Synaptic Transmission Flashcards
Synaptic Transmission
When impulse reaches the end of the presynaptic nerve terminal, it triggers the release of neurotransmitters from synaptic vesicles which are like tiny sacks. Those neurotransmitters then diffuse across the synapse to the other side and are picked up by the postsynaptic receptor site. The neurotransmitter which is in a chemical form, will be translated back into an electrical signal and the message can be carried on along the next axon. Then the neurotransmitters are reabsorbed into the presynaptic neuron, or bind with receptors on the dendrite so they are ready for the next impulse that comes down the axon.
The neurons can only travel one way because the neurotransmitters are released from the presynaptic neuron and are received by the postsynaptic neuron. Thus, because the synaptic vesicles are at one place and the receptors at the other, it cannot travel the opposite way and has to travel one way.
Exhibition and Inhibition:
If a neuron is in the excitatory effect, that means there are too many positive charges and therefore it increases the likelihood of that neuron being fired, for example, this effect is brought by a neurotransmitter called adrenaline. However, the opposite of this is inhibitory effect where there are too many negative charges and therefore decreasing the chances of the neuron firing, this effect can be brought by the neurotransmitter serotonin. For example, in patients who have OCD have too many positive neurons and therefore their mind is constantly active, however, when they use drugs like SSRI to increase the level of serotonin, it is done to block the neurons from firing, thus allowing the brain to deactivate and relax. How frequently and if the neuron will fire is decided by summation which combines effects of excitatory and inhibitory signals.
