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What most directly causes synaptic vesicles to release acetylcholine into the synaptic cleft?
Wiki User
∙ 11y ago
calcium entering the axon terminal
Wiki User
∙ 11y ago
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Synaptic vesicles in the axon terminal of a motor neuron contain what neurotransmitter?
Synaptic vesicles store neurotransmitters to be released into the synapses. In the case of most motoneurons, this neurotransmitter is acetylcholine (ACh). The neurons that interface with the sympathetic nervous system, also technically motoneurons, release norepinephrine.
What are the tiny sacs found within the terminal button which release chemicals into the synapse?
The tiny sacs in the synaptic knob are known as synaptic vessels. The synaptic vessels release chemicals into the bloodstream with each synapse.
Which area would contain an abundance of vesicles containing neurotransmitter?
Neurotransmitters are stored in synaptic vesicles within axonal terminals for release into the synaptic cleft.
What is the ion needed to initiate the release of acetylcholine into the synaptic cleft called?
calcium - Ca2+
What ion triggers the release of a neurotransmitter at the presynaptic membrane?
Calcium triggers synaptic vesicles to discharge the neurotransmitter into the synaptic cleft.
Synaptic vesicles in the axon terminal of a motor neuron contain what neurotransmitter?
Synaptic vesicles store neurotransmitters to be released into the synapses. In the case of most motoneurons, this neurotransmitter is acetylcholine (ACh). The neurons that interface with the sympathetic nervous system, also technically motoneurons, release norepinephrine.
What causes calcium ions to enter the synaptic bulb?
The nerve signal arrives at a synaptic knob and causes calcium channels to open. This allows the calcium ions to enter the synaptic knob. Calcium ions entry into the synaptic knob triggers exocytosis of synaptic vesicles, which release acetylcholine into the synaptic cleft.
What are the tiny sacs found within the terminal button which release chemicals into the synapse?
The tiny sacs in the synaptic knob are known as synaptic vessels. The synaptic vessels release chemicals into the bloodstream with each synapse.
Which area would contain an abundance of vesicles containing neurotransmitter?
Neurotransmitters are stored in synaptic vesicles within axonal terminals for release into the synaptic cleft.
What is the ion needed to initiate the release of acetylcholine into the synaptic cleft called?
calcium - Ca2+
How does the nervous stimulus pass to the motor end plate?
An activated neuron will send an action potential from upper motor neurons to lower motor neurons to effector organs. It is able to propagate the action potential to the motor end plate by release of neurotransmitters, chiefly acetylcholine. On the terminal bouton the action potential opens voltage gated calcium channels. There is an influx of calcium in the pre-synaptic cell and it pushes the vesicles that contain acetylcholine. These vesicles will pass through the synaptic cleft and bind to cholinergic receptors on the post synaptic neuron. Each vesicle has a miniature end plate potential of 0.5mV. In a normal action potential, it will depolarize the post synaptic motor neuron from -85mV to approximately 0-15mV. So that's approximately 180 vesicles.* The influx of neurotransmitters (primarily acetylcholine) will depolarize the motor end plate and propagate the action potential. *Threshold of an action potential is approximately -55mV so technically the minimum required to continue an action potential is around 60 vesicles.
What ion triggers the release of a neurotransmitter at the presynaptic membrane?
Calcium triggers synaptic vesicles to discharge the neurotransmitter into the synaptic cleft.
What is the chemical transmitter released at the neuromuscular junction?
The neurotransmitter acetylcholine is released into the synaptic cleft to bind with receptors on muscle cells. Upon binding, the muscle cells contract.
How do Presynaptic neurons release neurotransmitters?
They don't, the neurotransmitters stay on either side of the synapse. Neurotransmitters are released when the synaptic vesicles fuse with the presynaptic neuron's membrane, so as to release them into the synaptic cleft.
How are neurotransmitters broken down in the synaptic cleft?
most neurotransmitters are not actually broken down, rather they are actively transported back into their pre release vesicles (this is called reuptake). Some neurotransmitters are broken down by a specific enzyme into non active parts i.e acetylcholine broken down by acetylcholinestarase
What causes the synaptic delay?
The cause of synaptic delay is attributed mainly to the time needed for the synaptic vesicles to release neurotransmitter into the synaptic cleft. While it can be considered a combination of binding to the presynaptic membrane (which is relatively a transient process) and subsequent exocytosis of the neurotransmitter, the main factor is release. Additionally, it does take a very short period of time for the neurotransmitter to diffuse across the synaptic cleft and bind to to its receptors on the post-synaptic membrane.
What do the bubbles of chemical crossing the synapse do?
Chemicals called neurotransmitters move across the synaptic gap by diffusion and carry a neural signal across to the receiving neuron. But the 'bubbles' (vesicles) which contained the neurotransmitter chemicals do NOT themselves cross the synaptic gap, they just release the neurotransmitters into the synaptic gap. (The neurotransmitters move across the synapse, the vesicles do not.)The vesicles release their contents of neurotransmitters into the synaptic gap by a process called exocytosis, in which the neural impulse which reaches the terminal button of the presynaptic neuron causes voltage-gated calcium ion pores to open, allowing an influx of calcium ions, which leads to the fusing of the vesicles to the cell membrane, which amounts to the vesicles 'turning themselves inside out' as the membrane of the vesicle merges with the cell membrane, which expels the neurotransmitters into the synaptic gap.The neurotransmitters flow across the synapse to bind with the postsynaptic neuron, potentially triggering neuron excitation (firing) or inhibition (preventing firing).
