Synaptic Transmission

Question 1

Synaptic transmission

Answer 1

Is the term referring to the process by which neighbouring neurons communicate with each other by sending chemical messages across the gap (synapse) that separates them.

Question 2

Chemical transmission - synapses

Answer 2

Neurons communicate with each other within groups called neural networks.
Each neuron is separated from the next by a tiny gap called the synapse.
Signals within the neurons are transmitted electrically, however signals between neurons are transmitted chemically across the synapse.
When the electrical impulse reaches the end of the neuron (the pre-synaptic terminal) it triggers the release of neurotransmitter from the tiny sacs called synaptic vesicles.

Question 3

Neurotransmitters

Answer 3

Neurotransmitters are chemicals that diffuse across the synapse to the next neuron in the chain.
Several types of neurotransmitter have been identified in the brain.
Each neurotransmitter has it’s own specific molecular structure that fits perfectly into the post-synaptic receptor site.
Neurotransmitters also have specific functions. For example acetylcholine is found at each point where a motor neuron meets a muscle, and upon it’s release it will cause muscles to contract.

Question 4

Neurotransmitter process after transfer

Answer 4

Once the neurotransmitter crosses the gap, it is taken up by the post-synaptic receptor site (the dendrites of the next neuron).
Here the chemical message is converted back into an electrical impulse and the process of transmission begins again in this other neuron.

Question 5

Excitation

Answer 5

Excitation refers to when a neurotransmitter increases the positive charge of the post-synaptic neuron.
This increases the likelihood that the neuron will fire and pass on the impulse.

Question 6

Inhibition

Answer 6

Inhibition refers to when a neurotransmitter increases the negative charge of the post-synaptic neuron.
This decreases the likelihood,that the neuron will fire and pass on the electrical impulse.

Question 7

Neurotransmitters with excitation and inhibition

Answer 7

Neurotransmitters have either an excitatory or an inhibitory effect on the neighbouring neuron.
The neurotransmitter serotonin causes inhibition in the receiving neuron, resulting in the neuron becoming more negatively charged and less likely to fire.
In contrast adrenaline causes excitation of post-synaptic neuron by increasing it’s positive charge and making it more likely to fire.