Synaptic integration in the CNS Flashcards

1
Q

What are examples of neurons in the CNS receiveing excitatory and inhibitory input (3)

A
  1. DTR/MSR
  2. Motor control
  3. Pain modulation
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2
Q

Where are motor neurons located

A

In the anterior horns of the gray matter

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3
Q

True or False:

A single motor neuron may be innervated by up to 10,000 different presynpatic endings

A

True

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4
Q

True or False:

The generation of an action potential at the axon hillock depends on the integration of both signals

A

True

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5
Q

Where does an axosomatic synapse occur

A

At the cell body (soma)

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6
Q

Where does an axodendritic synapse occur (2)

A
  1. Dendritic spine

2. Dentritic shaft

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7
Q

Where does an axo-axonic synapse occur

A

At the axon

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8
Q

What are the 2 types of synapses

A

Type I and type II

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9
Q

What do type II synapses tend to be

A

Inhibitory

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10
Q

What do type I synapses tend to be

A

Excitatory

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11
Q

What type of synapses has a thicker post synaptic density

A

Type I

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12
Q

Why do synapses occur at different locations

A

So we can have presynaptic facilitation of signal

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13
Q

What is back propagation

A

Generating potentials back to where they were formed

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14
Q

What causes back propagation

A

Voltage gated Na+ channels

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15
Q

Where is the highest amount of voltage gated Na+ channels

A

The axon hillock

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16
Q

What is back propagation important for

A

Learning and memory

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17
Q

How does the back propagation potential look in relation to the action potential

A

The peak is not as high and it is more spread out

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18
Q

Why does the potential formed by back propagation have a lower peak

A

We don’t have many voltage gated Na+ channels in the dendrites

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19
Q

Why does the potential go backwards

A

There is propagation of the potential in both directions

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20
Q

The further away you are from the axon hillock what needs to occur for an action potential to take place

A

The stimulus needs to be greater

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21
Q

True or False:

A stimulus from the dendrites is able to initiate an action potential that occurs later down the axon

A

True

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22
Q

What happens to an excitatory synpatic potential as it travels toward the soma

A

The potential decreases

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23
Q

What is the time constant

A

How fast the stimulus dissipates

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24
Q

What is the length constant

A

How far does the stimulus travel before it dissipates

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25
Q

What does temporal summation relate to

A

The time constant

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26
Q

What does spatial summation relate to

A

The length constant

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27
Q

What is temporal summation

A

The process of adding consecutive synaptic potentials together

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28
Q

What is spatial summation

A

The process of adding presynaptic potentials together from multiple locations on the axon

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29
Q

What happens if something has a long time constant

A

Stimuli are able to summate leading to an action potential

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30
Q

What happens if something has a short time constant

A

The stimulus dissipates faster leading to no action potential

31
Q

What happens if something has a long length constant

A

The stimuli is able to travel longer adding together leading to an action potential

32
Q

What happens if something has a short length constant

A

The stimuli can’t add leading to no action potential

33
Q

Does a stimulus with a long or short length constant have the ability to prevent the stimulus from leaking out

A

Long length constant

34
Q

What does presynaptic facilitation do

A

Allows for more NT release from the presynaptic cell

35
Q

What does presynaptic inhibition do

A

Allows less NT release from the presynaptic cell

36
Q

What does presynaptic facilitation enhance

A

Influx of Ca++

37
Q

What causes the enhanced influx of Ca++ during presynaptic facilitation (2)

A
  1. Inactivation of K+ channels

2. Activation of ionotropic receptors on the presynaptic membrane permeable to Ca++

38
Q

What does inactivating K+ channels cause

A

Longer duration of the presynaptic AP

39
Q

What does presynaptic inhibition reduce

A

Influx of Ca++

40
Q

What causes the reduced influx of Ca++ during presynaptic inhibition (2)

A
  1. Activation of ionotrpoic GABA receptors on the presynaptic membrane
  2. Activation of GPCR which modulates ion channel activity
41
Q

Why does activating GABA receptors reduce the influx Ca++

A

GABA receptors are inhibitors

42
Q

How can you inhibit a patients pain during an exercise

A

By talking to them distracting their mind from the pain

43
Q

How can you facilitate a patients pain during an exercise

A

By having them focus extremely hard on the exercise

44
Q

What do you do if someone is ticklish

A

Have the patient put their hand where you are doing the intervention

45
Q

What determines the effects we get in the post synaptic cell

A

The receptors that are on the post synaptic membrane

46
Q

EPSP are mediated by ionotropic glutamate receptors that are permeable to what (2)

A
  1. NA+

2. K+

47
Q

What is the co-factor to glutamate

A

Glycine

48
Q

What does opening of NMDA receptors depend on (2)

A
  1. Voltage

2. Glutamate

49
Q

What does voltage do to NMDA receptors

A

Causes Mg++ to be removed from the receptor pore

50
Q

How do AMPA and NMDA glutamate receptor channels contribute to the EPSP current

A

When AMPA and NMDA are able to work together the flow of currents is prolonged

51
Q

When is NMDA less effective a more positive or negative membrane potential

A

More negative

52
Q

How many NMDA and AMPA receptors does the post-synaptic density usually contain

A

NMDA: 20
AMPA: 10-50

53
Q

Where are NMDA and AMPA receptors located in the post-synaptic density

A

NMDA: the most centrally located
AMPA: Centrally located just not as central as NMDA

54
Q

Where are metabotropic glutamate receptors located in the psot-synaptic density

A

The outside

55
Q

What is responsible for anchoring the NMDA receptor down

A

PSD 95

56
Q

What is responsible for anchoring AMPA

A

TARP

57
Q

True or False:

TARP and PSD 95 interact with one another

A

True

58
Q

Where is neuroxin located

A

Presynapatic cell

59
Q

What does neuroxin do

A

Interacts with neuroligin

60
Q

True or False:

Inhibitory synapses play an important role in the CNS

A

True

61
Q

What role do inhibitory synapses play in the CNS (2)

A
  1. Preventing too much excitation

2. Coordinate activity among networks of neurons

62
Q

What is the major inhibitory NT in the brain

A

GABA

63
Q

What are the major inhibitory NT in the spinal cord (2)

A
  1. GABA

2. Glycine

64
Q

What does an inhibitory interneuron do

A

Prevents excess excitation

65
Q

GABA a is what type of receptor

A

Ionotropic

66
Q

GABA b is what type of receptor

A

Metabotropic

67
Q

What does the effect of an inhibitory current in the postsynpatic neuron depend on

A

The distance the current travels from the synapse to the trigger zone

68
Q

What does the size of the IPSP depend on

A

The location of stimulation

69
Q

What happens to the IPSP as it propagates up the dendrite

A

IT decyas

70
Q

What happens if the IPSP occurs at the soma

A

Significant hyperpolarization

71
Q

What happens if the IPSP occurs at the dendrite

A

There is minimal hyperpolarization

72
Q

Keys to know for test (6)

A
  1. Neurons receive excitatory and inhibitory input
  2. Generation of an action potential depends on time and length constants
  3. Excitatory synapses tend to be located on spines of dendrites
  4. Presynaptic mechanisms influence generation of APs
  5. Inhibitory synapses tend to be located at the cell bodies and axons
  6. EPSPs and IPSPs depend on the receptors located on the post-synaptic membrane
73
Q

What are AMPA receptors permeable to (2)

A
  1. Na+

2. K+

74
Q

What are NMDA receptors permeable to (3)

A
  1. Na+
  2. K+
  3. Ca++