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17 Cards in this Set
- Front
- Back
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How are "messages" transmitted across neurons? |
Transmission of a message is through a synapse. This is a chemical process that requires neurotransmitters, which send information between the neurons, producing post synaptic potentials (PSP) |
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What is a synapse? |
The junction between the two neurons (terminal buttons & membrane)
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What is a synaptic cleft? |
The gap between the pre-synaptic membrane and the post-synaptic membrane
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Describe the stages involved in synaptic transmission? |
1. Transmitter is synthesised and then stored in vesicles 2. An action potential invades the pre-synaptic terminal 3. Depolarisation of pre-synaptic terminal causing the opening of voltage-dependent Ca2+ channels 4. Influx of Ca2+ through channels. 5. Ca2+ causes vesicles to fuse with pre-synaptic membrane. 6. Transmitter is released into synaptic cleft via exocytosis 7. Transmitter binds to a receptor molecule on the post-synaptic membrane 8. Opening or closing of post-synaptic channels 9. Postsynpatic currect causes excitation/inhibitory post synaptic portential that changes the exctiability of the postsynaptic cell 10. Removal of neurotransmitter by glial uptake or enzymatic degredation 11. Retrieval of vesicular membrane from plasma membrane |
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How do neurotransmitters bind? |
Neurotransmitters binds to ion channels on post-synaptic membrane, similar to lock and key model. Post synaptic potential depends on which ion channel (lock) is opened. |
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What type of post-synaptic potentials are there? |
EPSP - Excitatory Post-synaptic Potential IPSP - Inhibitory Post-synaptic Potential |
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What is a Ionotropic Receptor? |
It contains a binding site. Channels can be opened directly through these receptors. It is a fast response therefore good for vision and audio. |
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What is a metabotropic receptor? |
It contains a binding site It initiates a chain reaction that eventually opens ion channels. (G protein - produces enzyme - channels open) This is a slow process and therefore good for things we want to last such as taste, smell and pain. |
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How is the transmitter terminated? |
Enzyme Deactivation - transmitter broken down by an enzyme i.e. acetyl-cholinesterase breaks down Ach into choline and acetic acid. Reuptake - transmitter is taken back up by the pre-synaptic terminal |
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What does excitatory and inhibitory mean? |
refers to the increase in likelihood that a neuron will fire refers to the decrease in likelihood that a neuron will fire |
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Define integration |
This is the summation of PSPs in control of neuron firing
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What is the most abundant excitatory Neurotransmitter? |
In the CNS, it is glutamate, which is useful for learning and memory |
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What is the most abundant inhibitory neurotransmitter? |
In the CNS, it is GABA, which reduces the chance of neuronal firing.
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What is the neurotransmitter than is predominant in motor neurons? |
Acetyl-choline, found in CNS and PNS, it is specifically at neuromuscular junctions. |
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What is Ach's antagonist? |
Curare, which is a poison that prevents muscle contraction because it blocks the action of Ach |
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What is Ach's agonist? |
Muscatine is a poison that imitates the action of Ach. |
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What are monoamines? |
These are produced by neurons in the brain. G-protein coupled. They can be excitatory or inhibitory depending on the receptor subtype. e.g. Dopamine is useful for motor control and reward Serotonin is useful for regulation of mood, eating, sleep, arousal, and pain. |
