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Lecture 17 > Flashcards

1
Q

Lecture 1: Membranes, ions & potentials

Objectives:

  • Review the generation of the resting membrane potential
  • Review the generation of the action potential
A

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2
Q

Membrane ion pumps generate an .. … and a …. …. across the membrane

Excitable cells, including neurons, can rapidly change this … …. and thus use it to carry information

A

Membrane ion pumps generate an ION GRADIENT and a VOLTAGE DIFFERENCE across the membrane

Excitable cells, including neurons, can rapidly change this MEMBRANE POTENTIAL and thus use it to carry information

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3
Q

The resting membrane potential

  • Membrane pumps set up .. ….
  • The membrane has .. & … channels
  • Most Na+ channels are … at rest
  • Specific K+ channels (leak channels) remain … at rest
  • K+ ions flow … of the cell
A

The resting membrane potential

  • Membrane pumps set up ION GRADIENTS
  • The membrane has Na+ & K+ channels
  • Most Na+ channels are CLOSED at rest
  • Specific K+ channels (leak channels) remain OPEN at rest
  • K+ ions flow OUT of the cell
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4
Q

The resting membrane potential

  • K+ equilibrium reach when … gradient drive …. is balanced by … drive ….
  • This equilibrium potential for K+ is about ..mV
A

The resting membrane potential

  • K+ equilibrium reach when CHEMICAL gradient drive OUT is balanced by ELECTRICAL drive IN
  • This equilibrium potential for K+ is about -80mV
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5
Q

During the rising phase … enters - cell membrane rapidly …..

Membrane potential becomes …. because Na+ conductance exceeds that of K+

A

During the rising phase Na+ enters - cell membrane rapidly DEPOLARIZED

Membrane potential becomes POSITIVE because Na+ conductance exceeds that of K+

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6
Q

During the falling phase the voltage-gated Na+ channels have …

Delayed voltage gated K+ channels …

K+ leaves the cell causing …

A

During the falling phase the voltage-gated Na+ channels have CLOSED

Delayed voltage gated K+ channels OPEN

K+ leaves the cell causing RE-POLARIZATION

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7
Q

Undershoot because K+ conductance is …. membrane potential towards (-80mV) membrane becomes …. …. due to …..

A

Undershoot because K+ conductance is INCREASED membrane potential towards (-80mV) membrane becomes RELATIVE REFRACTORY due to HYPERPOLARIZATION

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8
Q

Na+ channels open upon depolarization but close again despite continued depolarization referred to as …. ….

Provides a period of … ….

Cannot be activated until …. to … ….

A

Na+ channels open upon depolarization but close again despite continued depolarization referred to as CHANNEL INACTIVATION

Provides a period of ABSOLUTE REFRACTION

Cannot be activated until RETURNED to RESTING POTENTIAL

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9
Q

Molecular analysis of the Na+ channels provides a model to describe its properties

Gate prevents Na+ flux at … … …

Gate opens upon …. (to -40mV)

… enters cell

Channel inactivated when …. portion of channel swings into pore

“plug” removed upon return to .. … …

A

Molecular analysis of the Na+ channels provides a model to describe its properties

Gate prevents Na+ flux at RESTING MEMBRANE POTENTIAL

Gate opens upon DEPOLARIZATION (to -40mV)

Na+ enters cell

Channel inactivated when GLOBULAR portion of channel swings into pore

“plug” removed upon return to RESTING MEMBRANE POTENTIAL

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10
Q

…. Binds to the outside of the channel and prevents it ….

A

TETRODOTOXIN Binds to the outside of the channel and prevents it OPENING

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11
Q

Lecture: Membranes, ions & potentials

Objectives

  • What is a neurotransmitter vesicle and how is it handles at the synapse?
  • What are the difference b/w SSV and LDCV?
  • What are the roles of vesicle-associated proteins?
  • What are mechanisms of neurotransmitter release?
  • How does neurotransmitter release alter changes in stimulation strength?
A

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12
Q

Presynaptic events

Summation may be …
- Multiple input neurons activated

Summation may be …
- Input neuron strongly activated

A

Presynaptic events

Summation may be SPATIAL
- Multiple input neurons activated

Summation may be TEMPORAL
- Input neuron strongly activated

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13
Q

Nerve terminals often contain two types of synaptic vesicle

- …. & ….

A

Nerve terminals often contain two types of synaptic vesicle

- SSV (small synaptic vesicles) & LDCV (secretory vesicles)

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14
Q

SSV contain … neurotransmitters (NT)

LDCV also contain …. NT an ….

LDCV more frequent in …. neurons or …. cells

A 
SSV contain 
CLASSICAL neurotransmitters (NT)

LDCV also contain CLASSICAL NT an NEUROPEPTIDES

LDCV more frequent in NEUROSECRETORY neurons or NEUROENDOCRINE cells

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15
Q

LDCV

… precursors synthesized by …

packaged into vesicles by …

Delivered to nerve terminal by … …

… process en route

Vesicles position at …. release sites

A

LDCV

NEUROPEPTIDE precursors synthesized by ER

packaged into vesicles by GOLGI

Delivered to nerve terminal by AXONAL TRANSPORT

PEPTIDES process en route

Vesicles position at EXTRASYNAPTIC release sites

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16
Q

SSV

Vesicles synthesized by …

Delivered to nerve terminal by … …

enter … …

Become filled w/ .. …

A

SSV

Vesicles synthesized by GOLGI

Delivered to nerve terminal by AXONAL TRANSPORT

enter VESICLE CYCLE

Become filled w/ CLASSICAL NT

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17
Q

SSV

  • may enter one of two … ….
  • A reserve pool associated w/ …

A readily releasable or docked pool at … site

A

SSV

  • may enter one of two VESICLE POOLS
  • A reserve pool associated w/ CYTOSKELETON

A readily releasable or docked pool at ACTIVE site

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18
Q

SSV

Ca+ … through voltage-gated Ca2+ channels triggers … …

SSV membrane recycled by … to … or … … …

A

SSV

Ca+ INFLUX through voltage-gated Ca2+ channels triggers VESICLE EXOCYTOSIS

SSV membrane recycled by ENDOCYTOSIS to ENDOSOME or RESERVE VESICLE POOL

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19
Q

SSV

  • Pumps to generate … gradients
  • Used to power transporters to … ….
A

SSV

  • Pumps to generate H+ gradients
  • Used to power transporters to LOAD NEUROTRANSMITTERS
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20
Q

SSV

Small … binding proteins

Assist in vesicle … & …

Provide an on (..) or off (…) indicator of vesicle location

A

SSV

Small GTP binding proteins

Assist in vesicle TARGETING & DOCKING

Provide an on (GTP) or off (GDP) indicator of vesicle location

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21
Q

SSV

  • …. proteins (synaptobrevin)

Bind to complementary …. on synaptic membrane

Assist in … vesicles and priming for …

A

SSV

  • v-SNARE proteins (synaptobrevin)

Bind to complementary t-SNARES on synaptic membrane

Assist in DOCKING vesicles and priming for RELEASE

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22
Q

SSV

  • Proteins comprising the … machine
  • … sensor (synaptotagmin)
A

SSV

  • Proteins comprising the EXOCYTOTIC machine
  • … sensor (synaptotagmin)
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23
Q

SSV

  • Proteins involved in endocytosis (…)
  • And formation of coated pits (…)
A

SSV

  • Proteins involved in endocytosis (DYNAMIN)
  • And formation of coated pits (CLATHRIN)
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24
Q

SSV docking

As noted earlier requires interaction … proteins

…. involved in vesicle trafficking throughout the cell

But specific v-SNARE and t-SNARE pairs mediate … … …

A

SSV docking

As noted earlier requires interaction SNARE proteins

SNARE involved in vesicle trafficking throughout the cell

But specific v-SNARE and t-SNARE pairs mediate mediate SYNAPTIC VESICLE DOCKING

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25
Q

SSV docking

v-SNARE = …

t- SNARE = … & …

A

SSV docking

v-SNARE = SYNAPTOBREVIN

t- SNARE = SYNATAXIN & SNAP25

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26
Q

Synaptic vesicle fusion with membrane promoted by …. “….”

L2&3, page 35-37

A

Synaptic vesicle fusion with membrane promoted by SNARE “ZIPPING”

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27
Q

Vesicle protein … provides a mechanism for Ca2+ regulation

A

Vesicle protein SYNAPTOTAGMIN provides a mechanism for Ca2+ regulation

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28
Q

L2&3, page 47

A

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29
Q

a-latrotoxin from the black widow spider interacts with a synaptic protein called …

Causes massive release of ….

but not …

A

a-latrotoxin from the black widow spider interacts with a synaptic protein called Neurexin

Causes massive release of SSV

but not LDCV

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30
Q

Objectives

  • What is a neurotransmitter?
  • How are neurotransmitters classified?
  • How are neurotransmitter receptors classified
  • How do neurotransmitters work?
A

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31
Q

Classification of Neurotransmitters

Type I: … ….

  • Glutamate (excitatory)
  • Glycine and GABA (inhibitory)

Type II: … & ….

  • Acetylcholine
  • Catecholamines (noradrenaline & dopamine)
  • ATP
  • Histamine

Type III: - ….
- Opioids, substance P, vasoactive intestinal peptide

Type IV: - ….
- NO, CO

A

Classification of Neurotransmitters

Type I: AMINO ACIDS

  • Glutamate (excitatory)
  • Glycine and GABA (inhibitory)

Type II: AMINES & PURINES

  • Acetylcholine
  • Catecholamines (noradrenaline & dopamine)
  • ATP
  • Histamine

Type III: - NEUROPEPTIDES
- Opioids, substance P, vasoactive intestinal peptide

Type IV: - GASES
- NO, CO

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32
Q

Criteria for a neurotransmitter

  • Present in the … terminal
  • The enzymes for its synthesis exist in the …. terminal or … ….
  • Released in response to nerve terminal ….
  • Specific receptors exist on the ….. membrane
  • Pharmacological agents should … or … neurotransmitter
A

Criteria for a neurotransmitter

  • Present in the PRESYNAPTIC terminal
  • The enzymes for its synthesis exist in the PRESYNAPTIC terminal or CELL BODY
  • Released in response to nerve terminal DEPOLARIZATION
  • Specific receptors exist on the POSTSYNAPTIC membrane
  • Pharmacological agents should MIMIC or
    INHIBIT neurotransmitter
33
Q

Fast acting receptors (milliseconds)

  • Have intrinsic .. … (ligand gated ion channels)
  • Channel opens to allow … or … of ions
  • … or … depending on ion involved and its direction of movement
A

Fast acting receptors (milliseconds)

  • Have intrinsic ION CHANNELS (ligand gated ion channels)
  • Channel opens to allow INFLUX or EFFLUX of ions
  • EXCITATORY or INHIBITORY depending on ion involved and its direction of movement
34
Q

Slow acting receptors (seconds)

  • …. …. (metabotropic) receptors
  • May have multiple actions (…. or …)
  • Directly regulate .. ….
  • Generate … …
  • Thus regulate enzyme activity and … …
A

Slow acting receptors (seconds)

  • G-PROTEIN COUPLED (metabotropic) receptors
  • May have multiple actions (EXCITATORY or INHIBITORY)
  • Directly regulate ION CHANNELS
  • Generate SECOND MESSENGERS
  • Thus regulate enzyme activity and GENE EXPRESSION
35
Q

Acetylcholine

  • ACh synthesized by … ….
  • Following synaptic release Ach degraded by ….
A

Acetylcholine

  • ACh synthesized by CHOLINE ACETYLTRANSFERASE
  • Following synaptic release Ach degraded by ACETYLCHOLINESTERASE
36
Q

Nicotinic receptors

  • Channel opens to allow … in (and … out)
  • Some subtypes allow … influx
A

Nicotinic receptors

  • Channel opens to allow Na+ in (and K+ out)
  • Some subtypes allow Ca2+ influx
37
Q

Muscarinic receptors

…. …. receptor

A

Muscarinic receptors

GPROTEIN COUPLED receptor

38
Q

GABA

  • An … … neurotransmitter
  • But … found in proteins
  • Synthesized only in … neurons by glutamic acid decarboxylase (…)
  • GAD therefore a good marker for …. neurone
  • Gaba neurons distributed widely in …
  • Following release GABA taken up by terminals or … …
A

GABA

  • An AMINO ACID neurotransmitter
  • But NOT found in proteins
  • Synthesized only in GABAnergic neurons by glutamic acid decarboxylase (GAD)
  • GAD therefore a good marker for GABAnergic neurone
  • Gaba neurons distributed widely in CNS
  • Following release GABA taken up by terminals or GLIAL CELLS
39
Q

GABA receptors

  • GABA action generally …
  • Involves both … (GABAa) and … (GABAb) receptors
  • GAbAa receptors are GABA-gated … channels
  • In some neurons Cl- may … and GABA is ….
A

GABA receptors

  • GABA action generally INHIBITORY
  • Involves both IONOTROPIC (GABAa) and METABOTROPIC (GABAb) receptors
  • GAbAa receptors are GABA-gated Cl- channels
  • In some neurons Cl- may EFFLUX and GABA is EXCITATORY
40
Q

GABAa receptors

  • …. increase opening frequency
  • …. increases opening duration
  • … also increases GABA action but depends on subunit structure of the receptor
  • These exogenous agents may be mimicking endogenous modulators such as …
A

GABAa receptors

  • BENSODIAZEPINES increase opening frequency
  • BARBITURATES increases opening duration
  • ETHANOL also increases GABA action but depends on subunit structure of the receptor
  • These exogenous agents may be mimicking endogenous modulators such as NEUROSTEROIDS
41
Q

GABAa receptors

  • Drugs that enhance GABA action are …
  • They reduce … (or panic)
  • Individuals with anxiety disorders may have … GABA activity
A

GABAa receptors

  • Drugs that enhance GABA action are ANXIOLYTIC
  • They reduce ANXIETY (or panic)
  • Individuals with anxiety disorders may have REDUCED GABA activity
42
Q

Catecholamines

  • Synthesised from …. by … …. (TH)
  • Produces …
  • In certain neurons synthesis continues to … & …
  • TH activity reduced by …. ….
  • TH activity increased by … influx resulting from enhanced stimulation
A

Catecholamines

  • Synthesised from TYROSINE by TYROSINE HYDROXYLASE (TH)
  • Produces L-DOPA
  • In certain neurons synthesis continues to NORADRENALINE & ADRENALINE
  • TH activity reduced by FEEDBACK INHIBITION
  • TH activity increased by Ca2+ influx resulting from enhanced stimulation
43
Q

Dopamine

Involved in …, …, attention and neuroendocrine

All mediated by … … receptors

Action terminated by reuptake by …. …. or …

Stimulants (cocaine and amphetamines) … reuptake, thus prolonging dopamine action

A

Dopamine

Involved in MOVEMENT, MOOD, attention and neuroendocrine

All mediated by G-PROTEIN COUPLED receptors

Action terminated by reuptake by NERVE TERMINAL or GLIA

Stimulants (cocaine and amphetamines) INHIBIT reuptake, thus prolonging dopamine action

44
Q

Dopamine

Dopaminergic neurons throughout ….

Facilitates initiation of …

Death of SN cells results in …. disease

Treat with ….

A

Dopamine

Dopaminergic neurons throughout CNS

Facilitates initiation of MOVEMENT

Death of SN cells results in PARKINSONS disease

Treat with L-DOPA

45
Q

Dopamine

  • L-dopa crosses into ..
  • Converted into …
  • But only in … neurons
  • Doesnt stop ….
A

Dopamine

  • L-dopa crosses into BRAIN
  • Converted into DOPAMINE
  • But only in SURVIVING neurons
  • Doesnt stop DEGENERATION
46
Q

VTA dopamine system also known as the …. system

  • A reward system which reinforces desirable …
  • … & … stimulate VTA dopamine neurones
  • … & …. increases DA at the synapse
  • … stimulation of reward pathway
A

VTA dopamine system also known as the MESOCORTICOLIMBIC system

  • A reward system which reinforces desirable BEHAVIOURS
  • OPIATES & NICOTINE stimulate VTA dopamine neurones
  • COCAINE & AMPHETAMINES increases DA at the synapse
  • INCREASES stimulation of reward pathway
47
Q

Prolonged activation of VTA results in ….

  • Generates … tolerance
  • Amphetamine addiction shows features of ….
A

Prolonged activation of VTA results in DOWN-REGULATION

  • Generates DRUG tolerance
  • Amphetamine addiction shows features of SCHIZOPHRENIA
48
Q

Dopamine and schizophrenia

Drugs effective against the “positive” symptoms of schizophrenia are called … or ….

Atypical antipsychotics block … … receptors

A

Dopamine and schizophrenia

Drugs effective against the “positive” symptoms of schizophrenia are called NEUROLEPTICS or ANTIPSYCHOTICS

Atypical antipsychotics block DOPAMINE D2 receptor

49
Q

ATP

  • Acts on … …
  • both … … and … …
A

ATP

  • Acts on PURINERGIC RECEPTORS
  • both ION CHANNELS and G-PROTEIN COUPLED
50
Q

Endocannabinoids

  • …. ligand for the cannabis receptor(s)
  • Synthesized in the ….. terminals in response to Ca2+ inflow
  • Acts as a … … to the presynaptic terminal
  • Activates … receptors which are coupled to G-proteins
A

Endocannabinoids

  • ENDOGENOUS ligand for the cannabis receptor(s)
  • Synthesized in the POST-SYNAPTIC terminals in response to Ca2+ inflow
  • Acts as a RETROGRADE SIGNAL to the presynaptic terminal
  • Activates CB1 receptors which are coupled to G-proteins
51
Q

Hypothalamus composed of 3 zones

…., ….. & …..

A

Hypothalamus composed of 3 zones

LATERAL, MEDIAL & PERIVENTRICULAR

52
Q

Periventricular has multiple functions including regulation of the …

A

Periventricular has multiple functions including regulation of the PITUITARY

53
Q

….. neurons project to posterior lobe of pituitary

Release … & ….

A

MAGNOCELLULAR neurons project to posterior lobe of pituitary

Release OXYTOCIN & ADH

54
Q

ADH regulates .. … …

Hypothalamus integrates multiple inputs relating to … … & …

ADH acts on … to increase … ….

ADH … blood vessels

A

ADH regulates EXTRACELLULAR FLUID VOLUME

Hypothalamus integrates multiple inputs relating to BLOOD PRESSURE & OSMOLALITY

ADH acts on KIDNEY to increase WATER RETENTION

ADH CONSTRICTS blood vessels

55
Q

Oxytocin involved in …. contraction and … …

A

Oxytocin involved in UTERINE contraction and MILK EJECTION

56
Q

The hypothalamus also controls the …. ….

  • ….. neurons
A

The hypothalamus also controls the ANTERIOR PITUITARY

  • PARVOCELLULAR neurons
57
Q

Parvocellular neurons secrete ….. hormones into the hypothalamic pituitary … ….

  • These signals travel to the .. ….
A

Parvocellular neurons secrete HYPOPHYSIOTROPIC hormones into the hypothalamic pituitary PORTAL CIRCULATION

  • These signals travel to the ANTERIOR PITUITARY
58
Q

Anterior pituitary releases

-
-
-
-
-
-
A

Anterior pituitary releases

  • Follicle stimulating hormone (FSH)
  • Luteinizing hormone (LH)
  • Thyroid stimulation hormone (TSH)
  • Adrenocorticotropic hormone (ACTH)
  • Growth hormone (GH)
  • Prolactin
59
Q

Steps of TRH:

  • L23, page 18
A

Steps of TRH:

60
Q

Steps of Prolactin

  • L23, page 21
A

svdg

61
Q

Steps of CRH

  • L23, page 26
A

sdxctfvgh

62
Q

Steps of GnRH

  • L23, page 30
A

defsrdg

63
Q

Estrogens are … and can enter the …

Estrogen receptors are widely distributed in the …

Concentrated in the .. & ….

A

Estrogens are LIPOPHILIC and can enter the BRAIN

Estrogen receptors are widely distributed in the CNS

Concentrated in the PITUITARY & HYPOTHALAMUS

64
Q

What do CNS estrogen receptors do?

Feedback signals to ….

Influence … & … activity

Initiate and support … …. brain structures

A

What do CNS estrogen receptors do?

Feedback signals to HYPOTHALAMUS

Influence SEXUAL & REPRODUCTIVE activity

Initiate and support SEXUAL DIMORPHIC brain structures

65
Q

What do CNS estrogen receptors do?

  • Increase the number of … …
A

What do CNS estrogen receptors do?

  • Increase the number of DENDRITIC SPINES
66
Q

Estrogens may influence neuronal activity via:

  • Classical … receptors to alter .. …
  • And … receptors to have …., … effects
  • These non-classical receptors may be located at or near the …
A

Estrogens may influence neuronal activity via:

  • Classical INTRACELLULAR receptors to alter GENE TRANSCRIPTION
  • And MEMBRANE receptors to have RAPID, NON-GENOMIC effects
  • These non-classical receptors may be located at or near the SYNAPSE
67
Q

Modulation of neurotransmission may provide a mechanism for …

referred to as … ….

Alterations must be … for the period of the memory

A

Modulation of neurotransmission may provide a mechanism for MEMORY

referred to as SYNAPTIC PLASTICITY

Alterations must be STABLE for the period of the memory

68
Q

Advantages in using simple organisms (invertebrates)

  • Small … …
  • Neurons themselves are …
  • Easy to identify … … and circuits
  • Small … & rapid … …
A

Advantages in using simple organisms (invertebrates)

  • Small NERVOUS SYSTEM
  • Neurons themselves are LARGE
  • Easy to identify INDIVIDUAL NEURONS and circuits
  • Small GENOME & rapid LIFE CYCLE
69
Q
  • Aplysia demonstrates a level of … & ….
  • Tactile stimulus to siphon causes .. …
  • Touch activates .. … in the siphon skin
  • Relayed to …. neuron (L7) in …. ganglion
  • Stimulates .. … and thus gill withdrawal
A
  • Aplysia demonstrates a level of LEARNING & MEMORY
  • Tactile stimulus to siphon causes GILL WITHDRAWAL
  • Touch activates SENSORY NEURONS in the siphon skin
  • Relayed to MOTOR neuron (L7) in ABDOMINAL ganglion
  • Stimulates GILL MUSCLES and thus gill withdrawal
70
Q
  • Repeated stimulus results in ….
  • represents … ….
  • Decreased ….. release from … neuron
  • Fewer …. released per action potential
A
  • Repeated stimulus results in HABITUATION
  • represents WEAKENED NEUROTRANSMITTER
  • Decreased NEUROTRANSMITTER release from SENSORY neuron
  • Fewer VESICLES released per action potential
71
Q

Aplysia can also demonstrate ….

  • Threatening stimuli result in …. sensitivity of the gill-withdrawal response
  • …. stimuli activate interneuron L29
  • This … neurotransmitter release from the … neuron presynaptic terminal
A

Aplysia can also demonstrate SENSITIZATION

  • Threatening stimuli result in INCREASED sensitivity of the gill-withdrawal response
  • NOXIOUS stimuli activate interneuron L29
  • This ENHANCES neurotransmitter release from the SENSORY neuron presynaptic terminal
72
Q

L29 releases …

  • Activates … receptors on presynaptic nerve terminal
  • Stimulates formation of …
  • Activates … … .. (PKA)
A

L29 releases 5HT

  • Activates 5HT receptors on presynaptic nerve terminal
  • Stimulates formation of cAMP
  • Activates PROTEIN KINASE A (PKA)
73
Q
  • PKA increases … on specific proteins
  • Phosphorylated K+ channels …
  • … does not exit terminal as rapidly
  • Voltage-sensitive … channels remain open
  • Greater Ca2+ influx … release of neurotransmitter
  • Stronger signal to .. …
  • Enhances … …
A
  • PKA increases PHOSPHORYLATION on specific proteins
  • Phosphorylated K+ channels CLOSE
  • K+ does not exit terminal as rapidly
  • Voltage-sensitive Ca2+ channels remain open
  • Greater Ca2+ influx INCREASES release of neurotransmitter
  • Stronger signal to MOTOR NEURON
  • Enhances GILL WITHDRAWAL
74
Q
  • Hippocampal input arrives from … …
  • Synapse onto neurons in the .. …
  • Axons from these neurons (mossy fibres) synapse onto … …
  • Axons from CA3 neurons …:
  • Out of hippocampus via …
  • And Schaffer collaterals to synapse onto …. neurons
A
  • Hippocampal input arrives from ENTORHINAL CORTEX
  • Synapse onto neurons in the DENTATE GYRUS
  • Axons from these neurons (mossy fibres) synapse onto CA3 CELLS
  • Axons from CA3 neurons BRANCH
  • Out of hippocampus via FORNIX
  • And Schaffer collaterals to synapse onto CA1 neurons
75
Q

What is the molecular mechanism responsible for LTP

The Schaffer collaterals release … on the … dendritic spines

AMPA channels open to allow … influx

NMDA channels open to allow … and … influx

But NMDA normally blocked by …

A

What is the molecular mechanism responsible for LTP

The Schaffer collaterals release GLUTAMATE on the CA1 dendritic spines

AMPA channels open to allow Na+ influx

NMDA channels open to allow Na+ and Ca2+ influx

But NMDA normally blocked by Mg2+

76
Q

At … levels of activity glutamate released

Activates … receptor

… influx promotes small … of dendritic spine

NMDA channels remain …

A

At LOW levels of activity glutamate released

Activates AMPA receptor

Na+ influx promotes small DEPOLARIZATION of dendritic spine

NMDA channels remain CLOSED

77
Q

At … levels of activity (tetanus) lots of glutamate released

Strong activation of … receptors

Large … influx promotes greater …. of dendritic spine

NMDA channels become ….

… and … enter dendritic spine

Calcium influx provides signal for … induction

A

At HIGH levels of activity (tetanus) lots of glutamate released

Strong activation of AMPA receptors

Large Na+ influx promotes greater DEPOLARIZATION of dendritic spine

NMDA channels become UNBLOCKED

Na+ and Ca+ enter dendritic spine

Calcium influx provides signal for LTP induction

78
Q

Presynaptic facilitation in aplysia is mediated by … … of K+ channels

A form of PKA can be generated that is active w/out …

Will therefore continue to phosphorylate the … channels after cAMP levels have declined

A

Presynaptic facilitation in aplysia is mediated by PKA PHOSPHORYLATION of K+ channels

A form of PKA can be generated that is active w/out cAMP

Will therefore continue to phosphorylate the K+ channels after cAMP levels have declined

79
Q

In LTP Ca2+ activates …

CaMKII phosphorylates …. receptors

CaMKI can also phosphorylate … (autophosphorylate)

Phosphorylated CaMKII is active w/out …

Thus continues to phosphorylate … receptors

A

In LTP Ca2+ activates CaMKII

CaMKII phosphorylates AMPA receptors

CaMKI can also phosphorylate ITSELF (autophosphorylate)

Phosphorylated CaMKII is active w/out CALCIUM

Thus continues to phosphorylate AMPA receptors

ANAT242 (6 decks)

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