Chemical signalling

Question 1

What happens when action potentials reach terminal bouton?

Answer 1

Open Ca2+ channels

Question 2

What happens when Ca2+ channels open?

Answer 2

SNARE proteins activated; they cause docking of vesicles

Question 3

What happens when vesicles dock?

Answer 3

Proteins cause tension in vesicular membrane; active system!

Question 4

What ion (generally) does GABA affect?

Answer 4

Chloride

Comes into the cell and creates a negative charge

Question 5

What are other names for direct-gated receptors?

Answer 5

fast-acting, ionotropic

Question 6

What does a direct-gated receptor look like in terms of mechanism of action?

Answer 6

Neurotransmitter binds to transmembrane protein

Transmembrane protein opens, lets ions flow through

Question 7

Do ionotropic or metabotropic receptors have a larger amplitude?

Answer 7

Metabotropic

Ionotropic only let ions flow through where they’re active; metabotropic causes large changes in the cell through second messengers

Question 8

Which group of transmitters are generally associated with EPSPs/IPSPs (ionotropic)?

Answer 8

GABA, glutamate, acytylcholine

Question 9

What is the ‘quanta’ of a transmitter?

Answer 9

The amount of transmitter within each vesicle

doesn’t vary wildly (e.g. 100 +- 5)

Question 10

Hodgkin and huxley?

Answer 10

squid giant axons!

Question 11

What are autoreceptors?

Answer 11

Receptors sensitive to transmitters.

Lets presynaptic cell know how much neurotransmitter is in the synapse

Found in the edges of synapses

Question 12

If an agonist binds to an autoreceptor, what is the net effect?

Answer 12

antagonism: there’s ‘too much’ agonist in the synapse, so autoreceptor makes less get released

Question 13

If a drug blocks an autoreceptor for agonists, what is the net effect?

Answer 13

Agonism.

Autoreceptor can’t send negative feedback to the presynaptic neuron when there’s too much agonist neurotransmitter in the synapse

Question 14

What are the two major families of neurotransmitters?

Answer 14

Small molecule

Neuropeptide

Question 15

What are the four families of small-molecule transmitters?

Answer 15

Acetylcholine, monoamines, amino acids, soluble gases

Synthesized in terminal or cell body (simple)

Question 16

How is acetylcholine synthesized?

Answer 16

From choline by CHAT (choline acetyltransferase)

Question 17

What are the main receptor types for acetylcholine?

Answer 17

Nicotinic (direct gating/ionotropic) > EPSPs

Muscarinic (indirect gating/metabotropic)

Question 18

What kind of Ach receptors would you see in the neuromuscular junction?

Answer 18

Only nicotinic

Question 19

What kinds of second messenger effects could you see from muscarinic receptors?

Answer 19

inhibition of cyclic AMP formation

Gets vague after that

Question 20

What’s the synthetic pathway for the catecholamines?

Answer 20

Tyrosine >(tyrosine hydroxylase) > L-dopa >(dopa decarboxylase) > dopamine >(dopamine B-hydroxylase) > norepenephrine >(PNMT)> epinephrine

Question 21

What neurotransmitters make up the monoamines?

Answer 21

Dopamine, norepenephrine, epinephrine (EPI) (all catecholamines)

Serotonin (indoleamine)

Question 22

What kind of gating do the monamines have?

Answer 22

Indirect gating (metabotropic), all of them

Question 23

What kind of neurotransmitter is serotonin?

Answer 23

an indoleamine

Question 24

What neurotransmitters make up the amino acids?

Answer 24

Glutamate, GABA

Question 25

What receptor type do the amino acids act on?

Answer 25

Both Indirect-gated (metabotropic) and direct-gated (ionotropic)

Question 26

How are the amino acids inactivated?

Answer 26

Reuptake into neurons/glia

Question 27

How is Ach broken down?

Answer 27

Only extracellularly, choline is taken back up

Question 28

How many peptide neurotransmitters are there?

Answer 28

130+

Question 29

How many peptide neurotransmitters use reuptake?

Answer 29

None.. they're too big to bring back into the presynaptic neuron! Means it's really easy to get depleted

Question 30

How hard is it for serotonin to get depleted?

Answer 30

REAL hard

Question 31

What is the name of the thing a drug preventing storage of NT in vesicles would reduce?

Answer 31

quantal size

Question 32

Is agonist/antagonist mean excitatory/inhibitory?

Answer 32

NO!! Depends on what is being antagonized/agonized

Question 33

When might a peptide transmitter be released? What needs to be happening action potential-wise?

Answer 33

Peptides require more Ca2+ entry Released when a neuron burst-fires, but not at low frequency

Question 34

Neuromodulator

Answer 34

Chemicals without direct effect on postsynaptic cell - might e.g alter action of a standard neurotransmitter by changing its effectiveness

Question 35

Active zone

Answer 35

Area on membrane neurotransmitter is released Vesicles are primed and ready at active zones

Question 36

Will neurotransmitters always be released if an action potential fires?

Answer 36

NO! Sometimes Ca2+ gets to terminal and nothing happens

Question 37

Two different types of autoreceptors

Answer 37

Terminal autoreceptor - on axon terminals, inhibit further ntransmitter release Somatodendritic autoreceptor - on cell body / dendrites, cause cell firing rate to slow

Question 38

What's different about autoreceptors / hetero?

Answer 38

Heteroreceptors: axoaxonic terminals, for receiving neurotransmitter from another neuron

Question 39

What neurotransmitter is enzymatic breakdown important for?

Answer 39

Ach

Question 40

What are transporters? What neurotransmitters are relevent re: them?

Answer 40

Transport neurotransmitter back into cell membrane Glutamate, GABA, monoamines

Question 41

What drugs work by blocking neurotransmitter transporters?

Answer 41

Cocaine (blocks DA, 5-HT, NE) Many antidepressants

Question 42

When are ionotropic receptor subunits assembled?

Answer 42

Before insertion in the cell membrane

Question 43

How many transmembrane domains do metabotropic receptors have?

Answer 43

7 ('7-TM receptors')

Question 44

Metabotropic receptors for which neurotransmitters work by opening K+ channels for hyperpolarization?

Answer 44

Ach, DA, NE, 5-HT, GABA, neuropeptides (e.g endorphins)

Question 45

What do effector enzymes do?

Answer 45

Make second-messengers do shit after being activated by a g-protein