lecture 29 - Synaptic transmission Flashcards Preview

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Flashcards in lecture 29 - Synaptic transmission Deck (40):
1

glutamate transporter

removes glutamate to presynaptic terminals and astrocytes. Other transporters take it to be stored in synaptic vesicles

2

what are the 2 classes of neurotransmitters?

- small molecule neurotransmitters ('classical')
- neuropeptides ('neuromodulators')

3

substance P and endorphins

neuropeptides

4

synapse found in retina

electrical synapse

5

what does the increase of permeability to Cl-, due to IPSPs, cause ?

decreased cell membrane resistance. They make the current induced by EPSPs less efficient in bringing postsynaptic membrane to threshold.

6

metabotropic

indirectly gated glutamate receptors

7

how are most amino acids inactivated?

re-uptake

8

factors affecting synaptic action:

(a) type of neurotransmitter/neuroregulator
(b) type of neurotansmitter receptor expressed in post-synaptic membrane/ multiple receptor subtypes
(c) number of neurotransmitter receptors in the postsynaptic membrane - synaptic plasticity

9

Direct gating of ion channels (characteristics and features)

- transmitter binds directly to the ion channel complex and the pore opens
- very fast onset
- short-lived

10

neuromuscular junction =

chemical synaptic transmission between the axon terminals of motoneurons and the end-plates of muscle fibres

11

features of classical, small molecule neurotransmitters

fast action, acting directly

12

how small are the postsynaptic potentials?

around 0.1mV

13

AMPA, Kainate

directly gated glutamate receptors

14

too much glutamate release (or insufficient re-uptake) will lead to...

excitotoxicity: too much glutamate leads to excessive depolarisation of neurons. The long-term opening of NMDA receptors leads to excessive Ca2+ entering = damage to neurons

15

EPSPs and IPSPs work together TRUE/FALSE?

FALSE they work independently

16

axodentritic synapse

where the axon of one neuron communicates with the dentrite of another via chemical synapses

17

indirect gating of ion channels (characteristics and features)

- transmitter binds to G-protein coupled receptor or metabotropic receptors
-activates biochemical pathway, eventually opening pore
- slower onset
- longer-lasting

18

where would you find Pyramidal cells and what do they look like?

cerebral cortex of the brain. Pyramid shape

19

NPY

a neuropeptide

20

2 forms of synapses

1. chemical synapse
2. electrical synapse

21

IPSPs + EPSPs

cancel out

22

spatial summation

synapse activation occurs at the same time at many different synapses and the EPSPs add together

23

small molecule neurotransmitters include:

- Amino acids (glutamate, GABA, glycine)
- Acetylcholine (ACh)
- Amines (serotonin, dopamine, noradrenaline)
- others include ATP and Nitric oxide

24

inhibitory synapses cause a ________ of the post-synaptic membrane. The neurotransmitters involved are mainly ______ and ________ . Their ionic mechanism is the opening of the ion channels for __ and __ .

inhibitory synapses cause a _hyperpolarisation_ of the post-synaptic membrane. The neurotransmitters involved are mainly _GABA_ and _glycine_ . Their ionic mechanism is the opening of the ion channels for _K+_ and _Cl-_ .

25

through which type of cell junction are electrical synapses transmitted?

gap junction

26

where would you find Purkinje cells?

in the cerebellum

27

what are the two main chemical synapses in the CNS?

1. excitatory synapses (EPSPs)
2. inhibitory synapses (IPSPs)

28

excitatory synapses cause a ________ of the post-synaptic membrane. The neurotransmitters involved are mainly ________ _____ and ________ . Their ionic mechanism is the transient opening of the ion channels for __ and __ and sometimes __.

excitatory synapses cause a _depolarisation_ of the post-synaptic membrane. The neurotransmitters involved are mainly _glutamic_ _acid_(glutamate)_ and _Acetylcholine_(ACH)_ . Their ionic mechanism is the transient opening of the ion channels for _K+_ and _Na+_ and sometimes _Ca2+_.

29

features of neuropeptides

- Large molecules
- indirectly act on postsynatptic membrane
- slow and more dififfuse action

30

3 mechanisms of neurotransmitter inactivation

1. diffusion - away from the synaptic cleft
2. enzymatic degradation - e.g. ACH degraded by acetylcholinesterase
3. Re-uptake - neurotransmitter transporters take them away

31

_______ ________ arrives at the _________ terminal. The voltage-gated ___ channels open and there is a rapid influx of ___. _______ containing neurotransmitter move to the _________ membrane and fuse. The neurotransmitter ______ across the ______ ____ and binds to the ___________ receptors. Synaptic channels open. Postsynaptic _______ _________ is created.

_action_ _potential_ arrives at the _presynaptic_ terminal. The voltage-gated _Ca2+_ channels open and there is a rapid influx of _Ca2+_. _Vesicles_ containing neurotransmitter move to the _presynaptic_ membrane and fuse. The neurotransmitter _diffuses_ across the _synaptic_ _cleft_ and binds to the _postsynaptic_ receptors. Synaptic channels open. Postsynaptic _action_ _potential_ is created.

32

NMDA

a directly gated glutamate receptor

33

temporal summation

the higher the frequency of the synapse activation, from 1 synapse, the EPSPs can sum to reach threshold

34

end-plate potential due to ?

EPSP - therefore, increased permeability of (non-selective) ion channels to Na+ and K+ in the postsynaptic membrane

35

_______ synapse are used almost entirely in the brain

chemical

36

synaptic plasticity =

- process of weakening or strengthening synaptic transmission.
- Important in learning and memory.
- LTP (long-term potentiation) or LTD (long-term depression)

37

synaptic delay =

time between arrival of AP at presynaptic knob to AP regeneration in the postsynaptic knob. Aproximately = 0.5ms

38

3 key features of chemical synapses

1. specificity - specific neurotransmitters have specific effects
2. complexity - type, time, strength, etc.
3. plasticity - changes in synaptic structure and function

39

is end-plate potential supra- or sub- threshold

ALWAYS suprathreshold and ALWAYS triggers an AP

40

each neuron receives only 1 synapse TRUE/ FALSE

FALSE. they receive around 10,000