topic 8 - synapses Flashcards
1
Q
describenhow a signal passes from one neurone to another (4)
A
- (action potential arrives depolarising pre-synsptic membrane)
- Ca2+ ions diffuse into pre-synaptic neurone
- vesicles of neurotransmitter fuse with pre-synaptic membrane
- neurotransmitter diffuses across synapse
- neurotransmitter binds to receptor
- voltage gated NA+ ion chanels open alowing Na+ to moven into post-synaptic membrane causing depolarisation
- neurotransmitter broken down to preent further stimulation
2
Q
give an additional role of the synapse
A
- ensures one way transmission of impulse
- amplifacation of impulse via summation
- divergance of an impulse
3
Q
describe how MDMA coud prevent the transmission of nervous impulses in the brain
A
- prevents reuptake of serotonin
- by binding to post-synpatic receptors
- nerve pathways using serotonin are more likely to be stimulated
4
Q
how do low serotinin levels effect the transmission of impulses to the brain?
A
- less neurotransmitter
- threshold potential not achieved
5
Q
how does the use of MDMA lead to symptoms of depression ?
A
- results in depletion of serotonin
- post-synaptic membrane becomes less responsive to serotonin
- lack of serotonin linjked to depression
6
Q
describe the process that occurs at the synapse that leads to habituation (4)
A
- repeated stimulation leads to decreased sensitivity of PSM
- fewer Ca2+ move into neurone
- fewer vesicles fuse with membrane
- less neurotransmitter released
- depolarisation less likely to occur
7
Q
why does habituation occur?
A
animals dont waste energy reponding to a non-thretening signal
8
Q
through what process does neurotransmitter leave the pre synaptic neurone
A
exocytosis
9
Q
what happens after action potential has been generated and why
A
neurotransmitter is broken down to prevent further stimulation of neurone
10
Q
what is summation
A
- a single impulse may be insufficient to generate an action potential
- small amount of neurotransmitter released, few channels opened, threshold not reached
- effect of multiple impulses can be added together to overcome this
