chapter 4 Flashcards

1
Q

describe the resting membrane potential

A

polarized

-70mV

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2
Q

How can you record membrane potential?

A

comparisons of intracellular and extracellular electrode readings

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3
Q

what did Hodgkin and Huxley experiment on?

A

-giant squid motor neurons

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4
Q

how are sodium ions distributed?

A
  • higher outside the cell
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5
Q

describe the resting membrane in relation to chloride ions

A
  • concentration is higher outside the cell but only slightly resisted
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6
Q

describe the potassium concentrations in relation to resting potential

A

concentration is higher inside driven inside by electrostatic pressure but driven out by concentration gradient

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7
Q

what is concentration gradient?

A

tends to equally distrubute by moving high to low concentration

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8
Q

what is electrostatic pressure?

A

attractive forces between opposite charges and repelling forces between like charges

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9
Q

what are non-homogenizing factors to maintain resting potential?

A

passive and active movement

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10
Q

what is passive movement?

A

random motion due to selectively permeable ion channels

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11
Q

what is active transport?

A

sodium potassium pumps that maintain stability of resting potential in spite of random motion

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12
Q

what do post synaptic potentials do?

A

create signals in neurons

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13
Q

what do excitatory neurotransmitters do?

A

depolarization to make the membrane potential less negative

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14
Q

what do excitatory post synaptic potentials do?

A

increase the likelihood of an action potentials

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15
Q

what do inhibitory neurotransmitters do?

A

hyperpolarize the cell and make membrane potential more negative

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16
Q

what do inhibitory post synaptic potentials do?

A

decrease the likelihood of action potentials

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17
Q

what is the rate of EPSPs and IPSPs?

A

instantaneous rate of transmission with variable duration

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18
Q

describe amplitude of grade potentials

A

proprotional to signal intensity

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19
Q

describe transmission of graded potential

A

decremental transmission that is from weakening passive spread

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20
Q

what is responsible for generation of EPSPs?

A

sodium influx

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21
Q

what is responsible for IPSPs?

A

chloride influx

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22
Q

how are postsynaptic potentials integrated?

A

adding or combining signals into one overall output

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23
Q

what is spatial summation?

A

integration across post synaptic locations when local EPSPs and IPSPs occur simultaneously

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24
Q

what is temporal summation?

A

integration across time on the same synapse in rapid succession

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25
Q

what ae action potentials?

A

massive reversal of membrane potential that does not degrade over space

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26
Q

how are action potentials generated?

A

voltage-gated sodium ion channels that open or close in response to the membrane potential

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27
Q

when threshold of activation for action potentials is reached what happens?

A

voltage-gated sodium channels open and sodium rushes in due to electrostatic and concentration gradient

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28
Q

what is the second step during an action potential?

A

voltage-gated potassium channels open and potassium is driven out due to electrostatic and concentration gradient to repolarize cell

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29
Q

what is the absolute refractory period?

A

brief post initiation where it is impossible to to initiate new action potentials due to inactive sodium channels

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30
Q

what does the absolute refractory period do?

A

prevents backwards motion of action potentials and limits firing rate

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31
Q

what is the relative refractory period?

A

follows absolute period and requires larger than threshold stimulus to initiate new action potentials

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32
Q

describe conduction of an AP

A

active and passive nondecremental

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33
Q

anterograde conduction

A

from hillock to boutons

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34
Q

retrograde conduction

A

boutons to hillock

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35
Q

orthodromic conduction

A

anterograde

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36
Q

antidromic conduction

A

retrograde conduction

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37
Q

describe conduction in myelinated axons

A

instant conduction along myelin with passive, saltatory conduction

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38
Q

when is axonal conduction fater?

A

in larger, myelinated neurons

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39
Q

describe conduction in interneurons

A

passive and decremental that functions to integrate neural activity in brain structure

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40
Q

what are some differences in cerebral neurons from squid motor neurons?

A

fire AP continually, duration, frequency, and amplitude differ, dendrites can conduct APs

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41
Q

directed synapse

A

site of neurotransmitter release close to post synaptic contact

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42
Q

undirected synapse

A

site of release and contact for varicosities that is common for monoamines and neuroendocrine system

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43
Q

first step of chemical transmission of signals

A

AP reaches end of axon terminal

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44
Q

second step of chemical transmission of signals

A

calcium enters the cell

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45
Q

third step of chemical transmission

A

release of neurotransmitter into the cell

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46
Q

fourth step of chemical transmission

A

receptors influnece post synaptic neurons

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47
Q

inotropic refers to

A

ion permeability

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48
Q

metabotropic refers to

A

intracellular signalling

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49
Q

sixth step of chemical transmission

A

neurotransmitter degradation and recycling

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50
Q

small molecule neurotransmitter synthesis

A

enzymatic conversion of amino acid precursors

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51
Q

large molecule neurotransmitter synthesis

A

peptides that are processed by enzymes

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52
Q

where are small molecule NT synthesized

A

cytoplasm and golgi apparatus

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53
Q

how are small molecules NT’s released?

A

in pulses for each action potential

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54
Q

where are large molecule NT’s released?

A

into extracellular fluid and ventricles for bloodstream

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55
Q

where are large molecule NT’s synthesized?

A

cell body, packaged in vesicles and trasported with cytoskeletons to terminal

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56
Q

describe packaging of NT’s

A

proteins are syntehsized in rough endoplasmic reticulum then transported to the golgi where they bud off the golgi to form vesicles and transporter proteins actively pump NT’s into them after anterograde axonal transport

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57
Q

what are small clear core vesicles?

A

contain the small molecule NT’s

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58
Q

what are large dense core vesicles?

A

contains the neuropeptides of 90-250 diameter

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59
Q

what is coexistence?

A

when more than one type of NT is synthesized and released in neurons

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60
Q

what is anterograde to axon terminal transport of neurotransmitters?

A

motor proteins of kinesin use steps of attachment/ detachment; microtubules highway system

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61
Q

what does transport of NT require?

A

energy and calcium

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62
Q

how are NT’s released?

A

AP in axon terminals that opens voltage-gated calcium channels clustered in the active zone and activate proteins

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63
Q

what do the active proteins in neurotransmitters release do?

A

mobilize vesicles and fuse vesicles with synaptic membrane

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64
Q

what is vesicle recapturing?

A

local resynthesis of synaptic vesicles

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65
Q

where are NT receptors?

A

in presynaptic and postsynaptic cells

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66
Q

how do NT receptors work?

A

each is specific for the NT and there are multiple receptor sub-types for each but act differently in different areas of the brain

67
Q

what are ionotropic receptors?

A

ligand-gated ion channels that are fast-acting and can generate EPSPs and IPSPs and are found post synaptically

68
Q

what are metabolic receptors?

A

slow acting and long lasting changes that have more varied and diffuse effects

69
Q

what are neuropeptide receptors?

A

metabotropic receptors

70
Q

where are metabotropic receptors found?

A

pre and post synaptically for inhibition and facilitation at the presynaptic site

71
Q

what is the anatomy of an ionotropic channel?

A

an ion channel with action lasting as long as the NT is around

72
Q

what is the anatomy of a metabotropic channel?

A

it crosses the cell membrane seven time and has a pocket for the NT to bind to the G protein to be activated

73
Q

how do ionotropic receptors act?

A

through EPSPs or IPSPs summated to initiated or inhibit AP generation in post synaptic cell

74
Q

how do metabotropic systems act?

A

with a NT as a first messenger and then initiate a second messenger which initiates intracellular cascades

75
Q

what are the effects of metabotropic receptors?

A

long lasting changed and various effects due to the types of G protein coupled to the receptor

76
Q

what is often the presynaptic effect of metabotropic receptors?

A

an increase in NT’s

77
Q

what is often the postsynaptic effect of metabotropic receptors?

A

increase in proteins that go do things

78
Q

what are autoreceptors?

A

metabotropic receptors that auto respond to their own NT released from the presynaptic site

79
Q

what is the function of autoreceptos?

A

providing feedback to NT concentrations

80
Q

what are the ways of stopping NT’s

A

reuptake or enzymatic degradation

81
Q

what is responsible for reuptake?

A

transporters on cell neurons/ glia that pick up the NT from synapse

82
Q

what happens after reuptake?

A

repackaging into vesicles or intracellular degradation to execute monoamines

83
Q

what could precursors be used for?

A

NT synthesis or energy

84
Q

what does NT degradation happen?

A

when NTs do not have transporters for reuptake

85
Q

what is the effect of pesticides?

A

inhibiting the ability of acetylcholinesterase to degrade acetylcholine

86
Q

what is the effect of low doses to inhibit acetylcholine?

A

helps alzheimer’s patients to have more acetylcholine

87
Q

what is an example of an NT that is degraded intracellularly?

A

dopamine

88
Q

what is NT recycling?

A

reuptake can provide more NT to be repackaged and released immediately or can be broken down into different NTs

89
Q

what is the distribution of astrocytes?

A

even distribution of domains with very little overlap

90
Q

how do astrocytes act in synaptic transmission?

A

through coordinated activity with gap junctions that allows them to modulate NT activity

91
Q

what does the tripartic synapse refer to?

A

presynaptic, post synaptic and astrocyte cell

92
Q

what is a specific example of astrocyte involvement in synaptic transmission?

A

uptakes glutamate to reduce excitotoxicity, and stimulate energy provision to nuron which produces locatate that maintains activity.

93
Q

what are gap junctions made of?

A

a protein called connexin

94
Q

what is the function of gap junctions?

A

to connect cytoplasm of two adjacent cells and allow electrical synapse

95
Q

what are amino acid NTs?

A

small molecule NTs that allow for fact acting directed synapses and are byproducts of intermediary metabolism

96
Q

what are excitatory amino acids NTs?

A

NTs carrying 2 negative charged

97
Q

where do excitatory amino acid NTs act

A

dendrites

98
Q

what are examples of excitatory amino acid NTs?

A

glutamate and aspartate

99
Q

where is glutamate found?

A

most commonly in the CNS

100
Q

what is the effect of glutamate on ionotopic receptors?

A

induce EPSP through sodium, potassium, and calcium

101
Q

where does glutamate act metabotropically?

A

Gs and Gq proteins

102
Q

Describe normal NMDA receptor transmission

A

presynaptic glutamate and post synaptic depolarization as it displaces the magnesium block, allowing calcium into the cell

103
Q

describe inhibition of NMDA receptor through ketamine

A

Channel is blocked by ketamine and calcium cannot enter the cell

104
Q

what is the evidence for depression being a disease of plasticity?

A

after ketamine blockage of NMDA channels, the cell is forced to make a bunch of changes to allow calcium into the cell

105
Q

describe inhibitory amino acid NTs?

A

carry one negative charge

106
Q

where do inhibitory amino acid ATs act?

A

the soma is the major receiving area

107
Q

what are examples of inhibitory amino acid NTs?

A

GABA, glycine

108
Q

where is GABA found?

A

CNS

109
Q

what receptors does GABA act on?

A

interneurons, ionotropic, and metabotropic

110
Q

what is the effect of GABA on ionotropic receptors?

A

inhibitory through chloride influx or potassium efflux

111
Q

what does GABA act on metabotropically?

A

Gi proteins

112
Q

where is glycine found?

A

spinal cord

113
Q

what is epilepsy due to?

A

too much glutamate and not enough GABA

114
Q

what are glutamates and GABA important for?

A

learning and memory

115
Q

what are the categories of monoamine NTs?

A

catecholamines, indolamines, histamines

116
Q

what are examples of catecholines?

A

dopamine, norepinephrine, epinephrine

117
Q

what is characteristic of catecholines?

A

precursor is tyrosine

118
Q

what are indolamines?

A

melatonin, serotonin

119
Q

what is characteristic of indolamine?

A

tryptophan precursor

120
Q

how do monoamine NTs act?

A

diffused effects through metabotropic receptors that are released by varicosities

121
Q

what is the role of catecholamines?

A

modulators in PNS and CNS

122
Q

where is epinephrine found?

A

only released in PNS sympathetic to increase energy availability

123
Q

where are norepinephrine and dopamine found?

A

CNS and PNS but cannot cross the blood brain barrier

124
Q

what is norepinephrine for?

A

modulatory effects related to stress/anxiety , vigilance, vigilance, and attention

125
Q

where is norepinephrine found?

A

locus coereleus

126
Q

where is dopamine found?

A

nigrostriatal system, dorsal mesostriatal pathway, mesolimbic cortical, periventricular, tuberal hypophyseal

127
Q

what is the effect of dopamine in nigrostriatal system?

A

movement and reward

128
Q

what is the effect of dopamine on dorsal mesotriatal pathways?

A

movement initiation

129
Q

what is the effect of dopamine on dorsal mesotriatal pathways?

A

movement initiation

130
Q

what is the effect of dopamine on ventral nigrostriatal pathways?

A

positive incentive/ reward

131
Q

what is the effect of dopamine of mesolimbic pathways?

A

projections to limbic structures with a role in schizophrenia and parkinsons

132
Q

what is the effect of dopamine on periventricular pathways?

A

motivated behaviours, originates in hypothalamus

133
Q

what is the effect of dopamine on tuberal hypophyseal pathways?

A

lactation

134
Q

not enough dopamine in PFC results in what?

A

negative cognitive symptoms associated with PD

135
Q

what is the effect dopamine in PFC results in what?

A

positive symptoms related to schizophrenia

136
Q

where do dopamine neurons carry signals?

A

brainstem to midbrain and PFC

137
Q

where is serotonin located?

A

Raphe nuclei and caudal system

138
Q

what does raphe nuclei do with serotonin?

A

provides 80% to forebrain

139
Q

what does the caudal system do with serotonin?

A

sensory and motor function in spinal cord

140
Q

what does serotonin have a role in

A

appetite, sleep and aggression

141
Q

what does melatonin do?

A

regulates circadian rhythms by fluctuating with light cycles to signal seasonal day length

142
Q

where does ACh predominantly act?

A

Neuromuscular junction

143
Q

what is the effect of botox?

A

inhibits the release of ACh to inhibit muscle contraction

144
Q

what does curare do?

A

inhibitor of ionotropic receptors of ACh that causes paralysis

145
Q

what are receptors of ACh?

A

Nicotinic and muscarinic

146
Q

What is the nicotinic receptor

A

motor receptor NMU

147
Q

what is the muscarinic receptor?

A

metabotropic receptor in ANS

148
Q

what does ACh have a role in?

A

learning and memory including alzheimer’s and dietary choline

149
Q

what is atropine?

A

mAchR antagonist that inhibits the parasympathetic system causing memory disorders

150
Q

what are unconventional NT’s?

A

soluble gases

151
Q

where are soluble gases synthesized?

A

neural cytoplasm

152
Q

what do soluble gases do?

A

retrograde transmission with rapid diffusion to extracellular fluid with a role in controlling brain blood flow

153
Q

describe endocannabinoid?

A

inhibitory metabotropic receptors with a role in pain reduction, increased appetite, and retrograde transmission

154
Q

what are the groups of neuropeptides?

A

pituitary, hypothalamus, brain-gut opioid, misc

155
Q

what do pituitary neuropeptides do?

A

release from pituitary gland and do not reenter brain

156
Q

what do hypothalamus neuropeptides do?

A

release into pituitary and throughout brain to control behaviour

157
Q

what do brain-gut neuropeptides do?

A

feeding behaviours and can cross bbb

158
Q

what do opioid neuropeptides do?

A

endorphins released from periaqueductal gray to regulate pain and stress

159
Q

what does behavioural pharmacology do?

A

provides treatments for neurological or neuropathological disorders by drugs targeting specific receptors

160
Q

what does drug addiction depend on?

A

ease of crossing the bbb

161
Q

where does drug addiction act?

A

mesotelencephalic dopamine system

162
Q

what are endogenous opiods?

A

endorphin and enhephalin

163
Q

what are exogenous opioid?

A

from opium poppy

164
Q

where do opioid act?

A

periqueductal gray, hypothalamus, limbic system