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SK298 - Brain, the mind & mental health > Week 3 - Cells of the brain > Flashcards

Week 3 - Cells of the brain Flashcards

1
Q

What are the pathological changes that are prevalent in the brains of patients with Alzheimer’s disease?

A
  • Amyloid plaques
  • Neurofibrillary tangles
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2
Q

What two types of cells can brain cells be broadly categorised as?

A
  • Glial cells
  • Neurons
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3
Q

Roughly how many neurons are there in the brain?

A

86 billion

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4
Q

Is the ratio of glial cells to neurons constant across the brain?

A

No, it varies from region to region

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5
Q

Where are the cell bodies of motor neurons located?

A

Within the brain or spinal cord

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6
Q

Where do the axons of motor neurons carry information from and to?

A

From the brain to the spinal cord and out to effector organs (eg muscles/glands)

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7
Q

Where are granule cells found?

A

In the cerebellum and other brain regions

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8
Q

Which type of cell is one of the most numerous cell types in the brain?

A

Granule cells

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9
Q

Where are pyramidal cells mainly located?

A
  • Cerebral cortex
  • Hippocampus
  • Amygdala
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10
Q

What is the function of pyramidal cells?

A

They carry information long distances within and outside of the brain

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11
Q

Which part of the brain are purkinje cells found in?

A

The outer layer of the cerebellum

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12
Q

Where do purkinje cells transmit information to?

A

Deep within the cerebellum

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13
Q

Which are among the largest cells within the brain?

A

Purkinje cells

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14
Q

What is the function of purkinje cells?

A

They receive and transmit information from other brain areas

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15
Q

What is the function of the dendrites of a neuron?

A

They receive information and pass it on to the cell body for processing

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16
Q

What does the cell body of a neuron do?

A

It integrates information received from neighbouring neurons and processes it before passing it on to other neurons via the axon

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17
Q

What is the myelin sheath?

A

The fatty substance which surrounds and insulates the axon

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18
Q

What is the function of the myelin sheath?

A

It increases the speed that an action potential can travel along the axon

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19
Q

What is a synapse?

A

The junction between neurons which enables information to be passed from one neuron to another

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20
Q

What are the axon terminals?

A

The branches of the axon which form connections with neighbouring neurons

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21
Q

What is the function of an axon?

A

It passes the information from the cell body to the axon terminal

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22
Q

What is an action potential?

A

It is an electrical impulse that allows information to be passed from the cell body to the axon terminal

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23
Q

How large are axons?

A

They can vary widely, some stretch from the foot all the way to the spinal cord, others travel just within one brain region

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24
Q

What is the axon hillock?

A

The area of the neuron where the cell body and the axon form a junction

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25
Q

What is the function of the axon hillock?

A

It is where action potentials are initiated

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26
Q

What is the function of dendrites?

A

They are the main information receivers of the neuron

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27
Q

What are dendrites?

A

They are small branching extensions of the cell body of neurons and receive synaptic connections from other neurons

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28
Q

What is an action potential?

A

An electrical signal which travels along the axon and allows presynaptic neuron to communicate with postsynaptic neuron

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29
Q

How is an action potential often described as?

A

The language of the nervous system

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30
Q

What is a synapse?

A

The junction between the axon terminal of a presynaptic neuron and the dendrite of a postsynaptic neuron

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31
Q

Complete this:
information received at the ____________ is passed on to the ____________ for processing

A
  • Dendrites
  • Cell body
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32
Q

The information from the cell body is passed along which structure to the axon terminal?

A

The axon

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33
Q

In the form of what is information passed from the axon to the axon terminals?

A

An action potential

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34
Q

What feature of a neuron can increase the speed at which an action potential can travel along the neuron?

A

Myelin sheath

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35
Q

At the axon terminal, information is passed from one neron to the dendrites of the next neuron via what?

A

A synapse

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36
Q

Name the four main types of glial cell

A
  • Astrocyte
  • Ependymal cell
  • Oligodendrocyte
  • Microglial cell
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37
Q

Name a function of astrocytes

A

Any of the following:
- Form part of the blood-brain barrier
- Regulate concentration of ions and neurotransmitters around neurons
- Help regulate oxygen and nutrient supplies to neurons
- Play a protective and structural role
- Help regulate the immune and inflammatory responses

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38
Q

Which type of glial cell plays a part in regulating oxygen and nutrient supplies to neurons?

A

Astrocytes

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39
Q

Name a function of ependymal cells

A

Any of the following:
- Filter plasma from the blood to produce CSF
- Aid the circulation of CSF around the central nervous system

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40
Q

Which type of glial cell plays a part in the production of CSF?

A

Ependymal cells

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41
Q

What is the function of oligodendrocytes?

A

They form myelin around axons, which increases the speed of transmission of electrical information

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42
Q

Which type of glial cell is repsonsible for the production of myelin?

A

Oligodendrocytes

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43
Q

Name a function of microglial cells

A

Any of the following:
- Remove bacteria and debris from dead and dying brain cells
- Involved in immunological response to foreign invaders
- Provide growth factors for formation of blood vessels and glial cells

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44
Q

Which type of glial cell is involved in the immunological response to foreign invaders?

A

Microglial cells

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45
Q

Which type of glial cell is involved in providing growth factors for the formation of blood vessels and glial cells?

A

Microglial cells

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46
Q

Why are astrocytes important in the brain?

A

Any of the following:
- Form part of the neurovascular unit
- Influence synaptic transmission
- Mediate immune and inflammatory response
- Involved in the generation of new synapses
- Cause dilation of blood vessels in active brain regions in order to increase blood supply

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47
Q

Which type of glial cell has the most diverse role?

A

Astrocytes

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48
Q

Brains of some patients with major depressive disorder were found to have a reduction in which type of glial cell?

A

Astrocytes

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49
Q

How many other neurons can one neuron form connections with?

A

Up to 15000

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50
Q

What does the term presynaptic refer to?

A

The neuron that is sending out the information

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51
Q

What does the term postsynaptic refer to?

A

The neuron which receives information

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52
Q

What is meant by the term synaptic transmission?

A

The flow of information across a synapse from the presynaptic neuron to the postsynaptic neuron

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53
Q

When an action potential reaches the axon terminal, what are the two potential things it could do (depending on the nature of the synapse)?

A
  • Pass from one neuron to the next via gap junctions
  • Trigger the release of neurotransmitter that influences the postsynaptic neurons
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54
Q

What is a synaptic cleft?

A

The very small space between the presynaptic and postsynaptic neuron

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55
Q

Neurotransmitter is released into the synaptic cleft from what?

A

The presynaptic neuron

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56
Q

What is a synaptic vesicle?

A

The small vesicles at presynaptic terminals which store neurotransmitters

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57
Q

Neurotransmitter is released into the synapse from where?

A

Synaptic vesicle

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58
Q

What is the enlarged region at the end of an axon where neurotransmitter is released?

A

Axon terminal

59
Q

Which area of the postsynaptic neuron receives a signal from the presynaptic neuron?

A

Dendrite

60
Q

What is the name for the packages which contain neurotransmitter ready for release at the synapse?

A

Synaptic vesicles

61
Q

What is neurotransmitter?

A

The signalling molecule that communicates information between neurons via the synapse

62
Q

What are the proteins that are located on the dendrites of the postsynaptic neuron that bind neurotransmitters?

A

Postsynaptic receptors

63
Q

What is the difference between a hormone and a neurotransmitter?

A

A hormone is generally released into the bloodstream and travels round the body to work on organs whereas a neurotransmitter is released from a neuron and acts on neighbouring neurons or other cells in close proximity

64
Q

Where are neurotransmitters synthesised?

A

Either in the axon terminal or in the cell bodies of neurons

65
Q

After being synthesised in either the axon terminal or the cell bodies of neurons, where are neurotransmitters then transported to?

A

The axon terminal

66
Q

After being transported to the axon terminal, why are neurotransmitters then packaged into synaptic vessels?

A

So they can be released in response to an action potential

67
Q

The neurotransmitter dopamine is synthesised from which molecule in the axon terminal?

A

Tyrosine

68
Q

What are neuromodulators?

A

Chemicals which are found in the synaptic cleft which can influence synaptic transmission

69
Q

As well as influencing synaptic transmission, what else can neuromodulators influence?

A

The responsiveness of postsynaptic neurons

70
Q

What are some of the key neurotransmitters?

A

Any of the following:
- GABA
- Glutamate
- Catecholamines such as dopamine and noradrenaline
- Serotonin

71
Q

The neurotransmitter GABA has which type of effect, inhibitory or excitatory?

A

Inhibitory

72
Q

The neurotransmitter glutamate has which type of effect, inhibitory or excitatory?

A

Excitatory

73
Q

What is excitatory postsynaptic potenial (EPSP)?

A

An electrical charge in a postsynaptic neuron which brings it closer to the threshold for firing an action potential

74
Q

What is inhibitory postsynaptic potential?

A

An electrical charge in a postsynaptic neuron which takes it further from the threshold for firing an action potential

75
Q

Which type of postsynaptic potential takes the postsynaptic neuron further away from firing an action potential?

A

Inhibitory postsynaptic potential

76
Q

Which type of postsynaptic potential brings a postsynaptic neuron closer to the threshold for firing an action potential?

A

Excitatory postsynaptic potential

77
Q

How is the frequency of action potential firing defined as?

A

The number of action potentials produced in a given time period

78
Q

What is the frequency of action potential firing used as a measure for?

A

The level of activity in a neuron

79
Q

Does the size of an action potential ever change?

A

No

80
Q

Rather than the size of an action potential changing, what else does instead?

A
  • The frequency of action potentials
  • The number of action potentials produced in a given time
81
Q

What is the order of events which take place at the synapse?

A
  • Action potential reaches the axon terminal
  • Synaptic vesicles fuse with the membrane of the axon terminal, releasing neurotransmitter into the synaptic cleft
  • Neurotransmitter diffuses across the synaptic cleft and binds on the postsynaptic neuron
  • Neurotransmitter is bound to receptors which results in a change in the excitability of the postsynaptic neuron
  • If the excitation is great enough, an action potential is initiated in the postsynaptic neuron
82
Q

Does dopamine have an inhibitory or excitatory effect?

A

It can be either

83
Q

What is the background firing rate?

A

The low frequency level at which a neuron fires action potentials in the absence of any stimulation

84
Q

What is the effect of making the presynaptic inhibitory neuron more active?

A

The frequency of action potentials in the postsynaptic neuron decreases

85
Q

Along with neurotransmitters influencing the postsynaptic neuron, what else can they influence and how?

A

The presynaptic neuron, by binding to autoreceptors

86
Q

What are autoreceptors?

A

Receptors which are found on the axon terminal of presynaptic neurons which can regulate the release of neurotransmitter

87
Q

What can autoreceptors regulate?

A

The release of neurotransmitter

88
Q

Where are autoreceptors found?

A

On the axon terminals

89
Q

Binding of neurotransmitters to autoreceptors decreases what?

A

The amount of neurotransmitter which is released

90
Q

Can neurotransmitters regulate their own release?

A

Yes

91
Q

How many different ways can neurotransmitters be removed from synapses?

A

Three

92
Q

What is synaptic reuptake?

A

One process by which neurotransmitter can be removed from synapses

93
Q

What are the three mechanisms in which neurotransmitters can be removed from synapses?

A
  • Synaptic reuptake
  • Enzymatic degradation
  • Diffusing away from the synapse, being taken up into astrocytes and metabolised into their constituent molecules
94
Q

What is enzymatic degradation?

A

The process by which enzymes present in the synaptic cleft break down neurotransmitters

95
Q

Excessive levels of neurotransmitter can ______________ to neurons?

A

Be toxic

96
Q

What happens if a drug that blocks the reuptake of a neurotransmitter is introduced into the synapse?

A

The neurotransmitter remains in the synaptic cleft for longer and can therefore have a prologned effect on the postsynaptic neuron

97
Q

What does the term synaptic reuptake mean?

A

The process which helps terminate the action of neurotransmitter

98
Q

How does the process of synaptic reuptake terminate the action of neurotrasmitter?

A

It removes it from the synaptic cleft via specialist channels in the axon terminal

99
Q

How does the process of enzymatic degradation remove neurotransmitter from synapses?

A

Enzymes in the synaptic cleft break down neurotransmitter

100
Q

Neurons which utilise acetylcholine as the principal neurotransmitter are known as what type of neurons?

A

Cholinergic neurons

101
Q

Reduced activity in the cholinergic pathway which originates in the pons and projects towards the hippocampus results in what?

A

Impairment of hippocampal functioning

102
Q

Reduced hippocampal functioning is often a feature of which disease?

A

Alzheimer’s disease

103
Q

How many principal dopaminergic pathways are there in the brain?

A

3

104
Q

What is the dopaminergic pathway which runs from the substantia negra to the caudate nucleus and the putamen important for?

A

The production of movement

105
Q

What is the route of the nigrostriatal pathway?

A

From the substantia nigra in the midbrain to the caudate nucleus and the putamen in the striatum

106
Q

Loss of activity in the nigrostriatial pathway underlies which disease?

A

Parkinson’s disease

107
Q

Where does the mesolimbic pathway run?

A

From the ventral tegmental area of the midbrain to the nucleus accumbens in the ventral striatum

108
Q

What is the name of the dopaminergic pathway which runs from the ventral tegmental area of the midbrain to the nucleus accumbens in the ventral striatum?

A

The mesolimbic pathway

109
Q

What is the route of the mesocortical pathway?

A

It starts in the ventral tegmental area of the midbrain and projects to the prefrontal cortex

110
Q

Together, what are the mesolimbic and mesocortical pathways known as?

A

The reward pathways

111
Q

The reward pathways are involved in which type of behaviour?

A

Addictive behaviour

112
Q

Where do the noradrenergic pathways originate in the brain?

A

A region of the brain stem known as the locus coeruleus

113
Q

Where do the noradrenergic pathways project?

A

From the locus coeruleus in the brain stem down the spinal cord and upwards through many regions of the brain

114
Q

What are the descending noradrenergic pathways involved in the control of?

A

Responses of the autonomic nervous system

115
Q

Descending noradrenergic pathways are important in which type of response?

A

Stress response

116
Q

Where do the ascending noradrenergic pathways project?

A

To the hypothalamus, amygdala, thalamus and widely throughout the cortex

117
Q

The projection of the noradrenergic pathway to the prefrontal cortex is of particular importance in the context of what?

A

Mood disorders

118
Q

Where in the brain do the serotinergic pathways originate?

A

In the raphe nuclei of the brain stem

119
Q

Which regions of the brain do serotinergic pathways project to?

A
  • Cerebellum
  • Hippocampus
  • Prefrontal cortex
  • Widely through the cortex
120
Q

What are some of the roles that serotonergic pathways are involved in?

A
  • Sleep/wake cycle
  • Emotions
  • Mood
121
Q

Selective serotonin reuptake inhibitor drugs act how?

A

By preventing the reuptake of serotonin, so that it remains active in the synapse for longer and continues to exert its effects

122
Q

If more receptors are occupied by serotonin, what happens to the EPSP generated?

A

It increases

123
Q

Increased EPSP due to serotonin reuptake inhibitors has what effect on the action potential firing rate in the postsynaptic neuron?

A

It increases

124
Q

How does the type of drug known as an antagonist exert its effect?

A

It binds to the receptor on the postsynaptic neuron, which can prevent neurotransmitter from binding, meaning that the neurotransmitter cannot exert its effect

125
Q

What are antagonists?

A

Chemical substances which bind to receptors and prevent binding of the neurotransmitter

126
Q

Too much activity in certain pathways might be treated with which type of drug?

A

Antagonists

127
Q

If a dopamine antagonist is present, what happens to the action potential firing rate in the postsynaptic neuron?

A

It is lower

128
Q

If there is a deficit of activity in a certain pathway, which type of drug would be helpful?

A

Agonist

129
Q

Which aspects of synaptic transmission could potentially be altered by drugs?

A
  • Drugs which bind to postsynaptic receptors and autoreceptors
  • Drugs that interfere with the processes which terminate the activity of a neurotransmitter
130
Q

What is meant by the term neuroplasticity?

A

Changes that occur in the brain as a result of:
- Development and ageing
- Learning and experiences
- Disease processes
- Recovery from brain injury

131
Q

What is synaptogenesis?

A

The formation of new synapses between neurons

132
Q

What is the name of the process which removes dendrites from neurons during adolescence and into early adulthood?

A

Denritic pruning

133
Q

What is dendritic pruning?

A

The process by which dendritic spines are removed from dendrites, thus reshaping the connectivity between neurons

134
Q

During which period of life does dendritic pruning peak?

A

Adolescence and into early adulthood

135
Q

What is Hebbian plasticity?

A

A type of neuroplasticity which occurs from prolonged or intense activity in one neuron, which leads to increased responsiveness of the next neuron in the pathway

136
Q

What is the friendly explanation of Hebbian plasticity?

A

“Neurons that fire together, wire together”

137
Q

Which brain imaging technique allows activity across the brain to be measured?

A

fMRI - functional magnetic resonance imaging

138
Q

How do we measure brain activity directly?

A

Electoencephalography (EEG)

139
Q

What is electroencephalography?

A

Recording of electrical activity from the cortex of the brain using an array of sensors applied to the scalp

140
Q

What three things have made the study of consciousness scientifically possible?

A
  • A better definition of consciousness
  • The discovery that consciousness can be experimentally manipulated
  • A new respect for subjective phenomena
141
Q

Correlational studies are used for what purpose?

A

To evaluate relationships between two observations

142
Q

What are some of the techniques that can be used to visualise brain structures?

A
  • Microscopy
  • Brain imaging
  • Electrophysiology
143
Q

What is the name for the process in which a chemical neurotransmitter communicates activity from one neuron to another?

A

Synaptic transmission

SK298 - Brain, the mind & mental health (19 decks)

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