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Where do most local potentials happen?
Local potentials typically occur in the dendrites and cell body of a neuron. They involve small changes in membrane potential that do not reach the threshold for generating an action potential. These local changes in potential allow for signal integration and processing in the neuron.
Graded potentials will not be initiated by?
Graded potentials will not be initiated by hyperpolarization. Graded potentials are subthreshold changes in membrane potential that can depolarize or hyperpolarize a cell, but they are typically initiated by a stimulus, such as neurotransmitter binding or sensory input. Hyperpolarization alone may not be strong enough to reach the threshold for generating a graded potential.
What is a sub-threshold change in membrane potential within the cell body that decays as it travels away from its point of origin?
A sub-threshold change in membrane potential in the cell body, such as an excitatory post-synaptic potential (EPSP), does not reach the threshold for action potential initiation. As it travels along the dendrites and cell body, it decays and dissipates, failing to trigger an action potential. This phenomenon is crucial in the integration of signals by neurons.
Which membrane potential occurs because of the influx of Na plus through chemically gated channels in the receptive region of a neuron?
The membrane potential that occurs due to the influx of Na+ through chemically gated channels in the receptive region of a neuron is called the excitatory postsynaptic potential (EPSP). This influx of Na+ leads to depolarization of the neuron, bringing it closer to the threshold for generating an action potential. EPSPs can summate to trigger an action potential if they reach the threshold potential.
Triggering of the muscle action potential occurs after?
depolarization of the cell membrane reaches a threshold level. This threshold is usually around -55mV. Once threshold is reached, voltage-gated sodium channels open, allowing sodium ions to rapidly enter the cell and generate an action potential.
Which part of the neuron is capable of generating an action potiental?
The axon hillock is the part of the neuron that is capable of generating an action potential. It integrates incoming signals from the dendrites and, if the threshold is reached, triggers the action potential to be propagated down the axon.
How does a threshold prevent a neuron from generating too many action potential?
A threshold in a neuron represents the critical level of depolarization needed to trigger an action potential. When the membrane potential reaches this threshold, voltage-gated sodium channels open, allowing an influx of sodium ions that leads to rapid depolarization. If the membrane potential does not reach this threshold, the neuron will not fire, thus preventing excessive or spontaneous action potentials. This mechanism ensures that action potentials are generated only in response to sufficient stimuli, maintaining proper signaling in the nervous system.
A neuron fires only when its membrane reaches what?
A neuron fires when its membrane reaches a certain threshold potential. This threshold potential is typically around -55 to -65 millivolts. When the membrane potential reaches this level, an action potential is triggered and the neuron fires.
Where do most local potentials happen?
Local potentials typically occur in the dendrites and cell body of a neuron. They involve small changes in membrane potential that do not reach the threshold for generating an action potential. These local changes in potential allow for signal integration and processing in the neuron.
What is sub threshold Depolarization of nerves?
Sub threshold depolarisation of nerves, would be the influx of sodium (and maybe efflux of potassium depending) that doesn't cause enough depolarisation for an action potential to be fired. The summation of sub threshold depolarisations may cause an AP to be released. if they 'tip the balance' far enough. Hope this helps Edit: Above answer is vague. Sub threshold depolarizations do not occur as a result of efflux of potassium, which hyperpolarizes a neuron. They can be generated as EPSPs at the post synaptic membrane or result from persistant sodium channels, which do not completely inactivate (contributing to pacemaking activity). In both cases, gradual depolarization can lead to action potential generation.
Neuron receives a series of stimuli whose effect is excitatory but subthreshold?
Then it does nothing unless the stimuli arrive at the same time to be above the threshold. Or the stimuli may undergo temporal summation (with buildup of neurotransmitters in the synapse), where their effects add up over time to be above the threshold.
What stimulus below this intensity will result in no response in a neuron?
Any stimulus below the neuron's threshold potential will not result in a response, as it is not strong enough to generate an action potential. Neurons require a minimum level of stimulus intensity to reach the threshold potential and fire an action potential.
Membrane potential required to achieve threshold?
-55mV
What behavior is observed if the voltage across a neuronal membrane is set to -20 mV?
If the voltage across a neuronal membrane is set to -20 mV, this would be closer to the threshold potential for neuron firing, leading to an increased likelihood of the neuron generating an action potential. At this level, the neuron is closer to depolarization and may be more excitable compared to when the membrane potential is at resting potential.
How does threshold change during the relative refractory period?
During the relative refractory period, the threshold for excitation is increased compared to the resting threshold. This is because the membrane potential is closer to its resting state, making it more difficult to depolarize the cell and generate an action potential. It requires a stronger stimulus to overcome this increased threshold and trigger another action potential.
Minimum level of stimulation required to trigger a neural impulse?
The minimum level of stimulation required to trigger a neural impulse is known as the "threshold." This threshold is the minimum amount of neurotransmitter release or electrical stimulation needed to generate an action potential in a neuron. Below this threshold, the neuron will not fire an action potential.
When several neurons are stimulated equally which one will fire first?
The neuron with the lowest threshold potential will fire first when several neurons are stimulated equally. Threshold potential is the minimum level of depolarization needed to trigger an action potential in a neuron. Neurons with lower threshold potentials are more excitable and will fire before neurons with higher threshold potentials.
