3: Physiology - Excitatory and inhibitory neurotransmission in the CNS Flashcards Preview

Neurology Week 2 2018/19 > 3: Physiology - Excitatory and inhibitory neurotransmission in the CNS > Flashcards

Flashcards in 3: Physiology - Excitatory and inhibitory neurotransmission in the CNS Deck (39)
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1

Given that nerve cells depolarise to cause an action potential, are their resting membrane potentials positive or negative?

Negative

2

Which ion channels open to cause a depolarisation?

Na+

Ca2+

i.e positively charged ions

3

Which ion channels open to cause a hyperpolarisation?

C- (flows inwards, makes cell more negative)

K+ (flows outwards, makes cell more negative)

4

In which directions do

a) sodium

b) calcium

c) chloride

d) potassium

ions flow to cause a/b) depolarisation and c/d) hyperpolarisation?

a) Inwards

b) Inwards

c) Inwards

d) outwards

5

What type of nerve transmission is triggered by a depolarisation?

Excitation

6

What type of nerve transmission is triggered by a hyperpolarisation?

Inhibition

7

Given that sodium influx causes a cell to depolarise, what effect do

a) sodium channel agonists

b) sodium channel antagonists

have on nerve cells?

a) Excitatory

b) Inhibitory

8

Given that potassium efflux causes a cell to hyperpolarise, what effects do

a) K+ channel agonists

b) K+ channel antagonists

have on nerve cells?

a) Inhibition

b) Excitation

9

What is the difference between an axon and a dendrite?

Both are projections of a neuron

Axons carry outputs to other neurons

Dendrites receive inputs from other neurons

Neurons have many dendrites but only one axon

10

What is the space between a pre-synaptic cell and a post-synaptic cell called?

Synaptic cleft

11

Which ion is essential in triggering the release of neurotransmitters across a synaptic cleft?

Ca2+

12

What releases neurotransmitters into the synaptic cleft?

What transport process is this an example of?

Synaptic vesicle

Exocytosis

13

By which three means are neurotransmitters cleared from the synaptic cleft?

1. Recycling into axon terminal or glial cell

2. Deactivation by enzymes

3. Diffusion out of synaptic cleft

14

Which types of receptors

a) directly

b) indirectly

activate ion channels as a result of the binding of neurotransmitters?

a) Direct receptors for ligand-gated channels

b) G-protein coupled receptors

15

What is faster, direct or indirect gating of ion channels?

direct gating

ligand binds to receptor, response

where as indirect gating involves proteins and metabolites which have to react and change confirmation etc etc

16

What is the main excitatory neurotransmitter?

Glutamate

17

What are the main inhibitory neurotransmitters?

GABA

Glycine

18

Molecules called AMPA and NMDA are sometimes found bound to glutamate (excitatory) receptors.

What happens to the speed of the neurotransmision when NMDA is bound?

Slows down - "slow component"

19

What happens to the speed of neurotransmission at a glutamate (excitatory) receptor when AMPA is bound?

Speeds up - rapid transmission

20

What are the main inhibitory neurotransmitters?

GABA

Glycine

21

What are ionotropic and metabotropic receptors?

Ionotropic - directly gated by ions which bind to them to cause a response e.g channel opening

Metabotropic - indirectly gated - binding by a ligand causes a chemical reaction / protein release etc. etc. which eventually opens the channel

22

Which type of receptor is faster acting - ionotropic or metabotropic?

Ionotropic

23

Ionotropic receptors are often responsible for ___ an action potential at the post-synaptic terminal.

triggering

24

Because metabotropic receptors are slower acting than ionotropic receptors, which role do they have in a synapse?

Alter PROPERTIES of action potential e.g firing rate, amplitude

Alter neurotransmitter release

25

In general, ionotropic receptors trigger (fast / slow) action potentials.

ionotropic - fast action potentials

26

In general metabotropic receptors trigger (fast / slow) action potentials.

metabotropic - slow action potentials

27

What is the name of the action potential triggered by neurotransmitters in the neuron FOLLOWING a synapse?

Post-synaptic potential

28

What must the post-synaptic potential overcome to trigger an action potential?

Threshold potential

29

In terms of threshold potential, what is meant by an excitatory or inhibitory post-synaptic potential?

Excitatory - depolarises the neuron and brings it closer to the threshold potential required for an AP

Inhibitory - hyperpolarises the neuron and brings it further away from threshold

30

What variable determines the amplitude of an AP generated by sensory neurons?

Stimulus intensity