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A.P. propagation consists of the movement of the action potential along the axon, axon terminals and dendrites. A.P. propagation is non-decremental meaning that the amplitude of the A.P. remains constant throughout the propagation. Action potentials are also follow the principle of all-or-none fashion. Meaning if there is not enough summation(adding of EPSPs and mEPPs) to bring the stimulus to threshold, then no AP will be elicited
An action potential is initiated at the axon hillock when the membrane potential reaches a threshold. This triggers the opening of voltage-gated sodium channels, allowing sodium ions to enter the axon and depolarize the membrane. This depolarization causes adjacent sodium channels to open, propagating the action potential down the axon by a process called saltatory conduction.
Hi, i can answer this up to my own A-level knowledge of Biology.
There are two types of neurone, myelinated or unmyelinated.
Firstly i will discuss the transmission of an action potential across a myelinated neurone.
Firstly a stimulus causes an influx of Na+ ions into the axon, this causes more sodium voltage-gated channels to open and so more Na+ ions move down the electrochemical gradient, this causes the axon to depolarise. This depolarisation may cross the threshold value for that neurone and hence induce an action potential. In myelinated neurones there are gaps in the electrical insulating layer of the myelin sheath, these are called nodes of ranvier. Localised currents arise at these nodes and nerve impules (action potentials) effectively 'jump' from node to node, this is called saltatory conduction.
In unmyelinated neurones, the opening of sodium voltage-gated ion channels will open, this causes an adjacent section of the neurone to become depolarised as a localised circuit is created, this process is repeated across the whole length of the neurone, travelling in one direction. This is due to the refractory period, this is where the sodium ion channels are closed breifly as it's repolarised by K+ ions, therefore as they are closed the action potential cannot move backwards, but forwards into a section of the neurone that is at resting potential.
I hope this is ok :)
A nerve impulse is an electrical signal that travels along an axon. There is an electrical difference between the inside of the axon and its surroundings, like a tiny battery. When the nerve is activated, there is a sudden change in the voltage across the wall of the axon, caused by the movement of ions in and out of the neuron. This triggers a wave of electrical activity that passes from the cell body along the length of the axon to the synapse.
The speed of nerve impulses varies enormously in different types of neuron. The fastest travel at about 250 mph, faster than a Formula 1 racing car. For the impulse to travel quickly, the axon needs to be thick and well insulated with myelin.
This uses a lot of space and energy, however, and is found only in neurons that need to transfer information urgently.
For example, if you burn your fingers it is important that your brain gets the message to withdraw your hand very quickly.
an action potential (also known as a nerve impulse or spike) is a pulse-like wave of voltage that travels along several types of cell membranes.
An influx of sodium ions from the current action potential depolarizes the adjacent area
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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.
What enters the axon during action potential?
Sodium ions enter the axon during action potential. This influx of sodium ions depolarizes the axon membrane, leading to the propagation of the action potential along the axon.
Where does the action potential occur on a neuron?
The action potential occurs at the axon hillock, which is the initial segment of the axon where the cell body transitions into the axon. This is where the threshold potential is reached and an all-or-nothing electrical signal is generated and propagated down the axon.
How fast does an action potential travel down a myelinated nerve?
An action potential can travel up to 100 times faster down a myelinated nerve compared to an unmyelinated nerve. This is due to the saltatory conduction process, where the action potential jumps between the nodes of Ranvier on the myelinated axon, rather than traveling continuously along the entire length of the nerve cell.
Where is action potential specifically found?
Action potentials are found in the axons of neurons, where they are responsible for transmitting electrical signals over long distances. The action potential is generated at the axon hillock and then propagated down the axon to communicate with other neurons or muscles.
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.
Are action potential and local potential reversible?
Action potentials are irreversible once they are initiated, as they are actively propagated along the axon. Local potentials are reversible and can either lead to action potential generation or diminish without propagating.
What enters the axon during action potential?
Sodium ions enter the axon during action potential. This influx of sodium ions depolarizes the axon membrane, leading to the propagation of the action potential along the axon.
Where does the action potential occur on a neuron?
The action potential occurs at the axon hillock, which is the initial segment of the axon where the cell body transitions into the axon. This is where the threshold potential is reached and an all-or-nothing electrical signal is generated and propagated down the axon.
How fast does an action potential travel down a myelinated nerve?
An action potential can travel up to 100 times faster down a myelinated nerve compared to an unmyelinated nerve. This is due to the saltatory conduction process, where the action potential jumps between the nodes of Ranvier on the myelinated axon, rather than traveling continuously along the entire length of the nerve cell.
What happens when you stimulate an axon in the middle?
When an axon is stimulated in the middle, an action potential is generated and travels in both directions along the axon. This is known as bidirectional conduction. The action potential is propagated away from the site of stimulation towards both the axon terminal and the cell body.
How far would an action potential propagated in an unmyelinated axon?
The impulse will go to the terminal end of the axon. Other wise the very purpose of the innervation will be defeated.
Where is action potential specifically found?
Action potentials are found in the axons of neurons, where they are responsible for transmitting electrical signals over long distances. The action potential is generated at the axon hillock and then propagated down the axon to communicate with other neurons or muscles.
Which part of the neuron can propagate an action potential?
The axon is the part of the neuron that can propagate an action potential. This process relies on the opening and closing of ion channels along the axon membrane to allow the action potential to travel from the cell body to the axon terminals.
What is the sequence of events along an axon?
The sequence of events along an axon involves the generation of an action potential at the axon hillock, propagation of the action potential down the axon via depolarization and repolarization of the membrane, and neurotransmitter release at the axon terminals to communicate with other neurons or target cells.
When an action potential is initiated on a nerve cell membrane it radiates and is propagated in all directions from the point of initial stimulation?
Correct. The action potential is initiated at a specific point on the cell membrane called the axon hillock, and it then travels down the axon in one direction. Once initiated, it spreads along the entire length of the axon and can be transmitted to other neurons or muscle cells.
A long structure leaving the cell body that action potential travel along is called the?
It is the Axon
