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

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

1
Q

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

A

Negative

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2
Q

Which ion channels open to cause a depolarisation?

A

Na+

Ca2+

i.e positively charged ions

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3
Q

Which ion channels open to cause a hyperpolarisation?

A

C- (flows inwards, makes cell more negative)

K+ (flows outwards, makes cell more negative)

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4
Q

In which directions do

a) sodium

b) calcium

c) chloride

d) potassium

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

A

a) Inwards

b) Inwards

c) Inwards

d) outwards

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5
Q

What type of nerve transmission is triggered by a depolarisation?

A

Excitation

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6
Q

What type of nerve transmission is triggered by a hyperpolarisation?

A

Inhibition

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7
Q

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

a) Excitatory

b) Inhibitory

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8
Q

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

a) Inhibition
b) Excitation

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9
Q

What is the difference between an axon and a dendrite?

A

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

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10
Q

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

A

Synaptic cleft

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11
Q

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

A

Ca2+

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12
Q

What releases neurotransmitters into the synaptic cleft?

What transport process is this an example of?

A

Synaptic vesicle

Exocytosis

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13
Q

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

A

1. Recycling into axon terminal or glial cell

2. Deactivation by enzymes

3. Diffusion out of synaptic cleft

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14
Q

Which types of receptors

a) directly
b) indirectly

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

A

a) Direct receptors for ligand-gated channels

b) G-protein coupled receptors

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15
Q

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

A

direct gating

ligand binds to receptor, response

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

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16
Q

What is the main excitatory neurotransmitter?

A

Glutamate

17
Q

What are the main inhibitory neurotransmitters?

A

GABA

Glycine

18
Q

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?

A

Slows down - “slow component”

19
Q

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

A

Speeds up - rapid transmission

20
Q

What are the main inhibitory neurotransmitters?

A

GABA

Glycine

21
Q

What are ionotropic and metabotropic receptors?

A

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
Q

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

A

Ionotropic

23
Q

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

A

triggering

24
Q

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

A

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

Alter neurotransmitter release

25
Q

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

A

ionotropic - fast action potentials

26
Q

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

A

metabotropic - slow action potentials

27
Q

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

A

Post-synaptic potential

28
Q

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

A

Threshold potential

29
Q

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

A

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
Q

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

A

Stimulus intensity

31
Q

What is meant by the term graded potential?

A

A gradual change in membrane potential rather than a sharp jump

32
Q

Why does the graded potential of a neuron decrease?

A

Time - ion channels open and close

Distance - charge leaks away

33
Q

If a graded potential overcomes threshold, what does it become?

A

Action potential

34
Q

What neurotransmitters cause depolarisation of the post-synaptic neuron?

A

Glutamate - excitatory neurotransmitter

35
Q

Which neurotransmitters cause hyperpolarisation of the post-synaptic neuron?

A

GABA

Glycine

36
Q

What is an interneuron?

Which neurotransmitter does it secrete?

A

An independent neuron which processes local information

GABA (inhibitory)

37
Q

What is a quanta of neurotransmitter?

A

The volume secreted from ONE synaptic vesicle

38
Q

What influences the number of quanta of neurotransmitter secreted by a synaptic vesicle?

A

Stimulus intensity

39
Q

From other lectures, what is

a) spatial summation
b) temporal summation?

A

a) Whether a neuron fires or not depends on all the excitatory and inhibitory synapses connected to it

b) Whether a neuron fires or not depends on the number of excitatory / inhibitory signals and the sequence they’re received in

Neurology Week 2 2018/19 (10 decks)

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