6. BIOPSYCHOLOGY (THE PROCESS OF SYNAPTIC TRANSMISSION – INCLUDING REFERENCE TO NEUROTRANSMITTERS, EXCITATION, AND INHIBITION) Flashcards
What is synaptic transmission?
- Synaptic transmission is the process by which neighbouring neurons communicate by sending chemical messages across the synapse, the gap that separates them.
What is a neurotransmitter?
- A neurotransmitter is a brain chemical released from synaptic vesicles that relays signals across the synapse from one neuron to another.
- Neurotransmitters can be excitatory or inhibitory.
What are the two types of neurotransmitters?
- Excitatory neurotransmitters – They make the post-synaptic neuron more likely to fire.
- Inhibitory neurotransmitters – They make the post-synaptic neuron less likely to fire.
What is the process of synaptic transmission?
- An electrical impulse (action potential) travels down the axon of a neuron.
- The action potential reaches the axon terminal and triggers the release of neurotransmitters from synaptic vesicles.
- Neurotransmitters cross the synaptic gap and bind to receptors on the post-synaptic neuron.
- The binding of neurotransmitters produces excitatory or inhibitory effects on the post-synaptic cell.
What are excitatory neurotransmitters and what do they do?
- Excitatory neurotransmitters, such as noradrenaline, increase the positive charge of the post-synaptic neuron.
- This increases the likelihood that the neuron will fire and pass on the electrical impulse.
What are inhibitory neurotransmitters and what do they do?
- Inhibitory neurotransmitters, such as GABA, increase the negative charge of the post-synaptic neuron.
- This decreases the likelihood that the neuron will fire and transmit the electrical impulse.
What is summation in synaptic transmission?
- Summation is the net effect of the excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs) added together.
- It determines whether the post-synaptic neuron will fire an action potential or not.
What does the lock and key system in synaptic transmission refer to?
- The lock and key system refers to how neurotransmitters (the “key”) bind to specific receptors (the “lock”) on the post-synaptic neuron, opening ion channels and allowing ions to flow through the membrane.
What is the analogy used to explain excitation and inhibition in synaptic transmission?
- The analogy compares excitation to the accelerator pedal and inhibition to the brake pedal in a car:
o Excitation increases the likelihood of the neuron firing (like pressing the accelerator).
o Inhibition decreases the likelihood of the neuron firing (like pressing the brake).
What is the role of dopamine as an excitatory neurotransmitter?
- Dopamine is an excitatory neurotransmitter that increases the positive charge of the post-synaptic neuron, making it more likely to fire and transmit the electrical impulse.
How does serotonin function as an inhibitory neurotransmitter?
- Serotonin is an inhibitory neurotransmitter that increases the negative charge of the post-synaptic neuron, making it less likely to fire and pass on the electrical impulse.
What happens after neurotransmitters bind to receptors on the post-synaptic neuron?
- Once the neurotransmitters bind to receptors, they activate the post-synaptic neuron and either produce excitatory or inhibitory effects, which determine whether the neuron will fire.
What is the role of synaptic vesicles in synaptic transmission?
- Synaptic vesicles contain neurotransmitters and release them into the synapse when stimulated by an electrical impulse, enabling the transmission of signals between neurons.
What determines whether the post-synaptic neuron will fire?
- The balance between excitatory and inhibitory inputs at the receptor sites determines whether the post-synaptic neuron will reach the threshold to fire an action potential.
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