Neurotransmitters

Question 1

Name the parts of a neurone

Answer 1

Spins, Dendrites, Soma, Axon, Synaptic terminal

Question 2

What is the gap between neurones at a synapse?

Answer 2

20 - 100 nm

Question 3

List the 3 stages of synaptic transmission.

Answer 3

1. Biosynthesis, packaging and release of neurotransmitters
2. Receptor action
3. Inactivation

Question 4

What are the 2 most important neurotransmitters in the brain?

Answer 4

Glutamate - excitatory

GABA - inhibitory

Question 5

Outline the sequence of events in neurotransmitter release.

Answer 5

Membrane depolarisation
Ca2+ channels open
Ca2+ influx
Vesicle fusion
Vesicle exocytosis
Transmitter release
Endocytosis of empty vesicle

Question 6

What enables vesicle fusion and exocytosis?

Answer 6

Special vesicular proteins

Question 7

How does tetanus toxin act?

Answer 7

Breakdown of cholinergic transmission and therefore paralysis

Question 8

What does botulinum toxin do?

Answer 8

Causes flaccid paralysis

Question 9

How does alpha latrotoxin work?

Answer 9

Causes uncontrolled influx of Ca2+ and therefore depletion of neurotransmitter.

Question 10

How does entry of Ca2+ at the presynaptic membrane cause an effect?

Answer 10

Vesicular fusion and exocytosis of neurotransmitters from the plasma membrane

Question 11

Do ion channel receptors create a fast or slow response?

Answer 11

Fast

Question 12

Do G-protein coupled receptors create a fast or slow response?

Answer 12

Slow

Question 13

What is the effector of a G-protein coupled receptor?

Answer 13

Enzymes - adenyl cyclase

Channels - Ca2+

Question 14

Neurotransmitters for ion channel receptors (CNS)?

Answer 14

Glutamate

GABA

Question 15

Neurotransmitters for ion channel receptors (NMJ)?

Answer 15

ACh at nicotinic receptors

Question 16

Neurotransmitters for G-protein coupled receptors (CNS and PNS)?

Answer 16

ACh at muscarinic receptors
Dopamine
Noradrenaline
Serotonin
Neuropeptides

Question 17

How does an inhibitory neurotransmitter receptor work?

Answer 17

Cl- influx, membrane potential becomes more negative (hyper polarisation)

Question 18

How does an excitatory neurotransmitter receptor work?

Answer 18

Na+ influx, membrane depolarisation

Question 19

What are the two types of glutamate receptor?

Answer 19

AMPA - fast

NMDA - slow

Question 20

What abnormality at synapses is associated with seizures?

Answer 20

Excess glutamate

Question 21

What are the stages of an excitatory CNS synapse?

Answer 21

1. Glutamate synthesised from glucose via TCA cycle & transamination
2. Glutamate reversibly binds post-synaptic receptors (linked to ion channels)
3. Rapid uptake of glutamate by excitatory amino acid transporters (EAATs)
4. Glutamate enzymatically modified by glutamine synthetase to glutamine in glial cell

Question 22

What are the stages of an inhibitory CNS synapse?

Answer 22

1. GABA formed by decarboxylation of Glutamate by glutamic acid decarboxylase (GAD)
2. GABA reversibly binds post-synaptic receptors (linked to ion channels)
3. Rapid uptake of glutamate by GABA transporters (GATs)
4. GABA enzymatically modified by GABA-transaminase to succinate semialdehyde in glial cell

Question 23

How many subunits make up a GABA receptor?

Answer 23

5