Most neurotransmitters are removed by being taken up by the presynaptic or postsynaptic neurones however acetylcholine is the prime exeption to this as is actually destroyed in the synaptic cleft by the enzyme acetylcholinesterase. The reason this must happen is that otherwise the neurotransmitter would be left in the cleft where it would continue to evoke a response in the postsynaptic cell for longer than it should. For this reason reuptake and catabolic enzymes are often the targets of drugs gieven to treat neurological disorders. Another possible problem is wastage, if the neurotransmitter is left in the cleft it may difuse away and be wasted giving the presynaptic neurone more work to do creating more.
The transport mechanism for a neurotransmitter across the synaptic cleft is called exocytosis. During exocytosis, neurotransmitter-filled vesicles fuse with the presynaptic membrane, releasing the neurotransmitter into the synaptic cleft where it can then bind to receptors on the postsynaptic membrane.
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.
Acetylcholine is a neurotransmitter that does not go through the reuptake process. Instead, it is broken down by an enzyme called acetylcholinesterase in the synaptic cleft.
Acetylcholinesterase is always present in the synaptic cleft of a neuromuscular junction. It is responsible for breaking down the neurotransmitter acetylcholine, allowing for the termination of the signal transmission between the neuron and the muscle cell.
Calcium (Ca2+) channels open on the synaptic end bulb in response to depolarization (from the action potential), inducing exocytosis of synaptosomes containing neurotransmitter, resulting in neurotransmitter being released into the synaptic cleft...further propagating the signal to the next neuron or set of neurons.
The transport mechanism for a neurotransmitter across the synaptic cleft is called exocytosis. During exocytosis, neurotransmitter-filled vesicles fuse with the presynaptic membrane, releasing the neurotransmitter into the synaptic cleft where it can then bind to receptors on the postsynaptic membrane.
Ca2+
Calcium ions enter the presynaptic neuron resulting in the release of neurotransmitter from the per-synaptic membrane. The neurotransmitter diffuses across the synaptic cleft, fusing with the receptors of the post-synaptic membrane. This changes the sodium channels to open and sodium ions will to flow into the post-synaptic neuron, depolarizing the post-synaptic membrane. This initiates an action potential. After the post-synaptic neuron has been affected, the neurotransmitter is removed by a type of enzyme called cholinesterase. The inactivated neurotransmitter then returns to the pre-synaptic neuron.
Neurotransmitters are released from the nerve terminals by a specialized exocytosis process, synaptic vesicles. These are small nearly uniform capsules that join with the cell membrane to expel their contents. Release is both quantal (set amount) and mediated by calcium.
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.
After a neurotransmitter travels through the synaptic cleft, it binds to receptors on the receiving neuron, which can either excite or inhibit the receiving neuron's activity. This process helps transmit signals between neurons in the brain and nervous system.
Synaptic vesicles in the axon terminals of neurons contain acetylcholine. Acetylcholine is a neurotransmitter that is released from these vesicles into the synaptic cleft to transmit signals to target cells or other neurons.
Calcium ions trigger the release of neurotransmitter at the presynaptic membrane. When an action potential reaches the presynaptic terminal, it causes voltage-gated calcium channels to open, allowing calcium ions to enter the cell. The influx of calcium ions triggers the fusion of synaptic vesicles with the presynaptic membrane, leading to the release of neurotransmitter into the synaptic cleft.
Synaptic terminals at the axon terminals of neurons would contain an abundance of vesicles containing neurotransmitters. These vesicles release neurotransmitters into the synaptic cleft to facilitate communication between neurons.
Short answer: Neurotransmitters Long answer: amino acids, monoamines, peptides
Acetylcholine is a neurotransmitter that does not go through the reuptake process. Instead, it is broken down by an enzyme called acetylcholinesterase in the synaptic cleft.
Acetylcholinesterase is always present in the synaptic cleft of a neuromuscular junction. It is responsible for breaking down the neurotransmitter acetylcholine, allowing for the termination of the signal transmission between the neuron and the muscle cell.