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What are the criteria for a substance in a neurotransmitter at a synapse?
Criteria required identifying a substance as a neurotransmitter 1- ) Synthesis of the substance: • It is synthesized in the neuron • Some substances are synthesized from the Tryptophan • Rate limiting step in its synthesis • Enzymes required in the synthesis of that substance are themselves synthesized in the cell body of neuron ,then distributed throughout the neuron • Mainly found in the cell body and nerve terminal • These enzymes are stored in the presynaptic terminal of neuron, inside the synaptic vesicles. 2- ) Storage of that substance: • The neutransmitter is stored inside the synaptic vesicle of nerve terminal 3- ) Release of the neurotransmitter: • It is released from the nerve terminal usually through Ca++ dependent process following the stimulation of the nerve fiber by action potential. • Fusion of the synaptic vesicle with the nerve membrane releasing neurotransmitter outside the nerve fiber into the synaptic cleft. 4- ) Exogenous analogue (drug) of the neurotransmitter: • If drug analogue of the neurotransmitter is injected exogenously, it should mimic the same mechanism of action as done by the endogenously released neurotransmitter.
What is presynaptic inhibition and how does it regulate neurotransmitter release in the nervous system?
Presynaptic inhibition is a process in which the release of neurotransmitters from a neuron is reduced by another neuron. This regulation occurs when the inhibitory neuron releases a neurotransmitter that decreases the excitability of the presynaptic neuron, leading to a decrease in neurotransmitter release. This mechanism helps to fine-tune communication between neurons and maintain balance in the nervous system.
How is the neurotransmitter acetylcholine inactivated at the parasympathetic terminal receptor site?
Acetylcholine is primarily inactivated at the parasympathetic terminal receptor site by the enzyme acetylcholinesterase. Acetylcholinesterase breaks down acetylcholine into choline and acetate, which are then taken back up by the presynaptic terminal for further use in neurotransmitter synthesis. This inactivation process allows for the rapid termination of acetylcholine signaling and helps maintain proper neurotransmitter balance in the synapse.
What is rueptake?
The process by which a presynaptic nerve cell takes neurotransmitter out of the synapse and recycles it to prevent too much signaling.
How Neurotransmitter molecules are removed from a synapse by?
Neurotransmitter molecules are removed from a synapse through a process called reuptake or enzymatic degradation. In reuptake, the neurotransmitter is taken back up into the presynaptic neuron. In enzymatic degradation, special enzymes break down the neurotransmitter molecules into inactive byproducts.
What is the process of a neurotransmitter being absorbed into the axon terminal?
When an action potential reaches the axon terminal, it triggers the opening of voltage-gated calcium channels. Calcium ions enter the axon terminal, leading to the fusion of neurotransmitter-containing vesicles with the synaptic membrane. The neurotransmitter is then released into the synaptic cleft where it can bind to receptors on the postsynaptic neuron.
What ion causes presynaptic vesicle to fuse to axon membrane?
The calcium ion is responsible for causing the presynaptic vesicle to fuse to the axon membrane in a process called exocytosis. When an action potential reaches the presynaptic terminal, calcium ions enter the terminal and trigger the fusion of the vesicle with the axon membrane, releasing neurotransmitters into the synaptic cleft.
What is the re absorption of excess neurotransmitter molecules?
Reabsorption of excess neurotransmitter molecules refers to the process where neurotransmitters are taken back up from the synaptic cleft into the presynaptic neuron by transporters known as reuptake pumps. This process helps regulate neurotransmitter levels, preventing overstimulation of the postsynaptic neuron. Dysfunction in this reabsorption process can lead to neurological disorders such as depression and anxiety.
What most directly causes synaptic vesicles to release acetylcholine into the synaptic cleft?
The entry of calcium ions into the presynaptic terminal triggers the fusion of synaptic vesicles containing acetylcholine with the cell membrane, leading to the release of acetylcholine into the synaptic cleft. This process is known as calcium-dependent exocytosis and is a key mechanism for neurotransmitter release at synapses.
when a dendrite pulls the neurotransmitter in the opposite directions its is called?
Reuptake. Reuptake is the process by which neurotransmitters are taken back up into the presynaptic neuron after being released into the synaptic cleft.
What happened to the neurotransmitter release when switched from the control extracellular fluid to the extracellular fluid with no calcium?
There is no neurotransmitter release from the axon terminal when there are no calcium ions in the extracellular solution. This is because the exocytosis of the synaptic vesicles is calcium dependent.
What ion enters the axon nerve terminal to cause exocytosis of the neurotransmitter is called?
The ion that enters the axon nerve terminal to trigger neurotransmitter release is calcium (Ca2+). When an action potential reaches the nerve terminal, voltage-gated calcium channels open, allowing calcium ions to flow into the cell and initiate the process of exocytosis of neurotransmitter-containing vesicles.
