Describe the events involved in the generation and propagation of an action potential.
Question
Describe the events involved in the generation and propagation of an action potential.
Solution
The generation and propagation of an action potential involves several key steps:
-
Resting Potential: In a resting neuron, the inside of the neuron is negatively charged relative to the outside. This is due to the distribution of ions across the neuron's membrane, including sodium (Na+) and potassium (K+) ions. The resting membrane potential is typically -70 mV.
-
Stimulus: A stimulus causes the cell membrane at that point to depolarize (become less negative). If the stimulus is strong enough and reaches the threshold potential (usually -55 mV), it triggers an action potential.
-
Depolarization: Once the threshold potential is reached, voltage-gated Na+ channels open. Na+ ions rush into the neuron due to the concentration gradient, making the inside of the neuron positively charged relative to the outside. This rapid change in charge is the depolarization phase of the action potential.
-
Repolarization: At the peak of the action potential (+40 mV), the Na+ channels close and voltage-gated K+ channels open. K+ ions rush out of the neuron, returning the charge inside the neuron to a negative value. This is the repolarization phase.
-
Hyperpolarization: Sometimes, the K+ channels stay open a bit too long, causing more K+ to leave the neuron than is necessary. This results in the neuron becoming more negative than the resting potential, a state known as hyperpolarization.
-
Return to Resting Potential: The neuron's sodium-potassium pump restores the original distribution of Na+ and K+ ions, returning the neuron to its resting potential and readying it for the next action potential.
-
Propagation of the Action Potential: The action potential propagates down the neuron's axon like a wave. The influx of Na+ ions during depolarization causes the next section of the neuron to reach threshold and depolarize. This continues all the way down the axon to the synaptic terminals, where it triggers the release of neurotransmitters into the synapse.
This entire process happens very quickly, in just a few milliseconds, and allows neurons to transmit information over long distances.
Similar Questions
Explain the action potential?
Complete the sentences describing the events that occur during an action potential.An action potential will not occur unless the membrane potential at the (the initial segment of the axon) reaches a level called .When threshold is reached, of the initial segment open briefly, allowing to diffuse into the cell.As these ions enter the cell, the cell membrane undergoes , with the membrane potential increasing to a peak of approximately +30mV.As the peak of the action potential is reached, the sodium channels close and the open, allowing these ions to diffuse out of the cell.As cations leave the cell, the membrane potential at that part of the membrane once again becomes negative. This phase of the action potential is called , because the resting membrane potential is being reestablished.The membrane potential actually dips lower than -70mV because the potassium channels do not close quickly enough. This phase is called .
00. Which phase(s) of the action potential accounts for thegeneration and propagation of impulses by the heart withoutexternal stimulation?CABAll
The sequence of events that converts action potentials in a muscle fibre to a contraction is known as
Receptor potential initiated by an adequate stimulus:- a- develops always at it full magnitudesb- undergoes temporal summation onlyc- undergoes spatial summation onlyd- could initiate an action potential
Upgrade your grade with Knowee
Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.