative than the resting potential due to slow-closing K^+ channels.

All-or-None Principle

The concept that an action potential will occur at full strength if the threshold is reached, and will not occur at all if the stimulus is below threshold.

Absolute Refractory Period

The interval during which a second action potential cannot be initiated, regardless of the stimulus strength, because Na^+ channels are inactivated.

Saltatory Conduction

The rapid propagation of an action potential along a myelinated axon where the signal jumps between the Nodes of Ranvier.

Sodium-Potassium Pump

An active transport mechanism that moves 3 Na^+ ions out and 2 K^+ ions in to maintain the chemical gradients and resting potential.

Voltage-Gated Na^+ Channels

Transmembrane proteins that open rapidly when the threshold potential of -55 \text{ mV} is reached, allowing sodium ions to rush into the cell and cause depolarization.

Voltage-Gated K^+ Channels

Transmembrane proteins that open slowly at the peak of depolarization, allowing potassium ions to exit the neuron to initiate repolarization.

Nerve Impulse

The propagation of an action potential along an axon, which involves the sequential opening and closing of voltage-gated channels to transmit electrical signals.

Action Potential

A rapid, temporary change in the electrical membrane potential of a cell, which serves as a signal to transmit information along an axon.

Resting Membrane Potential

The stable voltage across a cell membrane when it is not being stimulated, typically measured at approximately -70 \text{ mV}.

Threshold Potential

The specific voltage level, usually around -55 \text{ mV}, that must be reached for an action potential to be triggered.

Depolarization

The phase where voltage-gated Na^+ channels open, causing an influx of sodium ions and making the inside of the cell more positive.

Repolarization

The phase where Na^+ channels close and voltage-gated K^+ channels open, allowing potassium ions to exit the cell to restore a negative internal charge.

Hyperpolarization

A brief period following repolarization where the membrane potential becomes more negative than the resting potential due to slow-closing K^+ channels.

All-or-None Principle

The concept that an action potential will occur at full strength if the threshold is reached, and will not occur at all if the stimulus is below threshold.

Absolute Refractory Period

The interval during which a second action potential cannot be initiated, regardless of the stimulus strength, because Na^+ channels are inactivated.

Saltatory Conduction

The rapid propagation of an action potential along a myelinated axon where the signal jumps between the Nodes of Ranvier.

Sodium-Potassium Pump

An active transport mechanism that moves 3 Na^+ ions out and 2 K^+ ions in to maintain the chemical gradients and resting potential.

Voltage-Gated Na^+ Channels

Transmembrane proteins that open rapidly when the threshold potential of -55 \text{ mV} is reached, allowing sodium ions to rush into the cell and cause depolarization.

Voltage-Gated K^+ Channels

Transmembrane proteins that open slowly at the peak of depolarization, allowing potassium ions to exit the neuron to initiate repolarization.

Nerve Impulse

The propagation of an action potential along an axon, which involves the sequential opening and closing of voltage-gated channels to transmit electrical signals.

Sodium-Potassium (Na^+/K^+) Pump Function

To use ATP to maintain the concentration gradients of sodium and potassium, ensuring the cell remains excitable and can restore its resting potential after an action potential.

Potassium (K^+) Leak Channels

Channels that are always open and allow potassium to exit the cell down its concentration gradient, playing a primary role in establishing the resting membrane potential.