Neurotransmitters Flashcards

1
Q

Where does integration of the signals coming down the dendrites occur?

A

In the soma

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2
Q

What is the width of a synaptic cleft?

A

20-100 nm

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3
Q

Describe the process of synaptic transmission.

A

The vesicles dock on the pre-synaptic membrane and await a signal before the contents of the vesicles are expelled into the synaptic cleft.

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4
Q

What are the three classes of neurotransmitter?

A

Amino acids
Amines
Neuropeptides

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5
Q

What allows the vesicles to dock stably?

A

Interaction between the vesicle membrane proteins and pre-synaptic membrane proteins.

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6
Q

What triggers the vesicle exocytosis?

A

There is a high concentration of calcium channels at the area where the vesicle docks. An influx of calcium causes vesicle exocytosis.

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7
Q

State three toxins that target vesicle proteins and the effects that they have.

A

Tetanus - causes spastic paralysis (zinc dependent endopeptidase)
Botulinum - causes flacid paralysis
Alpha-latrotoxin - prevents recycling of the vesicles and hence releases the transmitter to total depletion

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8
Q

What are the two types of receptor and what is the most important difference in their properties?

A

Ion Channel Receptor - FAST

G-protein linked receptor – SLOW

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9
Q

What is the effect of glutamate on the post-synaptic membrane?

A

Glutamate is excitatory - causes influx of Na+

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10
Q

What is the effect of GABA on the post-synaptic membrane?

A

GABA is inhibitory - causes influx of Cl-

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11
Q

What are the two main types of glutamate receptor? State some properties.

A

AMPA - rapid acting - responsible for the majority of fast excitatory synapses
NMDA - slower acting (despite still being excitatory and fast) - requires two conditions for activation = depolarisation of membrane + glutamate binding
NMDA lets in Na+ and Ca2+

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12
Q

Where is glutamate formed?

A

Glutamate is a product of intermediary metabolism (e.g. glycolysis and TCA cycle)

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13
Q

Which transporter takes glutamate up into glial cells on the pre-synaptic membrane?

A

Excitatory Amino Acid Transporter 2 (EAAT 2)

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14
Q

How is glutamate inactivated in the glial cells?

A

Glutamate is converted to glutamine by GLUTAMINE SYNTHETASE

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15
Q

What causes epilepsy?

A

Increased release of glutamate causing hyperexcitability

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16
Q

Describe the structure of GABA and state how it is produced.

A

GABA has the same structure as Glutamate but with the carboxyl group removed. So GABA is produced from glutamate by the action of GLUTAMIC ACID DECARBOXYLASE (GAD).

17
Q

What transporter takes GABA up into the glial cells?

A

GABA Transporter (GAT)

18
Q

Describe the inactivation of GABA in the glial cells.

A

GABA is converted to SUCCINATE SEMIALDEHYDE by GABA Transaminase

19
Q

Describe how the GABA receptor can be manipulated to create treatments for epilepsy.

A

There are binding sites on the pentameric GABA receptor for benzodiazepines, steroids, barbiturates etc. so these sites can be manipulated to facilitate the activity of GABA and produce antiepileptic drugs.