Synapses and neurotransmitters 2

Question 1

What is the criteria for a neurotransmitter?

Answer 1

Present in synaptic vesicles
Released in response to stimulation
Act on the post synaptic neuron

Question 2

What does blocking the neurotransmitter prevent?

Answer 2

Synaptic transmission

Question 3

What are 3 classes of neurotransmitter?

Answer 3

Amino acids
Amines
Peptides

Question 4

What do peptide releasing hormones also sometimes release?

Answer 4

A small molecule transmitter called a ‘co-transmitter’

Question 5

What can amino acids and amine neurotransmitters bind to?

Answer 5

Ligand gated ion channels
G protein coupled receptors

Question 6

What can peptide neurotransmitters bind to?

Answer 6

G protein coupled receptors

Question 7

Where are amino acids and amine neurotransmitters stored?

Answer 7

In synaptic vesicles

Question 8

Where are peptide neurotransmitters stored?

Answer 8

Secretory granules

Question 9

What is a ionotropic receptor?

Answer 9

Ligand gated ion channels that directly depolarise or hyperpolarise the postsynaptic cell

Question 10

What is a metabotropic receptor?

Answer 10

G protein coupled receptor which can produce second messengers and cause biochemical changes throughout the cell

Question 11

Is glutamate an excitatory or inhibitory neurotransmitter?

Answer 11

An excitatory

Question 12

Where is Glutamate found?

Answer 12

In CNS, in all neurons

Question 13

How is glutamate action terminated?

Answer 13

Selective reuptake into presynaptic terminals and glia

Question 14

What are the 3 ionotropic receptors glutamate can act on?

Answer 14

AMPA
NMDA
Kainate

Question 15

What does glutamate binding to AMPA receptors trigger?

Answer 15

Na+ and K+ currents, resulting in an EPSP

Question 16

What do NMDA receptors often co exist with?

Answer 16

AMPA receptors

Question 17

When do NMDA receptors open?

Answer 17

When the cell is already depolarised
- due to voltage dependent Mg2+ block

Question 18

What ion is NMDA permeable to ?

Answer 18

Ca2+ ions

Question 19

What is a coincidence factor?

Answer 19

A neuron that is activated right after a previous activation

Question 20

What is the mechanism for a metabotropic glutamate receptors?

Answer 20

Activates G proteins which triggers a downstream signalling cascade

Question 21

What is the consequence of mGluRs?

Answer 21

Allow glutamate to be inhibitory once G proteins are activated

Question 22

Glutamic acid + Glutamic acid decarboxylase -> ?

Answer 22

Glutamate

Question 23

How is GABA action terminated?

Answer 23

Selective uptake into presynaptic terminals and glia

Question 24

What is the most common inhibitory transmitter in CNS?

Answer 24

GABA

Question 25

What will GABA produce if the membrane potential is above chloride's Nernst potential?

Answer 25

IPSPs via GABA A receptors

Question 26

What would occur in the event of too little GABA inhibition?

Answer 26

Seizures

Question 27

What would occur in the even of too much GABA inhibition?

Answer 27

Come or loss of consiousness

Question 28

What are the downstream effects of GABA + GABA receptor?

Answer 28

Chloride channels open Membrane potential gets closer to chloride Nernst potential

Question 29

What is an allosteric drug?

Answer 29

A drug which has no effect without binding

Question 30

Name 4 allosteric drugs which modulate GABA A receptors

Answer 30

Ethanol Benzodiazepine Barbiturates Neurosteroids

Question 31

Describe the function of GABA B receptor.

Answer 31

Open K+ channels Close Ca2+ channels Trigger other second messengers (cAMP)

Question 32

Function of glycine?

Answer 32

Inhibits neurons via glycine gated chloride channels Binds NDMA to glutamate receptors

Question 33

Describe dendritic integration

Answer 33

Neurons receive inhibitory or excitatory signals on dendrites -> EPSP is produced and propagates along the dendrite and arrive at the soma -> Axon initial segment initiates the ap -> The ap is actively regenerated and sent down the axon

Question 34

When wont GABA A produce a IPSP?

Answer 34

If Vm is near the chloride Nernst potential

Question 35

If GABA A receptors cant produce an IPSP, how do they act?

Answer 35

Via shunting inhibition

Question 36

What is shunting inhibition?

Answer 36

Opening chloride conductance which decreases the membrane and the current is able to leak out

Question 37

Describe presynaptic inhibition

Answer 37

Action potential arrives at the presynaptic terminal -> At the same time, an ap arrives at presynaptic terminal of GABAergic neuron. GABA released onto neuron activates GABA B receptors which inactivated calcium channels -> Less calcium binding means less neurotransmitter released -> Causes a reduced effect on the postsynaptic neuron

Question 38

What is the purpose of inhibition?

Answer 38

Organisation of neurons

Question 39

If AMPA receptors are permeable to both Na+ and K+, why does activating them cause depolarisation?

Answer 39

Na+ flow into the cell whereas only a few K+ leave the neuron, causing an overall depolarisation.

Question 40

What would happen if GABA open GABA A receptors and the membrane potential is below chloride's Nernst potential?

Answer 40

The membrane would depolarisation - Net outflow of chloride ions