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When the action potential reaches the end of an axon, it causes special chemical messages called neurotransmitters to be released across the space between the neurons (the synapse).
Wiki User
∙ 13y ago
Wiki User
∙ 11y agoIt stimulates small vesicles filled with neurotransmitters to move to and fuse with the cell membrane, which allows the neurotransmitters to be released into the synapse.
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What effect does an action potential have on a vesicle?
It causes the vesicles (which are in the axon terminal) to move to the cell membrane at the end of the axon terminal, where they merge with the cell membrane, releasing their load of neurotransmitters into the synaptic cleft (gap), where they quickly diffuse to receptors in the post-synapticneuron's dendrites, initiating a graded potential which moves down the dendrites, along the soma,to the axon hillock where it can cause an action potential in that secondneuron.
Describe an action potential?
Firstly, a stimulus causes an influx of sodium ions into the axon. This causes further sodium voltage-gated ion channels to open, causing more sodium ions to move into the axon, down an electrochemical gradient, this depolarises the axon, if the influx of sodium ions reaches the threshold value of the axon then an action potential is produced. The sodium-voltage gated channels close when the potential of the axon reaches +40 mv. Potassium ion channels open, allowing K+ ions out of the axon and into surrounding tissue fluid. The electrical gradient is reversed and more potassium ions leave the axon. This is repolarisation. As more potassium ion channels are open compared to at resting potential, hyperpolarisation occurs. This is where the axon is more negative then usual. The sodium-potassium pump actively transports 3 Na+ ions out of the axon and 2K+ ions into the axon, with the use of ATP; allowing the resting potential to be reastablished.
When the what reaches the end of the axon the neurotransmitter is released?
When the _____________reaches the ends of the axon the neurotransmitter is released and it diffuses to the muscle cell membrane to combine with receptors there?Sarcolemma
Parts of a neuron include?
dendrites -Apex
Does a neuron become more negative during a nerve impulse?
No. The inside of the neuron becomes more positively charged. The resting potential is -70 millivolts. So, the outside of the neuron starts off being more positively-charged, and the inside is more negatively-charged. As sodium ions (which are cations - positively-charged ions) move into the neuron (via sodium ion channels), this depolarizes the neuron (induces a "signal"). If this net signal is above a certain threshold, it will trigger an action potential, whereby channels will open in the axon, just ahead of the action potential itself, which allows more cations to flow into the axon, increasing the positive charge inside the axon, and further triggering the opening of cation channels downstream. Note: As the action potential (positively-charged region inside an axon) propagates down the axon, sodium channels open behind it to pump sodium ions back outside the axon, restoring the inner negative charge of that region, so that it can return to the resting potential. Therefore, once the action potential is formed inside the axon, and is moving downstream, sodium pumps open behind it so that the signal is dampened in an already-activated region, thereby restoring the resting potential. This prevents retriggering a secondary action potential (which would result in amplification of the end signal). On the other hand, when an inhibitory neurotransmitter binds with the neuron, or else a chloride ion channel (chloride ions are anionic - negatively-charged) opens, chloride ions enter the neuron, which drives the membrane potential further into the negative, thereby reducing the likelihood of action potential (signal) generation.
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.
What effect does an action potential have on a vesicle?
It causes the vesicles (which are in the axon terminal) to move to the cell membrane at the end of the axon terminal, where they merge with the cell membrane, releasing their load of neurotransmitters into the synaptic cleft (gap), where they quickly diffuse to receptors in the post-synapticneuron's dendrites, initiating a graded potential which moves down the dendrites, along the soma,to the axon hillock where it can cause an action potential in that secondneuron.
Describe an action potential?
Firstly, a stimulus causes an influx of sodium ions into the axon. This causes further sodium voltage-gated ion channels to open, causing more sodium ions to move into the axon, down an electrochemical gradient, this depolarises the axon, if the influx of sodium ions reaches the threshold value of the axon then an action potential is produced. The sodium-voltage gated channels close when the potential of the axon reaches +40 mv. Potassium ion channels open, allowing K+ ions out of the axon and into surrounding tissue fluid. The electrical gradient is reversed and more potassium ions leave the axon. This is repolarisation. As more potassium ion channels are open compared to at resting potential, hyperpolarisation occurs. This is where the axon is more negative then usual. The sodium-potassium pump actively transports 3 Na+ ions out of the axon and 2K+ ions into the axon, with the use of ATP; allowing the resting potential to be reastablished.
When the what reaches the end of the axon the neurotransmitter is released?
When the _____________reaches the ends of the axon the neurotransmitter is released and it diffuses to the muscle cell membrane to combine with receptors there?Sarcolemma
Motor end plate is?
Motor end plate of a cell is the dendritic portion that have cholinergic receptors to receive neurotransmitters in order to propagate an action potential.
Parts of a neuron include?
dendrites -Apex
Does a neuron become more negative during a nerve impulse?
No. The inside of the neuron becomes more positively charged. The resting potential is -70 millivolts. So, the outside of the neuron starts off being more positively-charged, and the inside is more negatively-charged. As sodium ions (which are cations - positively-charged ions) move into the neuron (via sodium ion channels), this depolarizes the neuron (induces a "signal"). If this net signal is above a certain threshold, it will trigger an action potential, whereby channels will open in the axon, just ahead of the action potential itself, which allows more cations to flow into the axon, increasing the positive charge inside the axon, and further triggering the opening of cation channels downstream. Note: As the action potential (positively-charged region inside an axon) propagates down the axon, sodium channels open behind it to pump sodium ions back outside the axon, restoring the inner negative charge of that region, so that it can return to the resting potential. Therefore, once the action potential is formed inside the axon, and is moving downstream, sodium pumps open behind it so that the signal is dampened in an already-activated region, thereby restoring the resting potential. This prevents retriggering a secondary action potential (which would result in amplification of the end signal). On the other hand, when an inhibitory neurotransmitter binds with the neuron, or else a chloride ion channel (chloride ions are anionic - negatively-charged) opens, chloride ions enter the neuron, which drives the membrane potential further into the negative, thereby reducing the likelihood of action potential (signal) generation.
A synaptic knob would be located on a?
A synaptic knob is a tiny bulge at the end of a terminal branch of a presynaptic neuron's axon!
What are the five parts of a neuron?
The four major parts to the neuron are the dendrites, soma, axon hillock and terminal boutons.The dendrites receive input from other neurons, and integrate this information into the cell. They may result in either temporal or spatial summation which may result in depolarization of the cell.The soma, or cell body of the axon contains all of the organelles of the cell - the nucleus, mitochondria, etc. and is important for maintenance of the neuron.The axon hillock is the area of the cell with the highest number of ion channels present in the membrane, and also is the area of the cell that demarcates the start of the axon. From here, upon summation of stimuli, an action potential can be generated by the massive influx of ions into the cell, resulting in the generation of the action potential which is propagated through the axon.At the terminal bouton, this is where the action potential triggers a response. Using the neuromuscular junction as an example, when the action potential reaches the end of the terminal bouton, Ca2+ influx is triggered at the endplate resulting in the release of neurotransmitters, in this case, Acetylcholine, which causes contraction in the muscle.
What is the result of sodium ions moving across the axons membrane during an action potential?
a neural impulse(electrical impulse) is released and it travels down the axon of a neuron to the axon terminals. At the axon terminal there are sacs called synaptic vesicles which contain chemicals called neurotransmitters. When the neural impulse reaches the terminal it causes the sacs to move closer to the membrane of the axon terminal and release the neurotransmitters inside. Then neurotransmitters travel across the synaptic gap and stimulate the dendrites of another neuron and the whole process starts again.
When an action potential reaches the end of a neuron it triggers the release of?
When an action potential reaches the end of a neuron, it triggers the release of neuotransmitters such as epinephrine (sympathetic) or achetylcholine (parasympathetic).
How does the end plate potential differ from a EPSP on a post synaptic cell?
End plate potential is the change in potential from neurotransmitters. It can be excitatory or inhibitory. If the action potential wants to continue, it will be excitatory and vice versa. It can be additive, if more action potentials are fired it will increase the end plate potential. An action potential is an all or none response. It will either proceed or it will not proceed depending on the terms of the threshold. It cannot be additive, because there is an absolute refractory period where no additional action potentials can be fired.
