5.1 Synapses Flashcards Preview

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Flashcards in 5.1 Synapses Deck (33):
1

what is a synapse?

the junction between two neurones

2

how does information pass across the synaptic cleft?

chemicals called NEUROTRANSMITTERS

3

what is the presynaptic neurone?

the neurone along which the impulse arrives

4

what is the synaptic knob and what does it contain?

swollen end of the presynaptic neurone containing many mitochondria and large amounts of ER to make neurotransmitters

5

what are synaptic vesicles? what do they do?

vesicles containing neurotransmitters
fuse with the membrane to release neurotransmitters

6

what is the synaptic cleft?

the gap separating the axon of one neurone from the dendrite of the next

7

what are receptor sites?

receptor molecules which the neurotransmitter binds to on the postsynaptic neurones membrane

8

what do synapses ensure about impulses?

they are UNIDIRECTIONAL

9

which two ways can an impulse be transmitted?

- to a number of neurones at multiple synapses resulting in a number of simultaneous responses
- a number of neurones can feed into the same synapse with a single postsynaptic neurone

10

1. neurones are not in direct contact, what separates them?

the synaptic cleft

11

2. when an action potential arrives at the end of a presynaptic neurone what does it cause to open?

calcium channels resulting in calcium flooding in to the axon

12

3. what does increased levels of calcium stimulate?

synaptic vesicles to move toward membrane of presynaptic neurone.

13

3. what neurotransmitter do the vesicles contain?

acetylcholine

14

4. vesicles fuse with the membrane and acetylcholine is released into the synaptic cleft by what process?

exocytosis

15

5. how does acetylcholine move across the synaptic cleft?

diffusion

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5. what does acetylcholine do when it reaches the post synaptic neurone and what does this result in?

binds to receptors on sodium ion channels, results in the channels opening allowing sodium to flood in

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6. what does the flooding in of sodium do to the postsynaptic membrane?

depolarizes it and if the threshold value is reached an action potential is generated

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7. what is acetylcholine broken down into?

ethanoic acid and choline

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7. what enzyme breaks down acetylcholine?

acetylcholinesterase

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7. where is acetylcholinesterase found?

in the synaptic cleft

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8. what do choline and ethanoic acid do?

diffuse back into the presynaptic neurone

22

8. when choline and ethanoic acid diffuse back into the presynaptic neurone what happens?

ATP from the mitochondria used to recombine them back to acetylcholine

23

which sort of synapses use the neurotransmitter acetylcholine?

cholinergic synapses

24

where are cholinergic synapses found?

in the CNS of invertebrates at neuromuscular junctions

25

why is the amount of neurotransmitter from a single impulse not enough to trigger an action potential in postsynaptic neurone?

threshold value not reached

26

what does a stimulatory drug do?

creates more action potentials resulting in enhanced response

27

what does an inhibitory drug do?

creates fewer action potentials resulting in reduced response

28

what sort of drug is alcohol? what does it do?

inhibitory
binds to GABA receptors

29

what does GABA do?

decreases activity of brain by preventing nervous transmission

30

what does Prozac block? what does this do?

the reuptake of serotonin
more action potentials generated increasing serotonin levels

31

what is Prozac used to treat?

depression

32

what is temporal stimulation?

action potentials from one neurone arrive in rapid succession

33

what is spatial stimulation?

several action potentials from different neurones arrive at post synaptic membrane at same time

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