Table of Contents
Are action potentials short or long?
Action potentials are the basic events the nerve cells use to transmit information from one place to another. The recordings in the figure above illustrate three very important features of nerve action potentials. First, the nerve action potential has a short duration (about 1 msec).
What causes a smaller action potential?
Voltage-gated sodium channels are responsible for the fast action potentials involved in nerve conduction. Slower action potentials in muscle cells and some types of neurons are generated by voltage-gated calcium channels.
Which type of action potential can travel short distance?
Graded potentials
Graded potentials don’t travel long distances along the neuron’s membrane, but rather, travel just a short distance and diminish as they spread, eventually disappearing.
What are the two types of action potential?
Action potential
| Definition | Sudden, fast, transitory and propagating change of the resting membrane potential |
|---|---|
| Phases | Depolarization Overshoot Repolarization |
| Refractoriness | Absolute – depolarization, 2/3 of repolarization Relative – last 1/3 of repolarization |
| Synapse | Presynaptic membrane Synaptic cleft Postsynaptic membrane |
Is action potential a stimulus?
The action potential is an explosion of electrical activity that is created by a depolarizing current. This means that some event (a stimulus) causes the resting potential to move toward 0 mV. Action potentials are caused when different ions cross the neuron membrane. A stimulus first causes sodium channels to open.
What happens if you increase extracellular sodium?
The increase in the Na+ influx leads to a further depolarization. A positive feedback cycle rapidly moves the membrane potential toward its peak value, which is close but not equal to the Na+ equilibrium potential. Two processes which contribute to repolarization at the peak of the action potential are then engaged.
Why does myelin decrease capacitance?
Myelin reduces membrane capacitance by increasing the thickness of the membrane (increase in separation of cations and anions) and by decreasing the amount of charge stored on both sides of the membrane.
What conducts the action potential?
Neurons conduct electrical impulses by using the Action Potential. Neurons, like all cells, maintain different concentrations of certain ions (charged atoms) across their cell membranes.
Why does action potential only move away from the cell body?
An efflux of potassium from the current action potential depolarizes the adjacent area. Why does the action potential only move away from the cell body? The flow of the sodium ions only goes in one direction—away from the cell body. The areas that have had the action potential are refractory to a new action potential.