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Sodium.A positive ion (cation) that enters the cell (influx) rapidly when the membrane threshold is reached and the voltage gated sodium channels open.This occurs during the rising phase of an action potential, i.e. membrane depolarization beyond the threshold for activation.
This occurs as K+ diffuses out of the cell.
Depolarization occurs when a stimulus opens sodium channels which allow more sodium to go into the membrane making it less negative and more positive (toward reaching threshold). An action potential can only occur once the membrane reaches threshold which means it has reached the level needed through depolarization. An action potential is a brief reversal in polarity of the membrane making the inside more positive and the outside more negative, the reverse occurs again once the membrane reaches resting potential.
Depolarization refers to the reversal of charges of neuron cell membrane, it occurs by moving in of 'Na' ions .
The action potential will not generate if the sodium channels are kept closed.This is because the sodium channels are responsible for the dramatic rising phase of membrane depolarization that occurs when the threshold of activation is reached. As a membrane potential gradually depolarizes (which can occur for a variety of reasons such as neurotransmitter stimulation, mechanical deformation of the membrane, etc), that membrane potential gradually comes closer to that threshold of activation. Once that threshold is reached, the voltage gated sodium channels open and allow for a dramatic influx of sodium ions into the cell. This results in a rapid depolarization which is seen as the rising phase of that upward spike noted in an action potential. Without the ability to open these sodium channels we may reach the threshold of activation, but the actual action potential will not occur.
Depolarization is due to the influx of Na+ which causes the cell's internal membrane to become more positive, leading to an action potential. Repolarization occurs when K+ leaves the cell causing the interior of the cell to become negative again.
Atrial depolarization occurs at the P wave. The atrial contraction occurs at the peak of the wave at the influx of calcium ions to prolong depolarization.
Sodium.A positive ion (cation) that enters the cell (influx) rapidly when the membrane threshold is reached and the voltage gated sodium channels open.This occurs during the rising phase of an action potential, i.e. membrane depolarization beyond the threshold for activation.
This occurs as K+ diffuses out of the cell.
Depolarization occurs when a stimulus opens sodium channels which allow more sodium to go into the membrane making it less negative and more positive (toward reaching threshold). An action potential can only occur once the membrane reaches threshold which means it has reached the level needed through depolarization. An action potential is a brief reversal in polarity of the membrane making the inside more positive and the outside more negative, the reverse occurs again once the membrane reaches resting potential.
Depolarization refers to the reversal of charges of neuron cell membrane, it occurs by moving in of 'Na' ions .
QRS
P wave
An excitatory postsynaptic potential, a type of graded potential, occurs because of the influx of Na+ through chemically gated channels in the receptive region, or postsynaptic membrane, of a neuron. Graded potentials are generated by chemically gated channels, whereas action potentials are produced by voltage-gated channels.
purkinje fibers
The action potential will not generate if the sodium channels are kept closed.This is because the sodium channels are responsible for the dramatic rising phase of membrane depolarization that occurs when the threshold of activation is reached. As a membrane potential gradually depolarizes (which can occur for a variety of reasons such as neurotransmitter stimulation, mechanical deformation of the membrane, etc), that membrane potential gradually comes closer to that threshold of activation. Once that threshold is reached, the voltage gated sodium channels open and allow for a dramatic influx of sodium ions into the cell. This results in a rapid depolarization which is seen as the rising phase of that upward spike noted in an action potential. Without the ability to open these sodium channels we may reach the threshold of activation, but the actual action potential will not occur.
depolarization