PSYCHOBIOLOGY: synaptic transmission

Question 1

structures in the presynaptic neuron associated with the chemical synapse

Answer 1

• axon terminal with postsynaptic membrane
• vesicles filled with neurotransmitters
• Ca+ ion channels

Question 2

functions of the presynaptic neuron associated with the chemical synapse

Answer 2

• action potential arrives & Ca+ channels open
• Ca+ ions enter the axon terminal
• vesicles fuse with the presynaptic membrane
• neurotransmitters are released into the synaptic cleft

Question 3

describe the synaptic cleft

Answer 3

• between pre & postsynaptic neurons
• neurotransmitters diffuse across

Question 4

structures in the postsynaptic neuron associated with the chemical synapse

Answer 4

• postsynaptic membrane
• various ion channels

Question 5

functions of the postsynaptic neuron associated with the chemical synapse

Answer 5

• neurotransmitters bind with ion channels at receptor sites
• ion channels open & ions enter the postsynaptic neuron
• a postsynaptic potential is generated & neurotransmitters are released from the receptor site

Question 6

what are voltage gated ion channels?

Answer 6

channels which open in response to electricity - a membrane potential change

Question 7

give 3 examples of voltage gated ion channels

Answer 7

• K+ channels in axon hillock / axon
• Na+ channels in axon hillock / axon
• Ca+ channels in axon terminal membrane

Question 8

what are transmitter gated ion channels?

Answer 8

channels which open in response to neurotransmitters binding with the channel receptors

Question 9

what are ionotropic channels?

Answer 9

type of transmitter gated channel
- opens directly: receptor sits on channel & opens it

Question 10

what are metabotropic channels?

Answer 10

type of transmitter gated channel
- opens indirectly: receptor is away from channel so NT binds to a region which activates G protein, releasing second messengers which open the ion channel

Question 11

what type of ion channels are in the postsynaptic membrane?

Answer 11

transmitter gated

Question 12

describe excitatory neurotransmitters

Answer 12

positive ions enter & the membrane depolarises so action potential is more likely

Question 13

describe inhibitory neurotransmitters

Answer 13

negative ions enter & the membrane hyper polarises so action potential is less likely

Question 14

what is postsynaptic summation?

Answer 14

electrical changes in a postsynaptic neuron triggered by a single action potential insufficient to generate a new AP
- integrates several AP changes

Question 15

temporal summation

Answer 15

combines postsynaptic potentials occurring in rapid succession

Question 16

spatial summation

Answer 16

combines postsynaptic potentials from different synapses

Question 17

what is addendum?

Answer 17

neurotransmitter removal

Question 18

why must NTs be actively removed?

Answer 18

they do not change when they bind to a receptor so must be removed to stop influence on the postsynaptic cell

Question 19

degradation

Answer 19

special enzymes in synaptic cleft break down NTs - components are partly recycled to make new NTs

Question 20

reuptake

Answer 20

receptor molecules at presynaptic axon terminal take up NTs & return them to the presynaptic neuron