Synaptic Transmission

Question 1

How does synaptic transmission begin?

Answer 1

• Once action potential is at the terminal button, it needs to be transferred to the next neuron.
• It must cross the presynaptic neuron and the postsynaptic neuron gap, known as the synapse.
• The physical gap is called the synaptic gap.

Question 2

Describe electric transmission (within neurons)

Answer 2

• Dendrites recieve info from other neurons
• This passes to the cell body and then goes to the axon, forming an electrical signal

Question 3

What is synaptic transmission?

Answer 3

The process by which nerve impulses pass across the synaptic gap

Question 4

What are neurotransmitters?

Answer 4

Chemical substances that play an important role in the workings of the nervous system by transmitting nerve impulses across a synapse

Question 5

What happens at the end of the axon in synaptic transmission? (1)

Answer 5

• At the end of the axon of the nerve cell are sacs called synaptic vesicles. These vesicles have chemical messengers that aid in the transfer of the impulses (neurotransmitters)
• As action potential reaches the synaptic vesicles, it causes them to release their contents through a process called exocytosis.

Question 6

What happens once the neurotransmitter is released? (2)

Answer 6

Released neurotransmitter diffuses across the synaptic gap, where it binds to specialised receptors of the cell that recognise it and are activated, the receptor molecules produce either excitatory or inhibitory effects on the postsynaptic neuron.

Question 7

Describe the effects of synaptic transmission

Answer 7

• Effects terminated at synapses through ‘re-uptake’.
• Neurotransmitter is taken up again by presynaptic neuron, where it’s stored and made available for later.
• The quicker the presynaptic neuron takes back the neurotransmitter from the synaptic gap means the shorter the effects on the postsynaptic neuron.

Question 8

Apply synaptic transmission to antidepressants

Answer 8

Some antidepressant drugs prolong the action of the neurotransmitter by inhibiting this re-uptake process, leaving the neurotransmitter in the synapse for longer

Question 9

How can neurotransmitters be ‘turned off’?

Answer 9

• Neurotransmitter can be ‘turned off’ after they’ve stimulated the postsynaptic neuron.
• Takes place through the action of enzymes produced by the body, which make the neurotransmitter ineffective