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Semester 3 > Case 2 - introduction to neurotransmission > Flashcards

Case 2 - introduction to neurotransmission Flashcards

1
Q

what are neurones made up of

A
  • cell body
  • axon terminals
  • dendrites
  • axon
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2
Q

what is the cell body made up of

A

nucleus, stores DNA and rough ER which builds protein and mitochondria

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3
Q

what are the dendrite region

A

the input region; receives input from other neurones

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4
Q

what are the axon terminals

A

the output region; release of neurotransmitter

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5
Q

what is the axon region

A

main conduction unit. carries information in the form of electrical signal known as the action potential

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6
Q

what starts and initiates all transmission

A

the dendrites

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7
Q

what can electrical signals not transfer through

A

the synaptic gap

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8
Q

what two things can synaptic transmission be

A

electrical or chemical

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9
Q

what are the pre and post synaptic elements int he chemical synapse separated by

A

the synaptic cleft

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10
Q

what are majority of signals carried in

A

chemical format

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11
Q

what two clusters of cell bodies, dendrites and axons project to different parts of the brain

A

the substantial nigra and the ventral tegmental

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12
Q

when does an action potential occur

A

when a neurone sends information down an axon

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13
Q

how do neurones act as a signalling mechanism

A

by altering their resting membrane potential

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14
Q

what happens at the presynpatic terminal

A

the action potential opens Ca2+ channels and initiates neurotransmitter release

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15
Q

what does the myelin sheath do

A

speeds up conduction and are an insulator for the axon

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16
Q

what happens when you reach threshold

A

you get the opening of the sodium channels.

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17
Q

what gradients does sodium have

A

electrical and chemical

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18
Q

what is the benefit of sodium having two gradients

A

cause more sodium channels to open and therefore get a huge depolrisation and get a very fast influx of sodium ions

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19
Q

what happens once inside the cell is positive

A

the sodium channel closes and get repolarisation

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20
Q

what is repolarisation due to

A

potassium channels

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21
Q

how does potassium move

A

we know that there is more potassium ibnsde the cell, and at this point It is positive inside the cell swell. therefore potassium leaves the cell and this is repolarisation.

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22
Q

what is hyoerpolarisation due to

A

potassium channels being a little slower to close

23
Q

what is the neurotransmitter released into the synapse by

A

exocytosis

24
Q

where are neurotransmitters stored

A

the synaptic vesicle

25
Q

what is exocytosis

A

where the presynaptic vesicles bind to the presynaptic membrane, then the neurotransmitter is pushed out into the synaptic cleft

26
Q

why is there no excess excitation

A

enzymes break down the transmitter in the cleft

27
Q

what determines wether it is an excitatory or inhibitory signal

A

the receptor

28
Q

what is an ionotropic receptor

A

receptor that is part of ligand gated ion channel protein and activation results in ion conductance changes.

29
Q

what are inotropic receptors opened by

A

the transmitter to allow the passage of Na+ (excitatory) or K+/Cl- (inhibitory) and are involved in fast transmission - milli seconds

30
Q

what are examples of inotropic receptors

A

acetylcholine, glutamate and GABA

31
Q

what are metabotropic receptors

A

receptor protein in membrane that is coupled to effector mechanism via G proteins. in this signalling mechanism, agonist molecule combines with receptor proteins in the membrane

32
Q

what does this result in

A

conformational change causes activation of a membrane associated enzyme via G protein

33
Q

an example of a metabotropic receptor

A

dopamine receptor - they are a lot slower

34
Q

receptors summary

A
35
Q

what is the rate determining step in dopamine synthesis

A

tyrosine hydroxylase as it is normally saturated by substrate

36
Q

what is dopa decarboxylase

A

high activity and nonselective

37
Q

diagram showing synthesis of dopamine

A
38
Q

how is dopamine stored

A

in the synaptic vesicles in the axonal terminal

39
Q

where is dopamine released

A

into the synaptic cell upon the arrival of an action potential and influx of Ca2+

40
Q

what 2 postsynaptic receptors does dopamine bind to

A

D1 family: D1&D5 - excitatory
D2 family: D2,3,4 - inhibitory

41
Q

what enzymes metabolise dopamine

A

COMT and MAO

42
Q

what is the reuptake process

A

catecholamines have a highly specific active transport mechanism to remove the transmitter from the synapse into presynaptic terminal

43
Q

what is the dopamine transporter

A

DAT

44
Q

what pathway is drug overuse focused on

A

the mesolimbic pathway

45
Q

description of the mesolimbic pathway

A
  • ventral tegmental area in the midbrain to limbic regions associated with reward, motivation, affect and memory.
  • include ventral striatum (Nucleus accumbens), amygdala, hippocampus and medial prefrontal cortex
46
Q

which pathway does Parkinson’s affect

A

the nigrostriatal pathway

47
Q

what would you give to someone with Parkinsons

A

L-dopa because if you give L tyrosine it doesn’t matter how much you have because the tyrosine hydroxyls is the limiting factor as it is saturated.
or an agonist at D1 receptors

48
Q

what is the major excitatory neurotransmitter in the CNS

A

glutamate

49
Q

summary of dopamine pathways

A
50
Q

order of signalling pathway in brain

A
  1. spinal cord
  2. medulla
  3. thalamus
  4. cortex
51
Q

what are the 5 regions of the basal ganglia

A
  • caudate nucleus
  • putamen
  • globus pallidus
  • sub thalamic nucleus
  • substantia nigra
52
Q

the direct pathway

A
53
Q

what is the major inhibitory neurotransmitter

A

GABA

54
Q

where is acetylcholine released

A

at the neuromuscular junction

Semester 3 (94 decks)

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