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Information in the form of bioelectricity is propagated by changes in the…
Information in the form of bioelectricity is propagated by changes in the membrane potential of neurons
Membrane potential is the difference between the electrical potential on the inside and outside of a cell and is dictated by different electrical characteristics
Equilibrium potential is the membrane potential where chemical and electrical gradients result in no net movement of ions
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Steady state is similar to equilibrium in that there is no net movement, but a steady state may require input of energy to maintain the state
The resting potential of neurons requires contribution from the Na+/K+ pump, which uses ATP
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Reversal potential (V_Rev): membrane potential where the net current through an open ligand- gated ion channel (or receptor) would be zero.
For example, the reversal potential at the NMJ is ~ -10 mV because the conductance of sodium equals the conductance of potassium through the nAChR.
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Ions that traverse the membrane include potassium, sodium, chloride, and calcium
The general pathway of information is receptor potential to local potential to action potential to synapse to synaptic potential
A Receptor Potential is elicited due to the stimulation of the stretch receptors in the quadriceps muscle
Local potential: a small, stimulus caused, change in the resting membrane potential of a neuron.
Threshold potential: the level needed for a membrane potential to initiate an action potential. Typically between -30 and -45 mV.
Subthreshold potential: a synaptic potential that does not cause depolarization above threshold above action potential potential.
Suprathreshold potential: a synaptic potential (or summation of potentials) that does elicit an action potential.
Action potential: a wave of depolarization that propagates from the trigger zone and through the axon to the axon terminal and active zone
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Speed of action potential is affected by electrical properties of the nerve fiber: membrane resistance, membrane capacitance, and axial resistance
The more myelinated an axon is, the faster an action potential can travel because the membrane resistance is increased and the membrane capacitance is decreased.
The further distance an action potential can depolarize the axon without needing to evoke another action potential, the faster it propagates because firing up an action potential takes time due to the opening mechanism of channels.
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An action potential consists of the rising phase, overshoot, falling phase and the undershoot.
The rising phase is due to the regenerative depolarization of the membrane potential due to the increase in Na+ conductance.
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The receptor potential is graded potential. IT may differ in size, shape, or duration, depending on the stimulus and response properties of the responding neuron
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