Biopsychology: Synaptic Transmission Flashcards
What Is The Synaptic Transmission?
- The process by which neighbouring neurons communicate with each other by sending chemical messages across the synaptic cleft that separates them.
What Are Neurotransmitters?
- Brain chemicals released from synaptic vesicles that relay signals across the synapse from one neuron to another.
- Divides into those that have inhibitory or an excitatory function.
- Each has its own specific molecular structure that fits perfectly into a post-synaptic receptor site.
What Is Excitation?
- When a neurotransmitter e.g adrenaline, increases the positive charge of the post-synaptic neuron.
- Increases the likelihood that the neuron will fire and pass on the electrical impulse.
What Is Inhibition?
- When a neurotransmitter, e.g serotonin, makes change of the postsynaptic neuron more negative.
- Decreases the likelihood that the neuron will fire and pass on the electrical signal.
What Is The Synapse?
- The junction between two neurons.
- Includes the presynaptic neuron, the synaptic cleft and the postsynaptic receptor rite.
What Is The Synaptic Cleft?
- The space between pre-synaptic and post-synaptic neuron.
What Is Synaptic Vesicle?
- Small sacs on the end of a presynaptic neuron that contain neurotransmitters that will be released into a synapse.
What Is the Presynaptic Neuron?
- The transmitting neuron, before the synaptic cleft.
What Is The Postsynaptic Neuron?
- The neuron that is receiving the information at the synapse.
What Is The Postsynaptic Receptor Site?
- A receptor on the post-synaptic neuron.
- A neurotransmitter locks into a specific receptor on the post-synaptic neuron and this triggers an electrical impulse in the post synaptic neuron.
The Process Of Synaptic Transmission.
1) Electrical impulse travels down a pre-synaptic neuron along the axon and to the terminal buttons of that neuron.
2) Once at the terminal branch it stimulates the synaptic vesicles (contain neurotransmitter which are chemicals).
3) Neurotransmitters are released from the synaptic vesicles and travel across the synapse. Electrical impulse changes to chemical impulse.
4) Neurotransmitter cross the synapse to get to the dendrites of the post-synaptic neuron.
5) There are receptors (lock) on the dendrites of the post-synaptic neuron.
6) If the neurotransmitter (key) are the correct shape they fit into the receptor.
7) Connection between the neurotransmitter and the receptor can cause an electrical impulse to be created in the dendrites of the post-synaptic neuron. However depends on whether it depends on if neurotransmitter is excitatory or inhibitory.
8) If neurotransmitter is excitatory it is more likely that an electrical impulse will travel down the post-synaptic neuron and the process can begin all over again.
9) The neurotransmitter however does not always fit into the receptors. If this is the case there will be no electrical impulse created in the second neuron.
Excitation, Inhibition And Summation.
- Excitation - increases the likelihood of neuron firing.
- Inhibition - decrease the likelihood of a neuron firing.
- Whether or not post-synaptic neuron fires is decided by summation, which is the excitatory and inhibitory influences are summed up.
- If the net effect on the postsynaptic neuron is inhibitory - it is less likely to fire.
- If the net effect on the postsynaptic neuron is excitatory - it is more likely to fire.
Synaptic Transmission And Drugs.
- Drugs can have one of two impacts on synaptic transmissions:
Either increase the amount of neurotransmitter by blocking the re-uptake channels.
Or decrease the amount of neurotransmitter by blocking the receptors. - SSRIs in OCD block the re-uptake channels so serotonin remains in the synapse and can continue to bind with more receptors - too little serotonin is thought to cause OCD.
- Antipsychotics drugs in schizophrenia block the receptors to prevent dopamine binding as it is thought too much dopamine causes schizophrenia.
