Biopsychology : Synaptic Transmission Flashcards
What is Synaptic Transmission?
The process through which neurones communicate with each other through an exchange of chemical messengers called neurotransmitters.
Why does the functioning of a nervous system require synaptic transmission?
> Within a single neuron, information is transmitted via the nerve impulse (an electrical signal that travels down the length of an axon).
However, a nerve impulse annotate be directly transmitted to an adjoining neuron due the the fact that neurons do not directly touch. Small gaps called synapses exist between adjacent neurons, and these prevent the nerve impulse ‘jumping’ across from the presynaptic neuron to the postsynaptic neuron,
Therefore, communication between neurons relies on the exchange of neurotransmitters across the synapse.
Outline the process of synaptic transmission.
> In synaptic transmission, one neurone , called the presynaptic neuron,sends a signal (through the release of neurotransmitters ) , to another neuron (called the post synaptic neuron) which receives thus signal.
Synaptic transmission starts when a nerve impulse (electrical signal), reaches the axon terminal (end of axon) of the presynaptic neuron.
This triggers the release of neurotransmitters from the presynaptic neurons synaptic vesicles. There are storage sacs for neurotransmitters.
The neurotransmitters diffuse across the synapse.
The neurotransmitters bind with receptor sites located on the dendrites of the postsynaptic neuron. Neurotransmitters only bind with specific receptors. They do this through the lock and key theory.
The effect of the neurotransmitter on the postsynaptic neuron will vary depending on the type of neurotransmitter and the type of receptor site it binds with.
One effect of the binding of the neurotransmitter with the receptor site is excitation. This increases the probability of an action potential occurring in the postsynaptic neuron. When an action potential occurs, the inside of the postsynaptic neuron becomes positively charged, causing the nerve impulse to move down the axon.
Alternatively, the binding of a neurotransmitter with a receptor site might cause inhibition. This lowers the probability of an action potential occurring (meaning the nerve Impulse is less likely to travel down the postsynaptic neurons axon)
Synaptic transmission can be terminated by a process called reputake, in which neurotransmitters are taken back up into the synaptic vesicles of the neurotransmitter in the synapse, meaning neurotransmitters will be less likely to bind with and interact with the receptors on the postsynaptic neuron.
