excitatory and inhibatoryneurotransmission in CNS

Question 1

typical resting membrane potential for a neurone?

Answer 1

-70mV

Question 2

describe the basic of neurotransmission?

Answer 2

transporters and ion channels create a distribution of charge so that the interior of the cell is negative.

entry of positive ions or exit of negative ions results in the interior of cell becoming positive, this causes depolarization /excitation

any exit of positive ions or entry of negative ions makes more negative charge inside the cell causing hyperpolarization or inhibition

Question 3

depolarization in neurones lead to what?

Answer 3

release of neurotransmitter

Question 4

for a neurone typically at rest what happens when na+ channels open?

Answer 4

Na+ flows into cells making it more + causing excitation

Question 5

for a neurone typically at rest what happens when Ca+ +channels open?

Answer 5

Ca++ flows into cell making it more + causing excitation

Question 6

for a neurone typically at rest what happens when Cl-channels open?

Answer 6

Cl- flows into cell, making it more negative causing inhibition

Question 7

for a neurone typically at rest what happens when K+ channels open?

Answer 7

K+ flows out of cell making it more negative inside the cell causing inhibition

Question 8

an agonist of Na+ channel will cause..?

Answer 8

excitation because na+ channels will open and make inside cell more positive

Question 9

an antagonist of Na+ will cause?

Answer 9

inhibition because it stops the the channels opening so no flow of Na+ into cells

Question 10

and agonist of K+ channel will cause?

Answer 10

inhibtion because K+ will exit cells making it more negative

Question 11

an antagonist of K+ will cause?

Answer 11

excitation

Question 12

what are the events at the synapse?

Answer 12

1. action potential depolarizes the axon terminal
2. this opens the voltage gated Ca++ channels and Ca++ enters cell
3. the entry of Ca++ triggers the release of neurotransmitter
4. neurotransmitter diffuses across synaptic cleft and binds to receptors on postsynaptic cell
5. a response is then initiated

Question 13

what is the main inhibitory neurotransmitter in the CNS?

Answer 13

GABA

Question 14

what is the main excitatory neurotransmitter in the CNS?

Answer 14

glutamate

Question 15

direct gating is done by?

Answer 15

ionotropic receptors

Question 16

indirect gating is done by?

Answer 16

metabotrophic receptors

Question 17

what are the 2 types of ionotropic glutamate receptors?

Answer 17

NON -NMDA receptors (fast excitatory transmission) and NMDA receptors ( slow excitatory transmission)

Question 18

what 2 types of receptors does GABA act on?

Answer 18

(ionotropic) GABAa (operates CL- channels

metabotrophic) GABAb (operates K+ channels

Question 19

glycine - exciting or inhibiting?

Answer 19

inhibiting- released by interneurones into spinal cord

Question 20

EPSP?

Answer 20

excitatory postsynaptic potential

Question 21

IPSP?

Answer 21

inhibatory postsynaptic potential

Question 22

what is graded potenial?

Answer 22

a change in resting membrane potential by either EPSP or IPSP and is not big enough to cross threshold and results in an action potential

however its strength diminishes over distance

its amplitude increases when Na+ enters the cell

Question 23

graded potential eventually becomes?

Answer 23

action potential

Question 24

factors influencing outcome of neurotransmission?

Answer 24

whether the transmitter is exciting or inhibiting

the neurone may have different receptor types

influence on synapse depends on the distance the current has to travel to the neurones trigger zonne

varying amount of transmitter released

a neurone has multiple synaptic contacts from multiple cells