Conduction of Nerve Impulse (Action Potential)
Details the sequence of events during an action potential, including depolarization, repolarization, and its propagation along the axon.
What is Conduction of Nerve Impulse (Action Potential)?
The electrical potential difference across the plasma membrane of a neuron when it is not transmitting a nerve impulse, typically around -70mV.
Key points
- Explain the ionic basis of resting membrane potential.
- Describe the sequence of events during an action potential (depolarization, repolarization, hyperpolarization).
- Identify the roles of voltage-gated Na+ and K+ channels.
- Understand the concept of threshold potential and refractory periods.
Common exam trap
Confusing depolarization and repolarization phases.
Definitions
- Term
Resting Membrane Potential
- Meaning
The electrical potential difference across the plasma membrane of a neuron when it is not transmitting a nerve impulse, typically around -70mV.
- Term
Action Potential
- Meaning
A rapid, transient, all-or-none change in the membrane potential of a neuron or muscle cell, involving depolarization and repolarization.
- Term
Depolarization
- Meaning
A change in the membrane potential that makes the membrane potential less negative (closer to zero or positive). In nerve impulses, this is caused by the influx of Na+ ions.
- Term
Repolarization
- Meaning
A change in the membrane potential that makes the membrane potential more negative, returning it towards the resting potential. In nerve impulses, this is caused by the efflux of K+ ions.
- Term
Hyperpolarization
- Meaning
A change in the membrane potential that makes the membrane potential more negative than the resting potential.
- Term
Threshold Potential
- Meaning
The minimum level of membrane potential that must be reached to trigger an action potential. Typically around -55mV.
- Term
Refractory Period
- Meaning
A period following an action potential during which the neuron is unresponsive or less responsive to further stimulation. Includes absolute and relative refractory periods.
- Term
Saltatory Conduction
- Meaning
The propagation of action potentials along myelinated axons, where the impulse jumps from one Node of Ranvier to the next, significantly increasing conduction speed.
Learning objectives
Explain the ionic basis of resting membrane potential.
Describe the sequence of events during an action potential (depolarization, repolarization, hyperpolarization).
Identify the roles of voltage-gated Na+ and K+ channels.
Understand the concept of threshold potential and refractory periods.
Explain the mechanism of action potential propagation along the axon.
Differentiate between continuous and saltatory conduction.
Prerequisites
Cell membrane structure and function
Ion channels (passive and active)
Membrane potential (resting and action)
Sodium-Potassium pump
Common mistakes
Confusing depolarization and repolarization phases.
Forgetting the role of voltage-gated channels.
Misunderstanding the ionic basis of potential changes.
Not differentiating between continuous and saltatory conduction.
Keywords
Action Potential
Nerve Impulse
Depolarization
Repolarization
Resting Potential
Threshold Potential
Voltage-gated Channels
Sodium-Potassium Pump
Refractory Period
Saltatory Conduction
Nodes of Ranvier
Myelin Sheath
Practice preview
Which of the following is the correct sequence of events during the generation and conduction of a nerve impulse?…
medium
The rapid influx of which ion into the neuron causes depolarization during an action potential?…
easy
What event primarily causes the repolarization phase of an action potential?…
easy