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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.
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
What region of the cell secretes neurotransmitters?
Neurotransmitters are typically synthesized and stored in the synaptic vesicles of the presynaptic terminal, which is located at the end of the neuron. When an action potential arrives, these vesicles release neurotransmitters into the synaptic cleft to communicate with the postsynaptic neuron.
What is occurring between the dendritic end and the axon hillock?
Communication is happening between the dendritic end and axon hillock in the form of synaptic inputs. Neurotransmitters released from the dendritic end bind to receptors on the dendrite, causing electrical signals to travel through the dendrite and reach the axon hillock, where they are integrated to determine if an action potential is generated.
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.
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.
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
What happens when the action potential reaches the end of the axon at the axon terminals How does one neuron communicate with another neuron and complete the circuit?
When the action potential reaches the axon terminals, it triggers the release of neurotransmitters from synaptic vesicles into the synaptic cleft. These neurotransmitters bind to receptors on the postsynaptic neuron's membrane, leading to the generation of a new action potential in that neuron if the signal is strong enough. This process allows for communication between neurons, effectively completing the circuit and transmitting signals throughout the nervous system.
What region of the cell secretes neurotransmitters?
Neurotransmitters are typically synthesized and stored in the synaptic vesicles of the presynaptic terminal, which is located at the end of the neuron. When an action potential arrives, these vesicles release neurotransmitters into the synaptic cleft to communicate with the postsynaptic neuron.
What is occurring between the dendritic end and the axon hillock?
Communication is happening between the dendritic end and axon hillock in the form of synaptic inputs. Neurotransmitters released from the dendritic end bind to receptors on the dendrite, causing electrical signals to travel through the dendrite and reach the axon hillock, where they are integrated to determine if an action potential is generated.
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.
What is the basic structure of a neuron?
A neuron consists of three major parts: The dendrites, cell body, and axon. Most, though not all, axons are covered with myelin sheath which is made up of glial cells. The ends of axons are further divided into axon terminals. The axon terminal of one neuron and the dendrites of another is separated by the synaptic cleft.
How does a signal move through a neuron?
A signal moves through a neuron by traveling along the axon, which is a long, thin extension of the neuron. The signal is transmitted as an electrical impulse called an action potential. When the signal reaches the end of the axon, it triggers the release of neurotransmitters, which then carry the signal to the next neuron.
What causes a neuron to release neurotransmitters?
When an action potential reaches the end of a neuron's axon, it triggers the release of neurotransmitters from vesicles in the presynaptic terminal into the synaptic cleft. This process is mediated by the influx of calcium ions that enter the neuron during an action potential, causing the vesicles to fuse with the cell membrane and release their contents.
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.
What electrical impulse travels outward from the cell body along what?
Typically, the electrical signal that travels from the dendrites across the cell body travels by cable conduction properties (like cable TV). Once the signal reaches the axon hillock, which is the spot where the axon branches off the cell body, the electrical signal starts traveling by action potentials (and maybe some cable conduction). The signal travels to the terminal end of the axon where it initiates a calcium influx, which in turn initiates a release of neurotransmitter to act on the next, post-synaptic neuron. The axon is the long process (arm) that extends from the first cell body to the next neuron.
