Synaptic Transmission

Question 1

How can neuronal morphology be mapped?

Answer 1

using a golgi stain

Question 2

What is an electrical synapse?

Answer 2

a synapse with no gap between the pre and post-synaptic terminals, action potential travels directly

Question 3

What is a chemical synapse?

Answer 3

action potential travels by neurotransmitters being released from a presynaptic terminal and acting on postsynaptic receptors

Question 4

What is an axodendritic synapse?

Answer 4

an axon connecting to a dendrite (most common)

Question 5

What is an axosomatic synapse?

Answer 5

an axon connecting to a soma

Question 6

What is an axoaxonic synapse?

Answer 6

an axon connecting to another axon

Question 7

What are classical neurotransmitters?

Answer 7

amino acids; glutamate, GABA, glycine
monoamines; DA, NE, 5-HT
acetylcholine

Question 8

What are non-classical neurotransmitters?

Answer 8

neuropeptides
gases
lipids

Question 9

How are classical neurotransmitters synthesised?

Answer 9

dietary precursors cross the BBB where enzymes in the axon terminals synthesise them into neurotransmitters and pack them into vesicles

Question 10

How are non-classical neurotransmitters synthesised?

Answer 10

neuropeptide transmitters are synthesised in the cell body

Question 11

What are the 3 R’s of neurotransmitter storage?

Answer 11

readily releasable pool; docked to cell membrane, rapid release, rapid depletion
recycling pool; mobilised by moderate stimulation, fairly rapid release
reserve pool; mobilised by intense stimulation, slow release

Question 12

What factors determine neurotransmitter release?

Answer 12

rate of cell firing
probability of neurotransmitter release
presence of auto receptors on axon terminals

Question 13

What are the functions of auto receptors?

Answer 13

terminal; inhibit further neurotransmitter release

somatodendritic; slow the rate of cell firing

Question 14

What happens during receptor binding?

Answer 14

NT rapidly diffuse across narrow synaptic cleft
binding to any receptors in the vicinity
often significant spillover into nearby synapses

Question 15

What mechanisms are used during inactivation?

Answer 15

reuptake

enzyme degradation

Question 16

What is reuptake?

Answer 16

reuptake transporters suck NT back into the presynaptic terminal

Question 17

What is enzyme degradation?

Answer 17

processes such as metabolism excretion and cycling rapidly degrade the NT’s

Question 18

What percent of action potentials trigger NT release?

Answer 18

10-20%

Question 19

What is signal transduction?

Answer 19

transmitters bind to a receptor changing the conformation and elicit intracellular changes

Question 20

What is an ionotropic receptor?

Answer 20

a ligand-gated channel that opens to allow the flow of ions; receptor conformation is changed

Question 21

What are the effects of an ionotropic receptor?

Answer 21

fast and rapidly reversible

Question 22

What are the types of ionotropic receptor?

Answer 22

NDMA
AMPA
Kainate

Question 23

What are the features of NMDA receptors?

Answer 23

found on dendritic spines
slower neurotransmission
a magnesium block is removed when there is a high firing rate

Question 24

What are the features of AMPA receptors?

Answer 24

found on dendritic spines

most fast excitatory responses to glutamate are mediated by AMPA

Question 25

What are metabotropic receptors?

Answer 25

g-protein-coupled receptors single proteins with 7 transmembrane domains indirectly influence cellular activity through a cascade of events slower signalling than ionotropic

Question 26

By what mechanisms can g-proteins signal?

Answer 26

direct coupling to an ion channel which inhibits/stimulates the channel coupling to a second messenger (effector enzyme) system

Question 27

How do second messenger systems work?

Answer 27

second messengers activate protein kinases which activate other second messenger systems by phosphorylation

Question 28

What is a colour metric reaction?

Answer 28

antibodies can detect antigens, secondary antibodies can detect primary antibodies and produces a colour close to the initial protein

Question 29

What is a fluorescence reaction?

Answer 29

antibodies can be used to detect an antigen (proteins), secondary antibodies detect the primary antibody which have fluorophores which glow when light is shined on them

Question 30

What are gene regulatory pathways?

Answer 30

second messengers can alter gene transcription or regulation by activating transcription factors