neurotransmitters

Question 1

properties of synaptic transmission

Answer 1

rapid timescale (2ms), diversity, adaptability, plasticity, learning and memroy

Question 2

3 stages of synpatic transmission pathway

Answer 2

transmitter released from 1st cell → synaptic activation of 2nd cell → signal integration and signal conduction by 2nd cell

Question 3

pathway of action potential in neurone

Answer 3

dendrites on spines → soma → axon → nerve endings/terminals

Question 4

what happens at dendrites

Answer 4

information reception

Question 5

what happens in the soma

Answer 5

integration of signals

Question 6

what happens in the axon

Answer 6

rapid transfer of action potential

Question 7

what happens at nerve terminals

Answer 7

synapse onto next body using neurotransmitter release

Question 8

main components of synapse

Answer 8

presynaptic nerve ending, synaptic cleft, postsynaptic region (dendrite/soma)

Question 9

how large is the synaptic cleft

Answer 9

20-100nm

Question 10

synaptic pathway process

Answer 10

action potential reaches presynaptic terminal → causes depolarisation → Na+ influx → K+ outflux → Ca2+ voltage-gated channels open → Ca2+ influx → synaptic vesicles containing neurotransmitters to fuse with membrane → neurotransmitters released by exocytosis → diffuse across synaptic cleft → bind to receptors on postsynaptic region → cause depolarisation → new action potential generated → neurotransmitters removed by transporter into cytosol → Na+/K+ balance restored by Na+/K+ ATPase pump

Question 11

why are there lots of mitochondria in the presynaptic terminal

Answer 11

lots of energy required to produce and release neurotransmitters

Question 12

is the synapse symmetrical or asymmetrical

Answer 12

asymmetrical

Question 13

properties of neurotransmitters

Answer 13

enormous diversity in variety of transmitters and receptors, mediate or slow effects, vary in abundance

Question 14

what makes up neurotransmitters

Answer 14

amino acids, amines, neuropeptides

Question 15

examples of amino acid neurotransmitters

Answer 15

glutamate, GABA, glycine

Question 16

properties of glutamate

Answer 16

most important and potent

Question 17

what is GABA

Answer 17

major inhibitory transmitter in CNS

Question 18

examples of amine neurotransmitters

Answer 18

noradrenaline, dopamine

Question 19

example of neuropeptide neurotransmitters

Answer 19

opioid peptides

Question 20

essential components of synaptic transmission

Answer 20

restricted to specialised asymmetric synapse, fast, Ca2+ influx essential, synaptic vesicles as source of neurotransmitter

Question 21

how does rapid release occur

Answer 21

synaptic vesicles filled with neurotransmitter and docked in synaptic zone “primed” → Ca2+ influx activates Ca2+ sensor in protein complex → interaction between synaptic vesicle and synaptic membrane proteins allow rapid response → exocytosis → neurotransmitter endocytosis → restart

Question 22

what do neurotoxins such as tetanus target

Answer 22

vesicular proteins

Question 23

components required for neurotransmitter release

Answer 23

transmitter containing vesicles to be docked on presynaptic membrane, protein complex formation between vesicle, membrane and cytoplasmic proteins (enable docking and rapid response), ATP and vesicle recycling

Question 24

receptors on postsynaptic membrane

Answer 24

ion channel and G-protein coupled

Question 25

relative speed and function of ion channel receptors

Answer 25

fast; mediate all fast excitatory and inhibitory transmission

Question 26

relative speed and function of G-protein coupled receptors

Answer 26

slow; activate effector: enzyme (e.g. adenyl cyclase) or channels (e.g. Ca2+)

Question 27

ion channel receptor in CNS

Answer 27

GABA

Question 28

ion channel receptor in NMJ (neuromuscular junction)

Answer 28

acetylcholine

Question 29

G-protein coupled receptor in CNS and PNS

Answer 29

acetylchonline, dopamine, noradrenaline, 5HT, neuropeptides

Question 30

properties of ion channel-linked receptors

Answer 30

rapid activation, diversity and rapid information flow, multiple subunit combinations for distinct functional properties

Question 31

GLUR

Answer 31

excitation (Na+ influx - depolarise membrane)

Question 32

GABAR

Answer 32

inhibitory (Cl- influx - hyperpolarise membrane)

Question 33

where is GLUR usually found

Answer 33

dendrites

Question 34

where is GABAR ususally found

Answer 34

soma so acts downstream of GLUR

Question 35

excitatory receptor (e.g. GLUR)

Answer 35

depolarises membrane

Question 36

inhibitory receptor (e.g. GABAR)

Answer 36

hyperpolarises membrane

Question 37

glutamate receptors

Answer 37

AMPA and NMDA

Question 38

AMPA receptor

Answer 38

Na+ influx; only acts on cell which has already been depolarised; majority of fast excitatory synapses

Question 39

NMDA receptor

Answer 39

Na+ and Ca2+ influx; Ca2+ modifies recepor, activates protein synthesis which modifies synapse formation; slow component of excitatory transmission; serve as coincidence detectors which underlie learning mechanisms

Question 40

excitatory synapse mediated by glutamate and inhibition

Answer 40

mediated by depolarising membrane; EAAT (transporter) takes glutamate into glial cell; conversion of glutamate to glutamine by glutamine synthetase

Question 41

what does abnormal cell firing associated with excess glutamate in synapse lead to

Answer 41

epileptic seizures

Question 42

epilepsy characterisation

Answer 42

recurrent seizures due to abnormal neuronal excitability

Question 43

GABA structure vs glutamate structure

Answer 43

GABA is glutamate without COOH group; catalysed by glutamic acid decarboxylase

Question 44

inhibitory synapse mediated by GABA and inhibition

Answer 44

mediated by hyperpolarising membrane; GAT (transporter) takes GABA into glial cell; conversion of GABA to succinate semialdehyde by GABA-T

Question 45

treating epilepsy

Answer 45

drugs dampen down excitatory activity and target pentameric organisation of GABA, enhancing enhance transmission and influx of Cl- (e.g. increases frequency of Cl- channel opening)