synaptic transmission

Question 1

what is a neurotransmitter?

Answer 1

• the chemical that diffuses across the synapse to the next neuron in the chain
• Each has its own specific molecular structure that fits perfectly into a postsynaptic receptor site (like a lock and key)

Question 2

synaptic transmission

Answer 2

• process by which one neuron communicates with another
• Information passed down the axon of the neuron as an electrical impulse known as action potential.
• Once the action potential reaches the end of the axon it needs to be transferred to another neuron or tissue.
• It must cross over the synaptic gap between the presynaptic neuron and post-synaptic neuron.
• At the end of the neuron (in the axon terminal) are the synaptic vesicles, which contain chemical messengers, known as neurotransmitters.
• When the electrical impulse (action potential) reaches these synaptic vesicles, they release their contents of neurotransmitters.
• Neurotransmitters then carry the signal across the synaptic gap.
• They bind to receptor sites on the post-synaptic cell, thereby completing the process of synaptic transmission.

Question 3

what is excitation?

Answer 3

increasing the post-synaptic neuron’s positive charge and the likelihood of the message being passed on
- serotonin

Question 4

what is inhibition?

Answer 4

increasing the post-synaptic neuron’s negative charge and decreasing the likelihood of the message being passed on
- adrenaline

Question 5

define summation

Answer 5

• Summation is the combined effect of excitatory and inhibitory influences
  (EPSPs and IPSPs) determining whether the post-synaptic neuron fires
• If net effect on post-synaptic neuron is inhibitory= neuron less likely to fire
• If net effect on post-synaptic neuron in excitatory= neuron more likely to fire

Question 6

summarised version of synaptic transmission

Answer 6

• Action potential (electrical impulse) reaches the end of the neuron called
  the pre-synaptic terminal
• Electrical impulse triggers the release of neurotransmitters from the
  synaptic vesicles like serotonin or GABA
• Neurotransmitters diffuse across the synaptic cleft
• Neurotransmitters bind to receptor sites on the post-synaptic neuron
• This results in excitatory or inhibitory effects on the post-synaptic
  neuron